The Moss Flora of Britain and Ireland

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The Moss Flora of Britain and Ireland This book describes and illustrates in detail the 763 species of mosses currently known to occur in the British Isles and incorporates the most up-to-date information available on classification and nomenclature, together with recent synonyms. The species descriptions provide information on frequency, ecology, geographical relationships and distribution, including information on protected species and those species at risk. For many species there are footnotes to aid identification. In addition to the species descriptions there are descriptions of families and genera and also introductory information on conservation, collection, preservation and examination of material, together with advice on using the keys. An artificial key to genera provides the only workable comprehensive key published in the English language. As a further aid to the user a list of English names for all British mosses is included, plus a comprehensive glossary and bibliography. This second edition incorporates the very considerable advances in knowledge of mosses made in the last quarter of the twentieth century. In this time eight species new to science have been described in Britain, 25 species not previously known in the British Isles have been discovered and taxonomic revisions have led to the addition of a further 51 species. Fourteen species have been removed, bringing the total number of species described to 763. Additionally, modern taxonomic methods have led to an increase in the number of genera from 175 to 214. This thoroughly updated and comprehensive Flora represents a unique resource for all those interested in this fascinating group of organisms TONY SMITH received undergraduate and postgraduate degrees from Lincoln College,

Oxford, before embarking on a research and teaching career at the University Colleges of Swansea and Bangor. He became Reader in Botany at the University of Wales, Bangor in 1981, retiring from this post in 1999. His book publications include Bryophyte Ecology, The Liverworts of Britain and Ireland and Atlas of the Bryophytes of Britain and Ireland (with M. O. Hill and C. D. Preston). He was editor of Journal of Bryology for 14 years and Secretary of the British Bryological Society’s distribution maps scheme for 30 years. He is currently an Honorary member of the British Bryological Society.

The Moss Flora of Britain and Ireland SECOND EDITION A. J. E. SMITH With illustrations by Ruth Smith Additional illustrations by A. J. E. Smith

CAMBRIDGE UNIVERSITY PRESS

Cambridge, New York, Melbourne, Madrid, Cape Town, Singapore, São Paulo Cambridge University Press The Edinburgh Building, Cambridge CB2 8RU, UK Published in the United States of America by Cambridge University Press, New York www.cambridge.org Information on this title: www.cambridge.org/9780521546720 © A. J. E. Smith 1978, 2004 This publication is in copyright. Subject to statutory exception and to the provision of relevant collective licensing agreements, no reproduction of any part may take place without the written permission of Cambridge University Press. First published in print format 2004 eBook (EBL) ISBN-13 978-0-511-33703-1 ISBN-10 0-511-33703-5 eBook (EBL) paperback ISBN-13 978-0-521-54672-0 paperback ISBN-10 0-521-54672-9

Cambridge University Press has no responsibility for the persistence or accuracy of urls for external or third-party internet websites referred to in this publication, and does not guarantee that any content on such websites is, or will remain, accurate or appropriate.

Dedicated to the memory of my beloved wife Ruth

Contents

Preface to the first edition Acknowledgements Preface to the second edition Second edition acknowledgements

page ix x xi xii

Introduction

1 1 2 2 3 4 4 4 5 5 7 7

Nomenclature Taxonomic categories Frequency and distribution Illustrations Literature cited Conservation Collection and preservation of material Examination of material Cutting sections Measurements Using the keys

Abbreviations

9

Conspectus of classification

10

Artificial key to the genera of British and Irish mosses

15

Division Bryophyta Class 1 Sphagnopsida Class 2 Andreaeopsida Class 3 Polytrichopsida Class 4 Bryopsida Diphysciideae Dicranideae Funariideae Bryideae

41 43 103 118 143 143 144 494 513

vii

viii

Contents

Geographical relationships of British and Irish mosses

936

Red List of Mosses

938

British and Irish vice-counties

941

English names for British and Irish mosses

945

Glossary Bibliography Index

965 983 986

Preface to the first edition

It is now more than fifty years ago that the third edition of The Student’s Handbook of British Mosses by H. N. Dixon & H. G. Jameson was published in 1924. Since that time the very considerable taxonomic and nomenclatural changes have been such that it is difficult for the non-expert to equate the 1924 taxa with those of today. Taxonomic revisions have resulted in the splitting of genera (and Dixon had an extraordinarily broad concept of the genus in The Handbook) and the recognition of numerous additional species especially in the Bryum capillare, B. erythrocarpum and Plagiothecium denticulatum/nemoreum complexes. As a consequence of the marked increase in interest in field bryology since the end of the Second World War numerous new species have been added to the British and Irish lists. Dixon recognised 115 genera and 625 species (in present day terms) compared with the 175 genera and 692 species described here. There is also an increasing awareness of the extent of morphological variation and the existence of taxonomically difficult groups requiring further study. It was felt that a new moss flora was long overdue, hence the production of this book. It must be stressed that this is not a revision of Dixon & Jameson but is a completely new moss flora embodying recent ideas and views, some doubtless controversial, on the taxonomy of mosses. Although I have sought opinions and guidance from many sources, except for the three genera contributed by other authors (Sphagnum, Campylopus and Pottia) the views expressed here are entirely my own. Bangor, August 1976

ix

Acknowledgements

I am greatly indebted to Mr A. C. Crundwell for the assistance afforded me during the preparation of this flora. He has been unstinting in his help over nomenclature, in taxonomic discussion and the loan of specimens. I have made free use of his manuscripts on certain genera of the Dicranaceae, Mnium and accounts of species not previously described from Britain. Without his assistance the preparation of the book would have been a much more onerous task. I have received much comment and helpful criticism from Dr E. V. Watson, Professor P. W. Richards allowed me free access to his herbarium; to both these bryologists I am most grateful. I wish also to tender my thanks to the following individuals for the loan of specimens or the provision of information: Mrs J. Appleyard, Mr M. F. V. Corley, Mr L. Derrick, Dr U. K. Duncan, Dr J. G. Duckett, Mr Alan Eddy, Mr M. O. Hill, Mrs J. A. Paton, Mr A. R. Perry, Dr F. Rose, Mr E. C. Wallace and Dr H. L. K. Whitehouse. The Directors or Curators of the following institutions have also been most helpful in lending material: British Museum (Natural History); Royal Botanic Garden, Edinburgh; National Museum of Wales, Cardiff; National Botanic Gardens, Dublin; the Manchester Museum, University of Manchester; Department of Botany, University of Oxford; Botanical Museum, University of Helsinki; Museum of Natural History, Stockholm; and the New York Botanical Gardens. I am indebted to Professor J. L. Harper of the School of Plant Biology, University College of North Wales for providing facilities and for his forbearance during the progress of this work. Finally I would like to thank my wife for all the time and trouble spent in preparing illustrations and my mother who typed much of the manuscript, often from almost illegible handwriting.

x

Preface to the second edition

Since the publication of the first edition in 1978, in which 693 species were described, there have been considerable advances in our knowledge of British and Irish mosses and in the taxonomy of critical groups such as Andreaea and the Hypnum cupressiforme, Racomitrium heterostichum, R. canescens and Schistidium apocarpum complexes. Since 1978, eight species new to science have been described in Britain, 25 species not previously known in the British Isles have been discovered and taxonomic revisions have led to the addition of a further 51 species. Fourteen species have been reduced to varieties of or to synonymy with other species or removed from the British list. This has resulted in an increase of 70 in the number of species making a total of 763. Additionally, critical studies of generic limits, as in the Amblystegiaceae and Pottiaceae, and DNA studies have led to a considerable increase in the number of genera – from 175 to 214 in the British Isles. There have also been major changes in the overall classification of mosses. Clearly, the first edition of this book was in dire need of updating. Apart from additions and taxonomic changes, the original descriptions of species have been revised and in some instances augmented and footnotes added or increased where thought necessary. The key to genera and keys to species have been revised in the light of experience since they were first published. Llandudno, Conwy, March 2003

xi

Second edition acknowledgements

To those whose help was acknowledged in the first edition I would like to add the following: Mrs Kathryn Childerhouse, National Museums and Galleries of Wales, ´ Munoz, ˜ ´ for the loan of specimens, Dr Jesus Real Jard´ın Botanico, Madrid, for assistance with Grimmia and Dr Rosa Ma Ros for providing photographs of Pottia spores. I am also most grateful to Mr T. L. Blockeel, Mr A. C. Crundwell, Dr S. R. Edwards, Dr M. O. Hill, Dr D. T. Holyoak, Mr G. P. Rothero, Mr C. C. Townsend and Dr H. L. K. Whitehouse for the provision of material and/or information. I would also like to thank the many correspondents who over the years have made suggestions and pointed out improvements that could be made to the first edition of this book. I am indebted to Dr S. R. Edwards for providing the cover photographs and Figure 1 and information on section cutting. I would particularly like to thank Mr Roy Perry for his unstinting help and for undertaking the arduous task of proof-reading the original typescript. And finally, also much appreciated, was the care taken by Alison Litherland of Cambridge University Press in copyediting the manuscript.

xii

Introduction

For information on all aspects of bryology see A. J. Shaw & B. Goffinet (eds.), Bryophyte Biology, Cambridge University Press, 2000.

Nomenclature I have followed the nomenclature of Corley et al. (1981) deviating from this where there have been subsequent taxonomic or nomenclatural changes. Only recent synonyms are given except for names used by Dixon & Jameson (1924). Author abbreviations are those recommended by Brummitt & Powell (1992) although where three or more authors are involved I have used only the first name followed by et al. (e.g. Gaertn. et al. rather than Gaertn., B. Mey. & Scherb.). Authorities for species are those given on the Missouri Botanic Garden website W3 MOST (http://mobot.mobot.org/W3T/Search/most.html). For place of publication abbreviations I have followed Crosby (1999).

Bryologia Europaea citations Bryologia Europaea was published in 65 fascicles between 1837 and 1855 but not in any systematic order. On the title pages the names P. Bruch, W. P. Schimper ¨ ¨ and W. T. Gumbel appear. However, the general consensus now is that Gumbel was the illustrator and did not describe any mosses and I have therefore not used his name for any Bryologia Europaea citations. The citation of Bruch & Schimper or Schimper alone is also problematic. Bruch died in 1847 and the last part of Bryologia Europaea did not appear until 1855. I have followed Stafleu & Cowan (1976) who give the date and authorship of each genus in Bryologia Europaea. The frequently used citation BSG should be avoided.

Use of ex and in ‘Ex’ is used to connect the names of two or more persons, for example Schimp. ex ¨ Hal., the second of whom (C. Muller, ¨ Mull. Halle) validly published a name proposed by but not validly published by the first person (Schimper). When citing authorities, for example on a moss packet, both names or groups of names should be used. 1

2

Introduction

‘In’ is used to connect the names of two persons (e.g. Hook. in Grev.) the second of whom (Greville) was the editor or author of a work in which the first person (Hooker) was responsible for validly publishing or making available a name. When citing the authority for a moss name it is not necessary to cite the ‘in’ name. The ‘in’ author is only used when the publication is cited.

English names of mosses I have not given English names of mosses in the text as they are more difficult to remember and often more cumbersome than Latin names. However, there is the absurd requirement in the Wildlife and Countryside Act, 1981, for common names to be used. I have therefore provided a list of preferred English names (pp. 945–964) from Edwards (1999).

Taxonomic categories In the first edition of this book I adopted a somewhat broader concept of the genus than some other authors of the time but it is now clear that as a result of genetical and other studies this was incorrect, hence the increase in the number of genera from 175 to 214. More equivocal is the status of a number of taxa now recognised as species but treated in the past as varieties or subspecies. However, I have followed, albeit sometimes somewhat reluctantly, current practices in the treatment of such taxa.

Frequency and distribution The publication of volumes 2 and 3 of the Atlas of the Bryophytes of Britain and Ireland (Hill et al. 1992, 1994) has provided a much better picture of the frequency and distribution of mosses than was available at the time the first edition of this Flora was written and it has proved possible to give more accurate information on a regional basis. I have used six estimates of frequency : very rare, rare, occasional, frequent, common and very common. To which of these categories a particular species belongs is to some extent a matter of personal opinion but it was felt that this system was more satisfactory than using a multiplicity of phrases such as ‘not infrequent’, ‘not uncommon’ etc. that have been used elsewhere. There are two sets of frequency figures given at the end of the British and Irish distribution information. The first is the number of vice-county records in Britain and Ireland. There are 112 British and 40 Irish vice-counties and one for the Channel islands. As an example, 17, H3, C means the plant has been recorded from 17 British, 3 Irish vice-counties and the Channel Islands. The second set of figures is the number of 10 km squares of the British Ordnance Survey National Grid and Irish Ordnance Survey/Suirbheireacht Ordonais National Grid from which species have been recorded. The Universal Transverse

Illustrations

3

Mercator (UTM) grid is used for the Channel Islands. There are about 2640 British 10 km squares, about 1000 Irish and 15 Channel Islands’. Records from 1950 onwards and those pre-1950, indicated by *, are distinguished. Thus, GB873 + 98*, IR86 + 7*, C6 + 2* indicates 73 recent and 98 pre-1950 records from Great Britain, 86 recent and 7 pre-1950 Irish records and 6 recent and 1 pre-1950 Channel Islands’ records. These figures have been taken from Hill et al. (1992, 1994). The figures for Great Britain and the Channel Islands are a reasonable indication of frequency and whether or not species have decreased. The Irish records are incomplete because of inadequate recent recording in Ireland and many old records are the only ones available and should not be taken as an indication of change in frequency. Altitudinal ranges have also been taken from Hill et al. (1992, 1994). Hill & Preston (1998) carried out an analysis of the geographical relationships of the bryophytes of the British Isles and they recognized 43 floristic elements. The element to which each species belongs is given in italics in the distribution data in this Flora. For further information on this see pp. 936–937. Information on world distribution comes from Duell (1984, 1985, 1992), supplemented with data from other sources where appropriate. Most distributional information predates recently changed political boundaries; hence the use of Czechoslovakia and Yugoslavia. The term Macaronesia technically covers the extreme S. W. corner of the Iberian Peninsula, Madeira, the Azores, Canary Islands, Salvage Islands, Cape Verde islands and the coastal strip of N. W. Africa. The sense in which I use the term includes what is referred to in German as LauriMakaronesien, i.e. the Azores, Madeira and the Canary Islands.

Illustrations With the exception of a small number of species (Buxbaumia viridis, Cinclidotus riparius, Cynodontium gracilescens, Grimmia crinita, G. elatior, Lescuraea saxicola, Meesia triquetra, Mnium medium, Neckera pennata, Orthotrichum gymnostomum, O. shawii, Paraleucobryum longifolium, Schistidium flaccidum, Syntrichia norvegica, Tetrodontium repandum, Trematodon ambiguus, Weissia controversa var. wimmeriana) all figures have been prepared from British and Irish specimens, although some have been augmented by material from other sources, as far as possible from continental Europe. Illustrations from the first edition, except for those of Tortula species 12–16, Protobryum bryoides, Pottia and Microbryum rectum, which were drawn by Miss Gillian A. Meadows of the Royal Botanic Garden, Edinburgh, were prepared by Mrs Ruth Smith using a Leitz Laborlux microscope with either a Leitz camera lucida or a Leitz drawing apparatus. Additional drawings for this edition were made by the author using the same equipment. Figure 1 was drawn by Dr S. R. Edwards and the photographs in Fig. 115 were provided by Dr Rosa Ma Ros of the Universidad de Murcia. For reasons of economy only the minimum of illustrations has been used and habit drawings have for the most part been omitted, being of little use.

4

Introduction

They need be of such a size that they take up an amount of space far in excess of their value.

Literature cited Where a reference is not listed in the Bibliography it is given in full in the text, e.g. A. C. Crundwell, Trans. Brit. Bryol. Soc. 4, 67–74, 1965. Where a work is listed in the Bibliography, only name(s) of author(s) and date of publication are cited in the text, e.g. Dixon & Jameson (1924).

Conservation A number of bryophytes have decreased markedly over the past 100 years and many species are now endangered or at risk. The reasons for this are varied – urbanisation, industrialisation, changing agricultural practices, atmospheric and aquatic pollution and over-collection (see A. J. E. Smith, Mosses, liverworts and hornworts in D. L. Hawkesworth, ed., The Changing Wildlife of Great Britain and Ireland, 2000, for the situation since 1973). Care should therefore be taken when collecting bryophytes. If material is sparse only the minimum amount necessary for determination should be collected. This applies particularly to cushion or tuft forming species, some of which, such as Grimmia species, are very slow growing. DO NOT REMOVE A WHOLE SPECIMEN IF IT IS THE ONLY ONE GROWING AT A PARTICULAR SITE. A photograph is a very satisfactory alternative as it preserves the original habit and colour of the plant concerned and can also illustrate features of the habitat. For useful information on the photography of bryophytes see S. R. Edwards, J. Bryol. 16, 443–84, 1991. The Joint Nature Conservation Council has produced a Red List of British Mosses (Church et al., 2001), giving extinct, critically endangered, endangered and vulnerable species. This list is given on pp. 936–938 and I have indicated in the list those species that it is a criminal offence under the Wildlife and Countryside Act, 1981 to collect. However, this 1981 list of mosses is unsatisfactory as it seems to be a random selection of rare species made without reference to competent field bryologists. Also, some of the species listed cannot be identified without collecting a specimen, hence the strictures on care in collecting. Recently, a database of threatened bryophytes was set up (see N. G. Hodgetts, Bull. Br. Bryol. Soc. 80, 52–9, 2003).

Collection and preservation of material An adequate specimen for determination should be collected, bearing in mind the above comments on conservation, which will show part or whole of the growth form of the moss. A search should be made for perichaetia and perigonia and sporophytes as these may be useful or essential for identification. For mosses

Cutting sections

5

growing in temporary or unstable habitats it is useful to collect 5 mm or so of the substrate beneath the plant so that rhizoidal gemmae if present are collected. If specimens cannot be examined immediately they should be air dried as plants left in wet paper packets, polythene bags or dishes of water often grow etiolated shoots and may become mouldy. Specimens are best put in appropriately labelled newspaper or paper packets (not envelopes which undo if wet). They should not be pressed as pressed mosses often do not recover their original shape when remoistened. Once dried, mosses can be kept indefinitely. Specimens even a hundred or more years old will assume their original form when moistened, although they may have lost their original coloration. Bryophytes are best kept in flat paper packets on which collection data and any other relevant information (name, habitat, altitude, locality, grid reference, collector, collection number, date) can be written. Packets may conveniently be made from A4 sheets of non-acid paper. The bottom one-third of the sheet is folded upwards, the two sides folded inwards thus forming a pocket to contain the specimen. The top third is then folded over and information can be written on the upper side.

Examination of material Specimens or portions of specimens should be moistened before dissection as dry mosses are often brittle. Where difficulty is experienced with remoistening dried plants, as with members of the Fissidentaceae, Mniaceae and Polytrichaceae, the process can be expedited by adding a little household detergent to the water used. Dissection of specimens is best carried out using a dissecting microscope as most mosses are too small to do this satisfactorily with the naked eye. For study of leaf shape, cells, etc. leaves should be removed from stems, care being taken that complete leaves are detached as basal and alar cells are often important in identification. It should be remembered that auricles if present, as in Plagiomnium and Plagiothecium, may remain attached to the stem, so it is useful to mount a piece of stem, from which leaves have been stripped, on a slide to check this.

Cutting sections The following method, modified from an account by Dr S. R. Edwards (pers. commun.), allows good transverse sections of about 10 μm thickness to be taken from any required part of a moss leaf or stem. If possible, a dissecting microscope should be used. For leaf sections selected, moist leaves should be arranged parallel to each other on a glass slide, with the parts to be sectioned aligned as arrowed in Fig. 1(a). A second slide is laid over the leaves, so that its long edge is also aligned with the parts to be sectioned (Fig. 1(b)). Firm pressure is applied to the upper slide by the

6

Introduction

Fig. 1 Diagram illustrating technique for section cutting. (a) arrangement of leaves on lower slide; (b) cutting sections; (c) angle of tilt, θ, of razor blade. P1 and P2 are fulcrums.

finger of one hand (Fig. 1(b)), and half a double-edged razor blade is drawn with the other hand across the leaves, using the upper slide as a guide (Fig. 1(b)). Only a corner of the blade is used, with an angle of elevation of the blade of about 15◦ –20◦ . This should give a perfectly clean cut. Sections are made by adjusting the angle of tilt of the razor blade for each successive cut. The first cut is made with the blade at an angle of about 15◦ –20◦ from the vertical. This angle is progressively reduced with each successive cut. This is shown diagrammatically in Fig. 1(c), where θ is the angle of tilt and P1 is the fulcrum. Depending upon the change in the angle of tilt with successive cuts, so the thickness of sections can be controlled. After the tilt of the blade has passed 0◦ (vertical), the fulcrum moves down to P2 (Fig. 1(c)), resulting in a finer control over the thickness of the last few sections. Pressure on the blade has to be judged by experience, but it should be no more than is necessary to cut the leaves. One blade corner may provide many series of sections and only with very

Using the keys

7

old and fragile material should a fresh corner be used for each operation. With a little practice excellent sections can be cut. For small leaves and sections of stems or branches, as in Sphagnum, the same technique is used. But stems or branches are laid side by side.

Measurements Height of plants is height of the gametophyte and excludes any sporophytes that may be present. Leaf length is from middle of insertion to apex unless otherwise stated (in some mosses with hyaline leaf apices). Cell dimensions are from middle lamella (or where it would be if visible) to middle lamella. Capsule length is from mouth to junction between neck and seta.

Using the keys It is important that with each dichotomy of a key both parts are read carefully and particular note taken where ‘usually’ and ‘or if’ occur. Once a plant has been named it is essential that the specimen is carefully compared with the specific description and illustration before any firm conclusion is reached as to its identity.

Key to genera It must be stressed that the generic key is merely a guide to the allocation of specimens to genera and is far from infallible. Unfortunately, many characters that are useful in classification, such as peristome structure, sex and DNA sequences, may not be available in material collected or may only be useable with highly sophisticated technical equipment. Also, differences in appearance that enable an expert to determine a moss in the field with a hand lens cannot be described in quantitative or qualitative terms and it is necessary to rely on characteristics such as excurrence of costae or degree of papillosity that are open to misinterpretation or ambiguity. Whilst every effort has been made to avoid the use of vague or relative characters, because of the poor distinctions between some genera, such as some members of the Brachytheciaceae or Pottiaceae, precise definition is impossible. Where generic distinctions are based on the sporophyte, as in the Funariaceae, it may not be possible to identify sterile material. Where a species may exhibit both alternatives of a dichotomy, e.g. excurrence/non-excurrence of the costa or margins plane/recurved, allowance has been made as far as possible in the keys. However, allowing for every eventuality would make the key inordinately long and when in doubt it may be necessary to try both alternatives of a dichotomy. In acrocarpous mosses leaf characters are based upon leaves from the upper part of the stem or comal leaves but care should be taken that perichaetial or perigonial

8

Introduction

leaves are not used as these may differ in shape and areolation from stem leaves. In pleurocarpous mosses stem and branch leaves may be very different in form, especially in the Brachytheciaceae, and leaf characters refer to stem leaves unless otherwise stated. Where there is an overlap in dimensions such as cell size, only with very few exceptions are specimens encountered with the dimensions exactly in the overlap range. Thus if cells in one taxon are given as 8–16 μm and in a second as 14– 24 μm the majority of cells in the first will be less than 14 μm long and those in the second mostly more than 16 μm long.

Keys to species The same remarks apply to the keys to species, although in most instances the characters are more clear cut and misinterpretation less likely. However, difficulty may be experienced with genera such as Bryum, Didymodon and some Brachytheciaceae. It must be remembered that this is a regional flora and that some of the key dichotomies will not necessarily work elsewhere. Thus in the generic key in dichotomy 86, Coscinodon is separated from Grimmia and Schistidium by having plicate leaves, but in Continental Europe Coscinodon humilis Milde lacks leaf plicae and Grimmia caespiticia (Brid.) Jur. has strongly plicate leaves.

Abbreviations

auct. C c. cm GB H IR KOH m m n q.v. s.s. ssp. var. x μm ± ∗ ∗

Auctor(es), author(s) Channel Islands (referring to the vice-county or the number of 10 km grid squares in the Channel Islands) circa, approximately centimetre Great Britain (referring to the number of 10 km grid squares in Great Britain) Hibernia, Ireland (referring to number of vice-counties in Ireland) Ireland (referring to the number of 10 km grid squares in Ireland) Potassium hydroxide (2% solution) metre m-chromosomes, micro-chromosomes the functional haploid chromosome number quod vide, which see sensu stricto, in the strict sense subspecies variety basic haploid chromosome number micron, 1 × 10−6 m, 1 /1000 mm; colloquially ‘mu’ more or less following a chromosome number, means based on British or Irish material following number of grid squares, meaning pre-1950 records

9

Conspectus of classification

Traditionally, the division Bryophyta has included three classes, Hepaticopsida or Marchantiopsida (liverworts), Anthocerotopsida (hornworts) and Musci (mosses). Recent evidence, however, suggests that at an early stage in the evolution of terrestrial plants the liverworts diverged from other land plants, then hornworts diverged and finally mosses (see Willis & McElwain, 2002). Thus, the original concept of the division Bryophyta as consisting of three classes cannot be maintained and it is here considered to consist only of the mosses. Until the beginning of the 1980s the classification of mosses was based upon the morphology and anatomy of the gametophyte and sporophyte and it was sometimes a matter of dispute as to which of the two should be used for a particular group. Over the past 20 years or so new techniques have been developed, especially DNA sequencing, which provide information on the genetic relationships of taxa. This has confirmed some older classifications but others have been shown to be incorrect. The classification of mosses is now in a state of flux as a result of the development of these new techniques, Rather than using a traditional classification, such as that used by Corley et al. (1981), which is clearly very out of date, I have followed the tentative classification of D. H. Vitt (in Shaw & Goffnet, 2000). However, it is likely that further studies will lead to refinements, and even major changes, to this classification.

Division Bryophyta (Musci) Class 1. Sphagnopsida Order 1. Sphagnales Family 1. Sphagnaceae 1. Sphagnum

Class 2. Andreaeopsida Order 2. Andreaeales Family 2. Andreaeaceae 2. Andreaea

Class 3. Polytrichopsida Order 3. Polytrichales Family 3. Polytrichaceae

3. 4. 5. 6. 7. Order 4. Family 4. 8. 9. Family 5. 10.

10

Pogonatum Polytrichastrum Polytrichum Oligotrichum Atrichum Tetraphidales Tetraphidaceae Tetraphis Tetrodontium Oedipodiaceae Oedipodium

Conspectus of classification Order 5. Buxbaumiales Family 6. Buxbaumiaceae 11. Buxbaumia

Class 4. Bryopsida Subclass 1. Order 6. Family 7. 12. Subclass 2. Order 7. Family 8. 13. Order 8. Family 9. 14. 15. 16. 17. 18. 19. 20. 21. Family 10. 22. Family 11. 23. 24. 25. 26. 27. 28. Family 12. 29. 30. 31. 32. 33. 34. 35. 36. Family 13. 37. Family 14.

Diphysciideae Diphysciales Diphysciaceae Diphyscium Dicranideae Archidiales Archidiaceae Archidium Dicranales Ditrichaceae Pleuridium Pseudephemerum Trichodon Ditrichum Saelania Distichium Ceratodon Cheilothela Bruchiaceae Trematodon Rhabdoweisiaceae Rhabdoweisia Oreoweisia Cynodontium Oncophorus Dichodontium Dicranoweisia Dicranaceae Aongstroemia Dicranella Arctoa Kiaeria Dicranum Dicranodontium Campylopus Paraleucobryum Leucobryaceae Leucobryum Fissidentaceae

38. 39. Family 15. 40. Order 9. Family 16. 41. 42. 43. 44. 45. 46. 47. 48. 49. 50. 51. 52. 53. 54. 55. 56. 57. 58. 59. 60. 61. 62. 63. 64. 65. 66. 67. 68. 69. 70. 71. 72. Family 17. 73. Family 18. 74. 75.

Fissidens Octodiceras Schistostegaceae Schistostega Pottiales Pottiaceae Eucladium Weissia Tortella Trichostomum Pottiopsis Pleurochaete Paraleptodontium Dialytrichia Pseudocrossidium Bryoerythrophyllum Leptodontium Hymenostylium Anoectangium Gyroweisia Gymnostomum Molendoa Barbula Didymodon Scopelophila Stegonia Pterygoneurum Aloina Leptobarbula Tortula Protobryum Phascum Pottia Microbryum Hennediella Acaulon Leptophascum Syntrichia Cinclidotaceae Cinclidotus Ephemeraceae Micromitrium Ephemerum

11

12 Order 10. Family 19. 76. 77. 78. 79. Family 20. 80. 81. 82. Order 11. Family 21. 83. 84. 85. Subclass 3. Order 12. Family 22. 86. Order 13. Family 23. 87. Order 14. Family 24. 88. Family 25. 89. 90. 91. 92. Subclass 4. Order 15. Family 26. 93. 94. 95. 96. Family 27. 97. 98. 99. 100.

Conspectus of classification Grimmiales Grimmiaceae Coscinodon Schistidium Grimmia Racomitrium Ptychomitriaceae Ptychomitrium Glyphomitrium Campylostelium Seligeriales Seligeriaceae Blindia Seligeria Brachydontium Funariideae Timmiales Timmiaceae Timmia Encalyptales Encalyptaceae Encalypta Funariales Disceliaceae Discelium Funariaceae Funaria Entosthodon Physcomitrium Aphanorrhegma Bryideae Splachnales Splachnaceae Tayloria Tetraplodon Aplodon Splachnum Meesiaceae Paludella Meesia Amblyodon Leptobryum

Family 28. 101. Order 16. Family 29. 102. Family 30. 103. 104. 105. 106. Family 31. 107. 108. 109. 110. 111. 112. 113. 114. Family 32. 115. Family 33. 116. 117. 118. 119. 120. Order 17. Family 34. 121. Family 35. 122. 123. 124. Order 18. Family 36. 125. Order 19. Family 37. 126. Family 38. 127.

Catoscopiaceae Catoscopium Bryales Orthodontaceae Orthodontium Bryaceae Plagiobryum Anomobryum Bryum Rhodobryum Mniaceae Mielichhoferia Epipterygium Pohlia Mnium Cinclidium Rhizomnium Plagiomnium Pseudobryum Aulacomniaceae Aulacomnium Bartramiaceae Plagiopus Bartramia Conostomum Philonotis Breutelia Orthotrichales Amphidiaceae Amphidium Orthotrichaceae Zygodon Orthotrichum Ulota Hedwigiales Hedwigiaceae Hedwigia Rhizogoniales Rhizogoniaceae Leptotheca Calomniaceae Calomnion

Conspectus of classification Order 20. Family 39. 128. 129. Family 40. 130. Family 41. 131. 132. Order 21. Family 42. 133. Family 43. 134. Family 44. 135. 136. Family 45. 137. 138. 139. Family 46. 140. Family 47. 141. Family 48. 142. 143. Family 49. 144. Family 50. 145. 146. 147. Family 51. 148. Family 52. 149. 150. 151. 152. 153.

Hookeriales Hookeriaceae Hookeria Achrophyllum Pilotrichaceae Cyclodictyon Daltoniaceae Calyptrochaeta Daltonia Hypnales Fontinalaceae Fontinalis Climaciaceae Climacium Cryphaeaceae Cryphaea Dendrocryphaea Leucodontaceae Leucodon Antitrichia Pterogonium Myuriaceae Myurium Leptodontaceae Leptodon Neckeraceae Neckera Homalia Thamnobryaceae Thamnobryum Pterigynandraceae Pterigynandrum Habrodon Heterocladium Myriniaceae Myrinia Leskeaceae Leskea Pseudoleskeella Pseudoleskea Lescuraea Ptychodium

Family 53. 154. Family 54. 155. 156. Family 55. 157. 158. Family 56. 159. 160. 161. 162. Family 57. 163. 164. 165. 166. 167. 168. 169. 170. 171. 172. 173. 174. 175. 176. Family 58. 177. 178. 179. 180. 181. 182. 183. 184. 185. 186. 187. 188. 189.

Anomodontaceae Anomodon Thuidiaceae Abietinella Thuidium Helodiaceae Helodium Palustriella Amblystegiaceae Cratoneuron Amblystegium Hygroamblystegium Leptodictyum Campyliaceae Conardia Campylium Campyliadelphus Drepanocladus Warnstorfia Straminergon Calliergon Scorpidium Hamatocaulis Tomentypnum Pseudocalliergon Sanionia Hygrohypnum Pictus Brachytheciaceae Isothecium Scorpiurium Homalothecium Brachythecium Pseudoscleropodium Scleropodium Cirriphyllum Platyhypnidium Rhynchostegium Eurhynchium Kindbergia Oxyrrhynchium Rhynchostegiella

13

14 Family 59. 190. Family 60. 191. 192. 193. 194. 195. 196. 197. 198. Family 61. 199. Family 62. 200.

Conspectus of classification Entodontaceae Entodon Plagiotheciaceae Myurella Platydictya Orthothecium Plagiothecium Isopterygiopsis Pseudotaxiphyllum Herzogiella Taxiphyllum Sematophyllaceae Sematophyllum Hypnaceae Campylophyllum

201. 202. 203. 204. 205. 206. 207. 208. Family 63. 209. 210. 211. 212. 213. 214.

Calliergonella Pylaisia Platygyrium Homomallium Hypnum Ptilium Ctenidium Hyocomium Hylocomiaceae Rhytidium Pleurozium Rhytidiadelphus Loeskeobryum Hylocomiastrum Hylocomium

Artificial key to the genera of British and Irish mosses For information on use of this key see pages 7–8 1 Plants acrocarpous Plants pleurocarpous

2 192

Note. Acrocarpous mosses are those in which the main axis of the gametophyte is sympodial and is usually ± erect. The plants usually form turfs or cushions or may occur as scattered or gregarious individuals. Leaf cells are isodiametric to narrowly rectangular, narrowly hexagonal or rarely linear; the costa may be excurrent. Gametangia and sporophytes are produced at the apices of stems or main branches with further vegetative growth continued by lateral branch(es) or innovation(s). Pleurocarpous mosses have monopodial main stems. These are usually prostrate to ascending, producing secondary stems or branches and the plants often form mats or wefts or occur as scattered ± prostrate shoots. Stem leaves may be of different size and shape from branch leaves, leaf cells are often ± linear and the costae are very rarely excurrent. Gametangia are produced on dwarf bud-like lateral branches on the main stems and branches and because of this sporophytes may appear to grow directly from these. In a few instances (e.g. Cryphaea, Fontinalis) pleurocarpous mosses are cladocarpous with gametangia borne on short lateral branches. 2 Branch leaves ecostate, with network of green cells surrounding large hyaline cells with annular thickenings, branches in fascicles 1. Sphagnum (p. 44) Leaves costate or rarely ecostate, green cells not forming network, large hyaline cells lacking, branches not in fascicles 3 3 Plants saxicolous, deep red to brown or blackish, fragile when dry, leaf cell walls strongly incrassate, reddish to brownish, capsules dehiscing by 4(−8) longitudinal slits 2. Andreaea (p. 103) Habitat various, plants not as above, capsules dehiscing by a lid or cleistocarpous 4 4 Gametophytes minute, leaf and perichaetial leaf margins ciliate, setae coarsely papillose, capsules inclined, oblique, somewhat flattened on upper side 11. Buxbaumia (p. 141) Plants not as above 5 15

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5 Leaf cells 2–3-stratose, obscure, costa poorly defined, perichaetial bracts with ciliate margins, capsules immersed, oblique 12. Diphyscium (p. 143) Plants not as above 6 6 Basal cells of leaves linear, transverse walls thin, longitudinal walls thick, sinuose-nodulose, cells above with sinuose walls, peristome teeth divided into filiform segments 79. Racomitrium (p. 457) Leaf areolation not as above, peristome teeth if present divided or not 7 7 Leaves lingulate to spathulate, rarely oblong-lanceolate, basal cells large, hyaline, narrower at the margins, cells above strongly papillose, very obscure, calyptrae completely covering erect cylindrical capsules, axillary uniseriate branched propagules to 2 mm long sometimes present 87. Encalypta (p. 497) Plants not as above 8 8 Plants occurring on dung or decaying animal remains 28 Substrate various but not dung or decaying animal remains, capsules without conspicuous hypophysis (except in Trematodon) 9 9 Capsules cleistocarpous 30 Capsules dehiscent or absent 10 10 Leaves distichous or complanate 41 Leaves spirally arranged 11 11 Plants with axillary bulbils or with gemma-cups or gemma-bearing pseudopodia at shoot tips 46 Plants without bulbils, gemma-cups or pseudopodia 12 12 Leaves ecostate 49 Leaves costate 13 13 Capsules ± globose or subglobose when moist, plants not ephemeral or if so then setae cygneous 187 Capsule shape various but not globose or subglobose or if so then plants ephemeral and setae straight, or capsules absent 14 14 Leaves with filaments or lamellae on adaxial side of costa at least in upper part of leaf 51 Leaves lacking lamellae or filaments on adaxial side 15 15 Leaves squarrose or squarrose-recurved when moist 55 Leaves appressed or imbricate to reflexed but not squarrose when moist 16 16 Leaf margins with border of narrow cells or with several-stratose marginal band 61 Leaves unbordered, without thickened marginal band 17 17 Plants minute, to 2(−3) mm high or if more then leaves markedly trifarious, saxicolous, forming lax or rarely dense patches, sporophytes usually present (except in Leptobarbula) 73 Plants very small to large, leaves not trifarious, habitat and habit various, sporophytes present or not 18

Artificial key to the genera

17

18 Plants terricolous, ephemeral or short-lived, scattered or gregarious, sporophytes usually present 76 Plants persisting, habit and habitat various, sporophytes present or not 19 19 Costa excurrent in hyaline hair-point or leaf apices hyaline when moist, whitish when dry 83 Costa if excurrent not forming hyaline hair-point, leaf apices not hyaline 20 20 Leaf apices obtuse or rounded 88 Leaves subacute to longly acuminate 21 21 Mid-leaf cells ± isodiametric 22 Mid-leaf cells longer than wide 25 22 Basal cells of leaves hyaline, ascending up margins, transition from basal to upper cells usually abrupt, V-shaped 43. Tortella (p. 278) Basal cells if hyaline not ascending up margins, transition from basal to upper cells not abrupt or V-shaped 23 23 Costa excurrent 108 Costa ending in or below apex 24 24 Margins recurved for at least part of leaf length on one or both sides 123 Leaf margins ± plane or incurved 142 155 25 Costa 1/4 or more width of leaf near base Costa narrower 26 26 Alar cells differentiated from other basal cells, often coloured, forming distinct group 161 Alar cells not differentiated 27 27 Leaf cells smooth 164 Leaf cells mamillose or papillose 187 28 Leaves tapering to long acumen, hypophysis of ± similar width to body of capsule 94. Tetraplodon (p. 516) Leaves obtuse to shortly acuminate, hypophysis as wide as or wider than body of capsule 29 29 Hypophysis of similar colour to body of capsule, antheridia borne on slender branches, marginal row of leaf cells larger than other cells 95. Aplodon (p. 517) Hypophysis purplish, wider than body of capsule or not, antheridia terminal on main stems, marginal row of leaf cells not enlarged 96. Splachnum (p. 518) 30 Plants minute, arising from persistent protonemata, capsules ± globose, ovoid or obovoid 31 Plants minute to small, protonemata not persisting, capsule shape various 32

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31 Capsules without apiculus, ring of differentiated cells delimiting lid which separates under pressure, leaves ecostate 74. Micromitrium (p. 391) Capsules with apiculus, no lid delimited, leaves ecostate or costate 75. Ephemerum (p. 391) 32 Plants persisting, leaves on sterile stems distant, spores c. 16 per capsule, 130–260 μm 13. Archidium (p. 144) Plants ephemeral or short-lived, leaves crowded, spores numerous, 16–40(−50) μm 33 33 Upper leaves and perichaetial bracts linear-lanceolate or longly acuminate 34 Leaves wider, not longly acuminate 36 34 Leaves crisped or curled when dry, cells isodiametric, papillose 42. Weissia (p. 264) Leaves erect-flexuose when dry, cells in upper part of leaf longer than wide, smooth 35 35 Perichaetial bracts longer than upper stem leaves, costa ending in apex or excurrent, cells c. 8 μm wide 14. Pleuridium (p. 147) Perichaetial bracts and upper stem leaves of ± similar length, costa ending below apex, cells 10–15 μm wide 15. Pseudephemerum (p. 148) 36 Upper leaf and perichaetial bract margins bluntly dentate from about half way up leaf, costa ending well below apex 92. Aphanorrhegma (p. 513) Margins entire, papillose or denticulate, or if dentate then only towards apex, costa extending ± to apex or excurrent 37 37 Leaves spathulate, cells 14–30 μm wide, rhizoidal gemmae abundant, sporophytes very rare 71. Leptophascum (p. 378) Leaves ovate to lanceolate, cells 9–24 μm wide, rhizoidal gemmae sparse or absent, sporophytes common 38 38 Perichaetial bract margins toothed towards apex, capsules ± spherical, with or without minute apiculus 70. Acaulon (p. 376) Perichaetial bract margins entire or papillose, capsules spherical, ovoid or ellipsoid, with apiculus or beak 39 39 Capsules exserted above perichaetial bracts, with at least one row of differentiated cells below beak, leaf cells 16–24 μm wide 65. Protobryum (p. 361) Capsules immersed or laterally exserted or if vertically exserted then leaf cells 9–15 μm wide, cells below beak not differentiated 40 40 Plants pale green, upper leaves and perichaetial bracts imbricate or convolute, concealing capsules when viewed from above laminal KOH reaction yellow 66. Phascum (p. 362) Plants green to brown or reddish green, upper leaves and perichaetial bracts erect or erect-patent, not concealing capsules when viewed from above, laminal KOH reaction red 68. Microbryum (p. 369)

Artificial key to the genera

19

41 Leaves ecostate 40. Schistostega (p. 261) Leaves costate 42 42 Lower part of leaf with conduplicate portion (sheathing lamina) 43 Lower part of leaves without conduplicate portion 44 43 Conduplicate portion of leaves about 1/2 total leaf length, capsules longly exserted, habitat various 38. Fissidens (p. 241) 1 Conduplicate portion of leaves about /3 total leaf length, capsules barely emergent, aquatic plant 39. Octodiceras (p. 260) 44 Leaf margins bordered 113. Plagiomnium (p. 628) Leaf margins unbordered 45 45 Leaves abruptly narrowed to long fine acumen, terricolous or saxicolous plants 19. Distichium (p. 160) Leaves obtuse or obtuse and apiculate, epiphytic on tree fern trunks, very rare 127. Calomnion (p. 696) 46 Plants with gemma-cups or gemma-bearing pseudopodia at stem tips 47 Plants with axillary bulbils 48 47 Plants with gemma-cups containing discoid gemmae, capsules with 4 peristome teeth 8. Tetraphis (p. 137) Plants with pseudopodia bearing clavate gemmae, capsules with 16 exostome teeth 115. Aulacomnium (p. 636) 48 Leaves on sterile stems ovate to broadly ovate, rarely lanceolate, margins entire or obscurely denticulate towards apex, cells ± rhomboid-hexagonal 105. Bryum (p. 532) Leaves lanceolate to ovate-lanceolate, margins denticulate above, cells narrowly rhomboidal 109. Pohlia (p. 593) 49 Plants medium-sized, leaf cells strongly papillose, capsules immersed or emergent 125. Hedwigia (p. 691) Plants minute, leaf cells smooth, capsules exserted 50 50 Plants not bud-like, leaf cell walls incrassate, capsules ± ellipsoid, peristome teeth 4 9. Tetrodontium (p. 139) Plants bud-like, leaf cell walls thin, capsules ± globose, peristome teeth 16 88. Discelium (p. 504) 51 Leaves with branched green filaments on adaxial side of costa 62. Aloina (p. 339) Leaves with longitudinal lamellae on adaxial side of costa at least above 52 52 Leaves pellucid, margins unbordered, entire, capsules gymnostomous 61. Pterygoneurum (p. 336) Leaves opaque or if pellucid then margins with border of elongate cells, dentate, capsules with short peristome teeth joined to epiphragm 53

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Artificial key to the genera

53 Leaves not differentiated into hyaline sheathing base and opaque blade, margins with border of narrow elongate cells 7. Atrichum (p. 133) Leaves differentiated into hyaline sheathing base and opaque blade, margins unbordered 54 54 Leaves with c. 12 sinuose lamellae on adaxial side of costa 6. Oligotrichum (p. 131) Lamellae on adaxial side of costa numerous, ± straight 3. Pogonatum, 4. Polytrichastrum, 5. Polytrichum (p. 119) 55 Leaf apices obtuse 27. Dichodontium (p. 178) Leaf apices acute to longly acuminate 56 56 Mid-leaf cells ± isodiametric, papillose or mamillose 57 Mid-leaf cells longer than wide, smooth 59 57 Leaf margins denticulate below, crenulate and irregularly toothed above, band of hyaline cells ascending up basal margins 46. Pleurochaete (p. 291) Leaf margins entire below, hyaline cells not ascending up basal margins 58 58 Leaf margins papillose-crenulate above, plants not occurring in fens 58. Didymodon (p. 315) Leaf margins dentate above, very rare fen plant 97. Paludella (p. 521) 59 Plants 3–5 cm high, leaves trifarious, narrowly triangular 98. Meesia (p. 521) Plants rarely more than 1 cm high, leaves not trifarious, abruptly narrowed above basal part to long acumen 60 60 Leaf acumens denticulate all round, cells in sheathing base rhomboidal, capsules ± erect 16. Trichodon (p. 149) Leaf acumens only denticulate at margins, cells in sheathing base rectangular to linear, capsules inclined or erect 30. Dicranella (p. 184) 61 Leaf margins 3–5-stratose, forming distinct band ± circular in section, cells hardly differing in shape from other lamina cells 62 Marginal cells elongate, differing in shape from other lamina cells, forming distinct border 63 62 Leaf margins recurved, cells strongly papillose, capsules exserted 48. Dialytrichia (p. 292) Leaf margins plane, cells smooth or faintly papillose, capsules usually immersed 73. Cinclidotus (p. 388) 63 Leaf cells ± isodiametric 64 Leaf cells longer than wide 68 64 Leaf cells smooth, pellucid 65 Leaf cells papillose, opaque 66 65 Leaf margins spinosely dentate, teeth double, costae often toothed on abaxial side 110. Mnium (p. 615)

Artificial key to the genera

66

67

68

69 70

71

72

21

Leaf margins ± entire to dentate, teeth if present single, not spinose, costae not toothed abaxially 113. Plagiomnium (p. 628) Plants 3–10 cm high, leaf margins serrulate below, coarsely serrate above 47. Paraleptodontium (p. 292) Plants to 2.5 cm high, leaf margins entire or dentate towards apex 67 Leaf margins ± entire towards apex, rhizoidal gemmae lacking, peristomes spirally twisted 64. Tortula (p. 344) Leaf margins denticulate towards apex, rhizoidal gemmae present, capsules gymnostomous 69. Hennediella (p. 372) Plants to 0.5 cm high, capsules erect, peristome rudimentary or absent, leaf cells lax, thin walled 90. Entosthodon (p. 506) Plants to 12(−15) cm high, capsules inclined to pendulous, peristome well developed, cells firm, walls at least slightly thickened 69 Leaf apices rounded, margins entire 70 Leaves acute to obtuse, margins entire or toothed 71 Costa reaching apex and confluent with border, mid-leaf cells 15–35 μm wide 111. Cinclidium (p. 622) Costa ending well below apex, mid-leaf cells 35–50 μm wide 112. Rhizomnium (p. 623) Leaf margins toothed, sometimes spinosely so or if entire then sterile shoots procumbent to arcuate 113. Plagiomnium (p. 628) Leaf margins entire or denticulate, sterile shoots erect 72 Leaf bases not very narrow, costa ± reaching apex or excurrent, bulbils lacking 105. Bryum (p. 532) Leaf bases very narrow, costa ending well below apex, spherical or ovoid bulbils, to 300 μm diameter, usually present at stem bases and developing in situ into leafy shoots 108. Epipterygium (p. 592)

73 Leaf margins and cells papillose 74 Leaf margins and cells not papillose 75 74 Perichaetial and perigonial bracts hardly differing in shape from vegetative leaves, sporophytes common, gymnostomous, protonemal gemmae present 54. Gyroweisia (p. 306) Bracts longer than vegetative leaves, bases sheathing, sporophytes very rare, peristomes spirally coiled, protonemal gemmae lacking 63. Leptobarbula (p. 343) 75 Mid-leaf cells isodiametric, setae cygneous when moist, upper leaves and perichaetial bracts linear 82. Campylostelium (p. 476) Cells longer than wide, setae straight or arcuate when moist, upper leaves and perichaetial bracts usually narrowed from ovate or lanceolate basal part to subulate acumen 173 76 Leaf cells lax, thin-walled Leaf cells firm, thin-walled to incrassate

166 77

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Artificial key to the genera

77 Plants bud-like with strongly concave imbricate leaves, costa ending below apex, peristome perfect, very rare montane plant 60. Stegonia (p. 335) Plants not bud-like, costa ending below apex to excurrent, peristome absent, imperfect or perfect, usually lowland plants 78 78 Capsules globose, mid-leaf cells rectangular to narrowly rectangular 119. Philonotis (p. 646) Capsule shape various but not globose, cells isodiametric 79 79 Leaf, margins often toothed above, setae 5–9 mm long, lid remaining attached to columella after dehiscence 69. Hennediella (p. 372) Leaf margins entire or papillose-crenulate, setae 2–5 mm long, lid falling at dehiscence 80 80 Leaves linear-lanceolate 42. Weissia (p. 264) Leaves wider 81 81 Leaf cells 7–11 μm wide, perichaetial bracts wider than upper stem leaves, sheathing, peristome well developed, spores 15–19 μm 45. Pottiopsis (p. 290) Leaf cells (9−)10–24 μm wide, perichaetial bracts of similar width to stem leaves, not sheathing, spores 20–25(−44) μm 82 82 Leaf cells 13–24 μm wide, capsule lids rostrate or longly rostrate, annulus present or not, laminal KOH reaction yellow 64. Tortula (p. 344) Leaf cells (9−)10–12(−18) μm wide, capsule lids conical or mamillate, annulus absent, laminal KOH reaction red 67. Pottia (p. 365) 83 Mid-leaf cells longer than wide 105. Bryum (p. 532) Mid-leaf cells ± isodiametric 84 84 Leaf apices hyaline when moist, whitish when dry, costa vanishing in apex 85 Costa excurrent in hyaline or very rarely reddish hair-point 90 85 Mid-leaf cells papillose, 10–16 μm wide, walls not sinuose, capsules immersed, ribbed, peristome double, exostome teeth pale 123. Orthotrichum (p. 664) Mid-leaf cells 6–12 μm wide, usually smooth, walls often sinuose, capsules immersed or exserted, peristome single, teeth reddish to brownish 86 86 Leaf margins plane, lamina with thickened plicae on either side of costa in upper half of leaf, capsules emergent, peristome teeth strongly cribrose 76. Coscinodon (p. 397) Leaf margins plane, incurved or recurved, plicae lacking, capsules immersed, emergent or exserted, peristome teeth entire to strongly cribrose 87 87 Leaf margins usually recurved, perichaetial bracts usually larger than and often differing in shape from stem leaves, capsules immersed 77. Schistidium (p. 399) Leaf margins plane, incurved or recurved, perichaetial bracts larger than stem leaves but not differing markedly in shape, capsules exserted, very rarely immersed 78. Grimmia (p. 427)

Artificial key to the genera

23

88 Leaves widest above middle 89 Leaves widest below middle 91 89 Leaves ovate-spathulate to orbicular with narrow ciliate bases, cells 50–100 μm wide, capsules gymnostomous 10. Oedipodium (p. 140) Leaves not as above, cells narrower, capsules with peristomes 90 90 Plants usually 0.2–1.0 cm high, leaves not constricted at or below middle, hair-points if present smooth, gemmae lacking, laminal KOH reaction yellow 64. Tortula (p. 344) Plants (0.2−)0.5–10.0 cm high, hyaline points if present denticulate or if smooth then leaves contracted at or below middle, gemmae sometimes present on adaxial side of leaves or stem tips or rhizoids, laminal KOH reaction red 72. Syntrichia (p. 380) 91 Leaf cells longer than wide 92 Leaf cells ± isodiametric 94 92 Leaves imbricate when moist, cells rectangular 29. Aongstroemia (p. 184) Leaves not imbricate, cells narrowly hexagonal with ± pointed ends 93 93 Stems not tomentose below, leaf cells not in radiating rows 105. Bryum (p. 532) Stems with dark brown tomentum below, leaf cells in radiating rows 114. Pseudobryum (p. 635) 94 Leaf cells ± smooth, pellucid, lumens quadrate to rounded 95 Leaf cells mamillose or papillose, pellucid or opaque, or if smooth then lumens stellate 100 95 Leaves toothed near apex, costa excurrent, very rare tree fern epiphyte 126. Leptotheca (p. 694) Plants not as above 96 96 Leaf margins denticulate to dentate above 97 Leaf margins entire or bluntly toothed above 98 97 Leaf cells 8–20 μm wide, capsules without hypophysis 23. Rhabdoweisia (p. 167) Leaf cells 20–40 μm wide capsules with hypophysis 93. Tayloria (p. 514) 98 Leaves ovate-lanceolate to broadly ovate, capsules exserted 58. Didymodon (p. 315) Leaves lingulate or narrowly lingulate to narrowly lanceolate or if ovate then capsules immersed 99 99 Leaves lingulate-lanceolate to lanceolate or ovate, capsules immersed, plants occurring within flood zone of streams and rivers 77. Schistidium (p. 399) Leaves lingulate or narrowly lanceolate, capsules exserted, plants of dry rocks 78. Grimmia (p. 427) 100 Stems with dense reddish brown tomentum or if tomentum absent then cell lumens stellate 115. Aulacomnium (p. 636) Stems not matted with tomentum, cell lumens not stellate 101

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Artificial key to the genera

101 Leaf margins denticulate to dentate 102 Leaf margins entire or papillose-crenulate 103 102 Mid-leaf cells 8–10 μm wide, marginal row of cells not differentiated from other cells 27. Dichodontium (p. 178) Mid-leaf cells 10–16(−20) μm wide, marginal rows of cells pellucid 51. Leptodontium (p. 300) 103 Leaves linear-lanceolate, margins papillose-crenulate, notched and sometimes irregularly toothed above 58. Didymodon (p. 315) Leaves not as above 104 104 Leaves incurved, strongly curved or crisped when dry 105 Leaves ± erect and/or appressed, twisted or not when dry 106 105 Leaf margins plane, apices cucullate 44. Trichostomum (p. 285) Leaf margins recurved almost to apex or narrowly recurved below, apices plane 57. Barbula (p. 312) 106 Capsules immersed or emergent, leaf margins recurved or incurved, entire or toothed above, gemmae frequently present on leaves 123. Orthotrichum (p. 664) Capsules exserted, leaf margins plane, papillose-crenulate, gemmae if present axillary 107 107 Leaf apices obtuse to subacute, basal cells rectangular, axillary gemmae lacking 55. Gymnostomum (p. 307) Leaf apices rounded, cells ± quadrate except at extreme base, ovoid to fusiform axillary gemmae frequently present 56. Molendoa (p. 310)

108 Uppermost leaves with terminal clusters of gemmae, cells papillose 109 Uppermost leaves without terminal clusters of gemmae, cells smooth or papillose 110 109 Leaves flexuose when dry, margins coarsely toothed above 51. Leptodontium (p. 300) Leaves tightly curled when dry, margins entire 124. Ulota (p. 681) 110 Leaves tapering from below middle, margins recurved ± from base to apex 111 Leaf margins plane or recurved below or if recurved to near apex then leaves broadly pointed 112 111 Leaf margins recurved, not papillose, often bluntly toothed near apex, cells smooth, pellucid, capsules inclined to horizontal, strumose 20. Ceratodon (p. 163) Leaf margins revolute, papillose, cells papillose, opaque, capsules erect, symmetrical 49. Pseudocrossidium (p. 294) 112 Leaf margins recurved below 113 Leaf margins plane 119 113 Leaf margins toothed ± from base to apex 117. Bartramia (p. 640)

Artificial key to the genera

114

115 116

117 118

119

120

121

122

25

Leaf margins entire, or papillose-crenulate, or denticulate or dentate above 114 Leaves lingulate or spathulate, widest above middle and shortly pointed, or costa widened above, capsules exserted 64. Tortula (p. 344) Leaf shape various but not as above, widest below middle, costa not widened above or if so then capsules immersed 115 Leaves shortly pointed 57. Barbula (p. 312) Leaves tapering from below middle 116 Capsules immersed, leaf cell walls ± sinuose, plants of coastal rocks 77. Schistidium (p. 399) Capsules exserted, cell walls not sinuose, habitat various but not coastal rocks 117 Leaves crisped when dry, cells smooth 26. Oncophorus (p. 176) Leaves ± straight or imbricate when dry, cells smooth or papillose 118 Leaves spirally arranged, erect-patent to patent when moist, margins entire, peristomes spirally coiled 58. Didymodon (p. 315) Leaves quinquefarious, imbricate when moist, margins serrulate above, peristomes straight 118. Conostomum (p. 645) Plants yellowish green, leaves narrowly triangular to ovate, cells bistratose above, very strongly papillose, very obscure 21. Cheilothela (p. 165) Plants not as above 120 Leaves linear-lanceolate from expanded denticulate basal part, margins plane above 41. Eucladium (p. 262) Leaf shape various, margins entire near base or if denticulate then basal part not expanded 121 Basal cells of leaves incrassate, not hyaline, axillary gemmae present although sometimes sparse 122. Zygodon (p. 659) Basal cells thin-walled and hyaline at least towards margins, gemmae absent 122 Plants to 1 cm high, autoicous, sporophytes common, peristome teeth rudimentary, fugacious 42. Weissia (p. 264) Plants 0.5–10.0 cm high, dioicous, sporophytes rare, peristome well developed 44. Trichostomum (p. 285)

123 Stems matted with brown or reddish brown tomentum, plants yellowish green to green above 124 Stems not matted with tomentum or if stems tomentose then plants reddish tinged throughout 125 124 Leaf margins papillose-crenulate, cells opaque, sporophytes on short lateral branches 53. Anoectangium (p. 304) Leaf margins entire or denticulate above, cells pellucid, sporophytes terminal 115. Aulacomnium (p. 636)

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Artificial key to the genera

125 Leaf margins entire, denticulate or dentate above but not papillose or papillose-crenulate 126 Leaf margins crenulate or papillose-crenulate above, dentate or not 140 126 Leaves ± erect, flexuose or not when dry 127 Leaves incurved, curled or crisped when dry 131 127 Cells smooth or papillose, lumens ± quadrate, capsules exserted or if immersed then smooth and leaf cell walls usually sinuose, peristomes single 128 Cells papillose, walls not sinuose, lumens ± rounded, capsules immersed, emergent or exserted, usually striate, peristomes double 134 128 Leaf margins recurved ± from base to apex, capsules strumose 20. Ceratodon (p. 163) Leaf margins recurved below or at middle, capsules not strumose 129 129 Costa 2-winged on abaxial side above, basal cells linear with sinuose walls 78. Grimmia (p. 427) Costa not 2-winged, basal cells shorter, walls not sinuose 130 130 Capsules exserted, cells papillose or smooth, walls not sinuose 58. Didymodon (p. 315) Capsules immersed, cells usually smooth, walls ± sinuose 77. Schistidium (p. 399) 131 Leaf margins entire, bases not sheathing 132 Leaf margins denticulate or dentate at least above or if entire then bases sheathing 136 132 Cell lumens ± quadrate, capsules exserted, peristomes single 133 Cell lumens ± rounded, capsules immersed, emergent or exserted, usually striate, peristomes double 134 133 Mid-leaf cells 10–14 μm wide 28. Dicranoweisia (p, 181) Mid-leaf cells 6–10 μm wide 58. Didymodon (p. 315) 134 Leaf margins narrowly recurved below, gemmae lacking, capsules exserted, calyptrae glabrous 121. Amphidium (p. 657) Leaf margins strongly recurved, gemmae sometimes present on leaves, capsules immersed, emergent or exserted, calyptrae glabrous or hairy 135 135 Capsules immersed or emergent, calyptrae glabrous to sparsely hairy, basal part of leaves not widened, concave or plicate, basal cells near margins not differentiated 123. Orthotrichum (p. 664) Capsules exserted, calyptrae hairy (sparsely so in Ulota calvescens), basal part of leaves widened, concave, sometimes plicate, basal marginal cells wider than other cells, hyaline 124. Ulota (p. 681) 136 Leaf cells usually opaque, mamillose 137 Leaf cells pellucid, smooth or mamillose 138 137 Leaves strongly crisped when dry, margins remotely denticulate above, cells partially bistratose 24. Oreoweisia (p. 170)

Artificial key to the genera

138

139

140

141

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Leaves incurved when dry, margins denticulate to dentate, cells unistratose 27. Dichodontium (p. 178) Leaf bases plicate, longitudinal walls of basal cells more strongly thickened than transverse walls 80. Ptychomitrium (p. 474) Leaf bases not plicate, walls of basal cells of ± uniform thickness 139 Leaf bases not sheathing, upper cells smooth or mamillose at least on abaxial side, capsules striate 25. Cynodontium (p. 171) Leaf bases ± sheathing, cells smooth, capsules smooth 26. Oncophorus (p. 176) Plants rusty red below, or reddish tinged, leaves usually at least bluntly dentate towards apex, or plants reddish brown throughout 50. Bryoerythrophyllum (p. 297) Plants not rusty red below, not reddish tinged or reddish brown throughout, margins not toothed above 141 Leaves oblong-lanceolate or lingulate, tapering in upper part only 57. Barbula (p. 312) Leaves broadly ovate to linear-lanceolate, tapering from middle or below 58. Didymodon (p. 315)

142 Leaf cells smooth, pellucid 143 Leaf cells mamillose or papillose, pellucid or opaque 148 143 At least upper leaves lingulate, widest at or above middle 59. Scopelophila (p. 334) Leaf shape various, widest below middle 144 144 Plants 1–10 cm high, leaf margins irregularly dentate with single or double teeth, mid-leaf cells 20–24 μm wide 110. Mnium (p. 615) Plants 0.5–3.0 cm high, leaf margins entire to dentate above, teeth single, 145 145 Leaves ± erect, flexuose when dry, lanceolate to ovate-spathulate 122. Zygodon (p. 659) Leaves crisped when dry, lingulate to ligulate or linear-lanceolate 146 146 Leaves ligulate to lingulate, acute to obtuse, margins entire to dentate 23. Rhabdoweisia (p. 167) Leaves linear-lanceolate or with linear acuminate upper part, margins entire 147 147 Mid-leaf cells mostly 6–8 μm wide, alar cells forming auricles, spores 12–20 μm 28. Dicranoweisia (p. 181) Cells 10–12 μm wide, auricles lacking, spores 40–50 μm 81. Glyphomitrium (p. 476) 148 Leaves with expanded or sheathing basal part and lanceolate or narrowly lanceolate limb 149 Leaves not differentiated into basal part and limb 150

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149 Plants small, to 1 cm high, leaf limb narrowly linear-lanceolate, margins crenulate 58. Didymodon (p. 315) Plants medium-sized to large, 2–9 cm high, leaf limb obscurely to coarsely dentate above 86. Timmia (p. 494) 150 Stems matted below with reddish brown tomentum, sporophytes on short lateral branches 53. Anoectangium (p. 304) Stems not matted with tomentum, sporophytes terminal 151 151 Plants pale or glaucous green, often coated with calcareous matter, leaf margins denticulate near base 41. Eucladium (p. 262) Plants yellowish green to dark green, not coated with calcareous matter, leaf margins usually entire below 152 152 Leaves 2–7 mm long 44. Trichostomum (p. 285) Leaves 1.0–2.5 mm long 153 153 Leaves oblong-lanceolate to lingulate, peristomes spirally twisted 57. Barbula (p. 312) Leaves linear-lanceolate to ovate, peristomes rudimentary or absent 154 154 Leaves linear to linear-lanceolate or ligulate, tapering from c. 1 /4 from base, gemmae lacking 55. Gymnostomum (p. 307) Leaves narrowly lanceolate to ovate, tapering from 1 /3 –1 /2 from base, stem gemmae present although sometimes sparse 122. Zygodon (p. 659)

155 Plants whitish when dry, costa of leaf limb in section consisting of large hyaline cells and small green cells, lamina consisting of a few rows of hyaline cells extending up margins 156 Plants not as above 157 156 Plants forming silky tufts, leaves longly tapering, alar cells inflated, very rare plant 36. Paraleucobryum (p. 237) Plants frequently forming rough textured ± hemispherical cushions, leaves shortly pointed, alar cells not differentiated, common plants 37. Leucobryum (p. 239) 157 Leaf apices rounded 98. Meesia (p. 521) Leaves with long fine acumens 158 158 Setae straight when moist, capsules pendulous, smooth, leaf cells ± linear-rhomboidal throughout 100. Leptobryum (p. 524) Setae straight or arcuate when moist, capsules inclined, striate or furrowed, cell shape various but not linear rhomboidal throughout 159 159 Capsules common, smooth when moist, strumose or not, setae straight when moist, alar cells not differentiated, plants usually 1–3 cm high 30. Dicranella (p. 184) Capsules rare (except in Campylopus introflexus), usually striate when moist, setae usually cygneous before capsule maturity, alar cells inflated and hyaline or brownish or not, plants 0.5–13.0(−25.0) cm high 160

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160 Costa denticulate on abaxial side above, longly excurrent in non-hyaline rough point, in section with band of stereids on adaxial side 34. Dicranodontium (p. 213) Costa smooth on abaxial side above, ending below apex to excurrent in smooth or hyaline point, in section with few or no stereids on adaxial side 35. Campylopus (p. 216) 161 Cells in upper part of leaf linear, costa excurrent in subulate point 83. Blindia (p. 477) Cells in upper part or leaf quadrate to rectangular, costa if excurrent not forming subulate point 162 162 Leaves abruptly narrowed above basal part to long acumen, costa longly excurrent, capsules wide-mouthed when dry and empty 31. Arctoa (p. 194) Leaves gradually tapering, costa ending below apex to excurrent but not longly so, capsules not wide-mouthed when dry and empty 163 163 Autoicous, capsules usually strumose, costa excurrent, in section without stereids or with a few on abaxial side only, montane plants 32. Kiaeria (p. 196) Dioicous, capsules not strumose, costa ending below apex to excurrent, in section with stereids or if stereids lacking then plants lowland 33. Dicranum (p. 200) 164 Leaf cells lax, thin-walled 165 Leaf cells firm, thin-walled to incrassate, firm 168 165 Leaf margins entire or denticulate above, capsules asymmetrical, inclined, spores c. 40 μm 99. Amblyodon (p. 523) leaf margins usually bluntly toothed above, capsules erect and symmetrical or if not then spores 16–28(−30) μm 166 166 Setae arcuate when moist, flexuose and twisted when dry, capsules asymmetrical, striate at maturity, sulcate when dry, mouth oblique, exostome teeth united at tips to small central disc 89. Funaria (p. 506) Plants not as above 167 167 Capsules symmetrical or gibbous and asymmetrical, lids convex, peristome present or not, calyptrae cucullate, oblique 90. Entosthodon (p. 506) Capsules symmetrical, lids apiculate or rostellate, capsules gymnostomous, calyptrae mitriform, symmetrical 91. Physcomitrium (p 510) 168 Leaf apices acuminate or subulate, consisting largely or entirely of costa 169 Leaves acute or subacute or if acuminate then acumen not consisting largely or entirely of costa 176 169 Leaf margins serrate above 116. Plagiopus (p. 639) Leaf margins entire or denticulate above 170

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170 Neck of capsule as long as body of capsule (not seen since 1883) 22. Trematodon (p. 166) Neck shorter than body of capsule or capsules absent 171 171 Leaves linear-lanceolate to linear, costa ending in or below apex, mid-leaf cells linear 102. Orthodontium (p. 526) Leaves wider, or narrowed from broad basal part to long acumen, costa ending in apex to excurrent or if ending below apex then mid-leaf cells rectangular 172 172 Plants minute, usually 1–3 mm high or if more then costa excurrent in stout subula or leaves trifarious 173 Plants usually larger, costa if excurrent not forming subula, leaves not trifarious 174 173 Setae straight or arcuate when moist, capsules smooth, leaves trifarious or not 84. Seligeria (p. 479) Setae straight, capsules striate at maturity, deeply furrowed when dry leaves not trifarious 85. Brachydontium (p. 493) 174 Leaves abruptly narrowed to long acumen, cells above basal part rectangular or narrowly rectangular 17. Ditrichum (p. 149) Leaves tapering to acumen or if abruptly narrowed then cells above basal part linear 175 175 Cells in basal part of leaf narrowly rectangular, leaves not abruptly narrowed above basal part, plants not reddish 17. Ditrichum (p. 149) Cells in basal part of leaf rectangular or if narrower then leaves abruptly narrowed above basal part or plants red tinged 30. Dicranella (p. 184) 176 Mid-leaf cells 7–10(−12) μm wide, cell ends rounded to flat 177 Mid-leaf cells 12–24 μm wide or if narrower then cells linear and/or cell ends pointed 183 177 Plants dark green, vegetative shoots slender with small distant lanceolate leaves, fertile shoots with larger crowded leaves, mid-leaf cells 8–10 μm wide, capsules immersed, cleistocarpous 13. Archidium (p. 144) Plants not as above 178 178 Plants glaucous blue-green, leaf margins bluntly dentate above, stems entwined with fungal hyphae 18. Saelania (p. 158) Plant colour various but not glaucous blue-green, leaf margins entire, denticulate or dentate above, fungal hyphae lacking 179 179 Plants with very crowded slender shoots forming dense tufts, sporophytes borne on lateral branches, plants of montane copper-containing rocks 107. Mielichhoferia (p. 591) Plants not as above, sporophytes terminal on main stems, habitat various 180 180 Leaves 1.0–2.4 mm long, linear-lanceolate to lanceolate 52. Hymenostylium (p. 302) Leaves to 1.4 mm long, ovate to lanceolate 181

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181 Leaf margins toothed 119. Philonotis (p. 646) Leaf margins entire or obscurely toothed above 182 182 Plants scattered, in patches or small tufts, to 1.5 cm high, leaves acute, margins plane or narrowly recurved below 17. Ditrichum (p. 149) Plants forming tufts or often hemispherical cushions, to 4(−7) cm high, leaves acuminate, margins recurved below 101. Catoscopium (p. 526) 183 Shoots julaceous with concave imbricate leaves when moist 184 Shoots not julaceous when moist 185 184 Leaves broadly ovate, cells narrowly hexagonal, thin-walled, 14–24 μm wide in mid-leaf, capsule mouth oblique 103. Plagiobryum (p. 528) Leaves lanceolate to ovate, cells linear-vermicular, thick-walled, 9–16 μm wide in mid-leaf capsule mouths transverse 104. Anomobryum (p. 530) 185 Robust plants arising from rhizomatous stems, upper leaves spathulate, margins dentate above 106. Rhodobryum (p. 589) Plants small to medium-sized, rhizomatous stems absent, upper leaves narrowly lanceolate to ovate, margins entire to denticulate above 186 186 Leaf margins entire or denticulate near apex, cells narrowly hexagonal or if ± linear then plants bright green or bright red 105. Bryum (p. 532) Leaf margins denticulate above, cells elongate hexagonal to linear or if rhomboidal then plants whitish green or glaucous green 109. Pohlia (p. 593) 187 Plants robust, shoots procumbent or ascending, leaves longitudinally plicate 120. Breutelia (p. 656) Plants very small to robust, shoots erect, leaves not longitudinally plicate or if so only near base 188 188 Plants forming dense tufts or cushions 189 Plants scattered, gregarious or forming lax tufts or cushions 190 189 leaves lanceolate, mid-leaf cells 8–10 m wide, smooth, capsules c. 1 mm diameter, ± black at maturity, smooth and glossy when dry 101. Catoscopium (p. 526) Leaves narrowly lanceolate, cells 8–13 m wide, mamillose, capsules larger, brown, furrowed when dry 118. Conostomum (p. 645) 190 Leaves ovate-lanceolate to ovate 119. Philonotis (p. 646) Leaves linear-lanceolate to narrowly lanceolate 191 191 Leaf cells ± smooth 116. Plagiopus (p. 639) Leaf cells mamillose 117. Bartramia (p. 640) 192 Plants robust or very robust, leaves scarious when dry or squarrose, or stems ascending, arcuate to procumbent with short spreading branches and falcate-secund leaves 211. Rhytidiadelphus (p. 925) Plants not as above, leaves not scarious or squarrose 193

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193 Leaf cells to twice as long as wide at least towards margins at widest part of leaf 199 Leaf cells more than twice as long as wide 194 194 Leaves complanate and/or margins with border of narrow elongate cells 215 Leaves not complanate, margins unbordered 195 195 Leaf apices obtuse to rounded, apiculate or not, or leaves abruptly narrowed to long apiculus from ovate to wider than long basal part 222 Leaf apices subacute to filiform 196 196 Leaves falcate-secund to circinate-secund at least at stem and branch tips 244 Leaves ± straight 197 197 Costa extending less than half way up leaf or lacking 257 Costa extending half way or more up leaf 198 198 Leaves plicate 276 Leaves not or hardly plicate 283 199 Costa extending at least half way up leaf 200 Costa extending less than half way up leaf or absent 211 200 Stems with abundant paraphyllia, regularly 1–3-pinnately branched 201 Paraphyllia few or absent, stems irregularly or pinnately branched but not 2–3-pinnate 202 201 Stems pinnately branched 155. Abietinella (p. 746) Stems 2–3-pinnately branched 156. Thuidium (p. 749) 202 Leaf margins denticulate or dentate for most of length 203 Leaf margins entire, crenulate or denticulate above 205 203 Plants slender, leaves to 1.2 mm long 147. Heterocladium (p. 731) Plants medium-sized to robust, leaves longer except on ultimate branches 204 204 Secondary stems often dendroid, branch leaves not plicate, margins dentate ± from base to apex 144. Thamnobryum (p. 724) Secondary stems not dendroid, leaves longitudinally plicate, margins with spinose often recurved teeth towards apex 138. Antitrichia (p. 714) 205 Stems and branches inrolled when dry, leaf apices rounded 141. Leptodon (p. 717) Stems and branches not inrolled when dry, leaves obtuse to acuminate 206 206 Plants robust, very rarely slender, primary stems stolonifolrm, secondary stems erect, (1−)2–8 cm long, leaf bases decurrent 154. Anomodon (p. 743) Plants not as above, leaf bases not decurrent 207 207 Plants cladocarpous, medium-sized to robust, stems usually with numerous short branches, capsules immersed 208

Artificial key to the genera

208

209 210

211 212

213 214

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Plants pleurocarpous, extremely slender to slender, branches not crowded, capsules exserted 209 Primary stems with numerous branches, branch leaves gradually tapering to acute to acuminate apex, margins narrowly recurved below 135. Cryphaea (p. 709) Primary stems sparsely branched, branch leaves shortly pointed, obtuse, margins plane 136. Dendrocryphaea (p. 711) Leaf cells smooth or faintly papillose 150. Pseudoleskeella (p. 737) Leaf cells papillose at least on abaxial side 210 Leaves not plicate, acute to obtuse, sporophytes common, epiphytic plants 149. Leskea (p. 735) Leaves slightly plicate, apices acuminate to filiform, sporophytes unknown in Britain, saxicolous plants 151. Pseudoleskea (p. 740) Plants medium-sized to large, leaves 0.8–2.5 mm long 212 Plants very slender to slender, leaves 0.3–1.2 mm long 213 Leaves longitudinally plicate, margins entire, costa absent 137. Leucodon (p. 712) Leaves not plicate, margins denticulate above, costa double, extending to 139. Pterogonium (p. 715) c. 1/4 way up leaf Leaf margins denticulate, cells papillose 147. Heterocladium (p. 731) Leaf margins entire of finely crenulate, cells smooth 214 Leaves acuminate, mid-leaf cells c. 10 μm wide 146. Habrodon (p. 730) Leaves acute, mid-leaf cells 12–16 μm wide 148. Myrinia (p. 734)

215 Leaf margins with border of narrow elongate cells 216 Leaf margins unbordered 218 216 Costa very short, mid-leaf cells 25–40 μm wide 131. Calyptrochaeta (p. 701) 217 Costa extending c. 3/4 way up leaf, mid-leaf cells 6–30 μm wide 217 Shoots to 8 cm long, leaves complanate 130. Cyclodictyon (p. 700) Shoots to 1.5 cm long, leaves spirally arranged 132. Daltonia (p. 702) 218 Mid-leaf cells 40–100 μm wide 219 Mid-leaf cells 4–22 μm wide 220 219 Leaves not dimorphic, mid-leaf cells 60–100 μm wide, frequent plant 128. Hookeria (p. 698) Leaves dimorphic, mid-leaf cells 40–60 μm wide, very rare plant 129. Achrophyllum (p. 700) 220 Costa single, extending 1/2–3/4 way up leaf, mid-leaf cells 3–4 times as long as wide 143. Homalia (p. 722) Costa very short or if not then double, cells 4–20 times as long as wide 221 221 Stems pinnately branched, branches spreading 142. Neckera (p. 719) Stems irregularly branched, branches not spreading 267

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222 Leaves abruptly narrowed to long apiculus from ovate to wider than long basal part 223 Leaf apices obtuse to rounded, apiculus if present short 228 223 Costa single, extending half way or more up leaf 224 Costa short or absent 226 224 Stems usually regularly pinnately branched, leaves imbricate when moist, plicate 183. Cirriphyllum (p. 837) Stems irregularly branched, leaves erect-patent to spreading when moist, not plicate 225 225 Acumen forming half or more total leaf length 165. Campyliadelphus (p. 775) Acumen forming 20–25% total leaf length 175. Hygrohypnum (p. 800) 226 Leaves strongly concave, imbricate when moist 140. Myurium (p. 717) Leaves weakly concave, patent to spreading or squarrose when moist 227 227 Plants slender to robust, leaves 1.2–3.6 mm long, margins entire or obscurely denticulate at widest part 164. Campylium (p. 773) Plants slender, leaves mostly 0.4–1.0 mm long, margins denticulate below or above 200. Campylophyllum (p. 889) 228 Costa extending half way or more up leaf 229 Costa extending less than half way up leaf or absent 237 229 Stems ± regularly pinnately branched, branches complanate, leaves plicate, auricles lacking 181. Pseudoscleropodium (p. 833) Branching irregular or if pinnate then branches not complanate and leaves not plicate, auricles present or not 230 230 Leaves straight, acute to obtuse 231 Leaf apices rounded or if obtuse then leaves falcate-secund 233 231 Usually robust plants of rocks subject to immersion in running water, leaves concave, margins denticulate or dentate ± from base to apex 184. Platyhypnidium (p. 840) Plants terrestrial, small to medium-sized, leaf margins entire or denticulate above 232 232 Stem leaves larger and wider than branch leaves, alar cells not forming auricles, setae papillose, lids rostrate 182. Scleropodium (p. 835) Stem and branch leaves ± similar, alar cells forming poorly defined auricles, setae smooth, lids with subulate beaks 185. Rhynchostegium (p. 843) 233 Stem leaves broadly ovate to orbicular or if narrower then falcate-secund 234 Stem leaves oblong-lanceolate or ovate-lanceolate to ovate or ovate-triangular, straight 235 234 Leaves patent to spreading when moist or falcate-secund 175. Hygrohypnum (p. 800) Leaves imbricate when moist, straight 173. Pseudocalliergon (p. 794) 235 Plants deep purplish red 167. Warnstorfia (p. 781)

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Plants yellowish green to green or brownish 236 236 Branches sparse or numerous, leaves patent to spreading when moist and when dry 169. Calliergon (p. 786) Branches absent or sparse, leaves imbricate when moist and when dry 168. Straminergon (p. 786) 237 Plants very slender, leaves 0.3–0.6 mm long, high altitude plants 191. Myurella (p. 862) Plants medium-sized to large, leaves longer, altitudinal range various 238 238 Stems pinnately branched 239 Stems irregularly branched 241 239 Stems yellowish to pale brown, leaves with poorly defined auricles 190. Entodon (p. 861) Stems reddish brown or deep red, auricles well defined 240 240 Stems reddish brown, branches not down-turned, alar cells inflated, hyaline 201. Calliergonella (p. 891) Stems deep red, branches often down-turned, alar cells rectangular, not inflated or hyaline 210. Pleurozium (p. 924) 241 Alar cells inflated, forming longly and narrowly decurrent auricles, terrestrial plants 194. Plagiothecium (p. 867) Alar cells not longly and narrowly decurrent, plants of wet or aquatic habitats 242 242 Leaves falcate-secund, often rugose, alar cells inflated, hyaline, forming small fugacious auricles 170. Scorpidium (p. 789) Leaves ± straight or if falcate-secund then not rugose, auricles if present persisting 243 243 Plants 0.5–8.0 cm long, leaves broadly ovate to ovate-orbicular or if narrower then falcate-secund 175. Hygrohypnum (p. 800) Plants to 25 cm long, leaves ovate-lanceolate, straight 173. Pseudocalliergon (p. 794) 244 Costa extending half way or more up leaf, alar cells not opaque 245 Costa absent or extending less than half way up leaf or if longer then alar cells opaque with granular contents 253 245 Leaves tapering to longly acuminate apices 246 Leaves more shortly pointed, acute to acuminate 251 246 Leaves at least weakly longitudinally plicate when moist 247 Leaves not longitudinally plicate when moist 248 247 Leaves tapering from c. 3 /4 way from base, weakly plicate, margins entire, auricles absent 171. Hamatocaulis (p. 792) Leaves tapering almost from base, strongly plicate, margins finely denticulate, auricles present 174. Sanionia (p. 797) 248 Leaf margins denticulate above 167. Warnstorfia (p. 781) Leaf margins entire or at most slightly sinuose 249

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249 Leaves with distinct auricles 166. Drepanocladus (p. 778) Auricles lacking or 2–3 alar cells inflated, hyaline, very fragile and fugacious 250 250 Plants often reddish or purplish tinged, leaves strongly falcate to circinate, outer layer of stem cells enlarged (parts of cells of the cortex remain attached to leaf bases when leaves are removed) 170. Scorpidium (p. 789) Plants green to yellowish-brown or brown, leaves falcate, cells of outer layer of stem cortex not enlarged 173. Pseudocalliergon (p. 794) 251 Leaves rugose when dry, bases not cordate, auricles not extending to costa, paraphyllia lacking 209. Rhytidium (p. 923) Leaves not rugose when dry, stem leaf bases cordate-auriculate or cordate-triangular, auricles large, extending ± to costa, paraphyllia abundant or not 252 252 Stem and branch leaves usually falcate-secund, longitudinally plicate, mid-leaf cells (6−)9–15 times as long as wide 158. Palustriella (p. 754) Stem leaves usually ± straight with secund acumens, branch leaves subfalcate to falcate-secund, leaves not plicate, cells 2–4(−6) times as long as wide 159. Cratoneuron (p. 759) 253 Leaves longitudinally plicate and/or bases cordate 254 Leaves not plicate, bases not cordate 255 254 Stems closely complanately branched, branches short, paraphyllia abundant, leaves strongly plicate 206. Ptilium (p. 916) Branching various, paraphyllia lacking, leaves not or weakly plicate 207. Ctenidium (p. 917) 255 Leaves shortly pointed, plants of fast-flowing water 175. Hygrohypnum (p. 800) Leaves tapering to apex, terrestrial plants 256 256 Leaves falcate-secund, alar cells forming distinct auricles 201. Calliergonella (p. 891) Alar cells not inflated or if so then leaves circinate-secund 205. Hypnum (p. 898)

257 Plants cladocarpous, aquatic, very robust, forming straggling tufts to 80(−150) cm long, leaves keeled or strongly concave, capsules immersed 133. Fontinalis (p. 703) Plants pleurocarpous, terrestrial, not as above, capsules exserted 258 258 Stems red or reddish brown, with abundant paraphyllia 259 Stems yellowish to green or brown or whole plant red, paraphyllia sparse or absent 261

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259 Stem leaves strongly plicate, branch leaves with single costa extending 1 /2 –3 /4 way up leaf, ending in tooth on abaxial side 213. Hylocomiastrum (p. 931) Stem leaves not or weakly plicate, costa of branch leaves thin, from almost absent to extending to half way up leaf, not ending in a tooth 260 260 Stems irregularly pinnately branched, paraphyllia 20–130 μm long 212. Loeskeobryum (p. 929) Stems regularly bipinnate, paraphyllia 200–1000 μm long 214. Hylocomium (p. 934) 261 A few alar cells inflated, hyaline, forming small non-decurrent auricles 199. Sematophyllum (p. 886) Alar cells not inflated or if so then forming longly decurrent auricles 262 262 Alar cells undifferentiated and green or colourless, or longly decurrent or forming longly decurrent auricles 263 Alar cells ± quadrate or rectangular, forming ± distinct non-decurrent group, usually 1.0–1.5 times as long as wide, or forming non-decurrent auricles 271 263 Plants exceedingly slender to slender, not reddish, leaves to c. 0.25–0.75 mm long, cells 2–6 times as long as wide 264 Plants small to robust or if slender then reddish, leaves (0.75−)1.0–5.0 mm long, cells longer 266 264 Leaves ovate to broadly ovate, acute to obtuse, cells papillose on abaxial side above 145. Pterigynandrum (p. 728) Leaves lanceolate, acuminate, cells smooth 265 265 Stem and perichaetial leaf margins entire or obscurely denticulate, capsules ± horizontal, plants autoicous 160. Amblystegium (p. 762) Margins of at least well developed leaves denticulate, perichaetial leaf margins spinosely denticulate, capsules inclined, plants dioicous 192. Platydictya (p. 863) 266 Plants forming silky red or red-tinged patches, auricles absent 193. Orthothecium (p. 865) Plants yellowish-green to green or brownish-green, not silky, auricles present or not 267 267 Leaf margins denticulate ± from base to apex 197. Herzogiella (p. 882) Leaf margins entire or denticulate only towards apex 268 268 Alar cells hyaline, longly decurrent, sometimes forming longly decurrent auricles (decurrent alar cells remain attached to stems when leaves are removed and are best viewed in situ) 194. Plagiothecium (p. 867) Alar cells green, not decurrent, but forming auricles 269 269 Leaves acute, mid-leaf cells 6–10 μm wide, 8–10 times as long as wide, calcicole 198. Taxiphyllum (p. 885) Leaf apices ± filiform, mid-leaf cells 4–7 μm wide, 10–23 times as long as wide, calcifuge to weakly calcicole 270

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Artificial key to the genera

270 Leaves rarely complanate, margins entire, fusiform axillary gemmae sometimes present 195. Isopterygiopsis (p. 880) Leaves strongly complanate, margins often denticulate near apex, flagelliform axillary branches often present and sometimes abundant 196. Pseudotaxiphyllum (p. 881) 271 Stem leaves abruptly narrowed to short point, alar cells forming orange-brown excavate group, very rare plant 176. Pictus (p. 809) Alar cells not forming excavate group or if so then leaves tapering to apex, usually common plants 272 272 Stem leaves plicate, cordate-triangular, rapidly narrowed to acute to filiform apex, setae papillose 208. Hyocomium (p. 922) Stem leaves not plicate, ovate to narrowly lanceolate, More gradually tapering to acute or acuminate apex, setae smooth 273 273 Some basal cells between alar cells and costa with flat ends, plants autoicous, fertile branches numerous, crowded, lids conical 202. Pylaisia (p. 894) Basal cells with pointed ends, plants usually dioicous, fertile branches not crowded, lids conical or rostrate 274 274 Leaf margins recurved, axillary deciduous branchlets often present at stem and branch tips 203. Platygyrium (p. 895) Leaf margins not or hardly recurved, deciduous branchlets absent 275 275 Plants autoicous, slender, stem leaves narrowly lanceolate to lanceolate, capsules strongly inclined to horizontal, curved, lid conical, very rare plant 204. Homomallium (p. 896) Plants dioicous, slender or robust, stem leaves ovate lanceolate to broadly ovate, capsules erect and straight or inclined and curved, lid rostrate, common plants 205. Hypnum (p. 898) 276 Secondary stems erect, dendroid, with terminal cluster of branches 134. Climacium (p. 709) Stems not dendroid, branches not in terminal clusters 277 277 Stems tomentose with abundant paraphyllia or rhizoids 278 Paraphyllia and/or rhizoids if present not forming tomentum 279 278 Stems irregularly branched, leaf cells smooth 172. Tomentypnum (p. 793) Stems pinnately branched, leaf cells papillose 157. Helodium (p. 754) 279 Stems with numerous paraphyllia, leaf apices acuminate, cells smooth or papillose, very rare montane plants 280 Paraphyllia lacking, leaf apices longly acuminate or filiform, cells smooth, widespread plants 281 280 Leaves gradually tapering from widest part to acuminate apex, cells papillose 152. Lescuraea (p. 741) Leaves ± abruptly narrowed to long or short acuminate apex, cells smooth 153. Ptychodium (p. 741)

Artificial key to the genera

39

281 Leaves tapering from near base to long acumen, cells linear-vermicular throughout except at basal angles 179. Homalothecium (p. 816) 1 Leaves tapering from about /4 from base, basal cells shorter and wider than cells above 282 282 Stem and branch leaves of ± similar shape, margins entire or denticulate above, lids conical 180. Brachythecium (p. 818) Stem and branch leaves differing in shape, margins denticulate ± from base to apex, lids with subulate beaks 186. Eurhynchium (p. 847)

283 Basal and alar cells isodiametric or shortly rectangular, alar cells strongly incrassate opaque 284 Basal and alar cells longer, pellucid, alar cells differentiated or not 285 284 Secondary stem erect and dendroid, or procumbent and not closely branched, costa usually extending 1/2–3/4 way up leaf, sometimes forked above 177. Isothecium (p. 810) Stems prostrate, closely branched, branches curved, costa stout, extending almost to apex, not forked 178. Scorpiurium (p. 815) 285 Alar cells opaque with granular contents 175. Hygrohypnum (p. 800) Alar cells lacking granular contents, pellucid 286 286 Stem leaves tapering to apex, mid-leaf cells short, mostly 2–6 times as long as wide 287 Mid-leaf cells of stem leaves longer or if not then leaves shortly pointed 290 287 Costae stout, more than 40 μm wide near leaf base, extending to blunt apex 161. Hygroamblystegium (p. 768) Costae thinner, not reaching leaf apex, leaves acute to acuminate 288 288 Basal marginal cells transversely rectangular, capsules erect 150. Pseudoleskeella (p. 737) Basal marginal cells longer than wide, capsules usually inclined to horizontal 289 289 Leaves (0.25−)0.6–2.2 mm long, ± entire at widest part of leaf, gemmae lacking, autoicous, sporophytes occasional to common 160. Amblystegium (p. 762) Leaves 0.3–0.7 mm long, denticulate at widest part of leaf, gemmae often present at leaf tips, dioicous, sporophytes unknown in Europe 163. Conardia (p. 772) 290 Leaves widely spreading, often subcomplanate162. Leptodictyum (p. 770) Leaves not spreading or subcomplanate 291 291 Leaves weakly to strongly asymmetrical, alar cells longly decurrent down stem 194. Plagiothecium (p. 867) Leaves symmetrical, alar cells not longly decurrent 292

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Artificial key to the genera

292 Plants usually medium-sized to robust, leaves longly tapering, often subsecund or subfalcate at stem and branch tips, plants of wet to aquatic habitats 293 Plants very slender to robust, if leaves longly tapering then plants very slender to small, habitat various 294 293 Leaf margins entire 166. Drepanocladus (p. 778) Margins denticulate above 167. Warnstorfia (p. 781) 294 Stem leaves cordate-triangular to lanceolate-triangular, tapering to acuminate or filiform apex, branch leaves differing in shape 295 Stem and branch leaves of ± similar shape 296 295 Stems irregularly branched, sporophytes rare, lids conical, rare high altitude plants 180. Brachythecium (p. 818) Stems interruptedly 1–2-pinnately branched, sporophytes frequent, lids with subulate beaks 187. Kindbergia (p. 851) 296 Plants slender or very slender, lids with subulate beaks 189. Rhynchostegiella (p. 857) Plants usually medium-sized to robust or if slender then lids conical 297 297 Stems with numerous branches, branches short, crowded or not, curved, leaves strongly concave, acute to obtuse or abruptly narrowed to acuminate apex, setae papillose 298 Branches not crowded, ± long, leaves plane to concave, apices obtuse to filiform, setae smooth or papillose 299 298 Leaves acute to obtuse, mid-leaf cells mostly 6–15 times as long as wide, lids rostrate 182. Scleropodium (p. 835) Leaves abruptly narrowed to acuminate apex, mid-leaf cells 5–6 times as long as wide, lids with subulate beaks 183. Cirriphyllum (p. 837) 299 Lids conical or rostrate, setae papillose at least above, leaves acuminate, margins usually entire or denticulate above 180. Brachythecium (p. 818) Lids with subulate beaks, setae smooth or papillose, leaves acute or occasionally acuminate, margins denticulate to dentate ± from base to apex 300 300 Leaves not or slightly concave, costa of branch leaves ending in small tooth on abaxial side, setae papillose 188. Oxyrrhynchium (p. 853) Leaves concave or very concave, costa of branch leaves not ending in tooth on abaxial side, setae smooth 301 301 Usually robust plants of rocks subject to submergence in running water, leaves 1.5–2.5 mm long 184. Platyhypnidium (p. 840) Plants small to medium-sized, terrestrial, leaves 1.0–1.5 mm long 185. Rhynchostegium (p. 843)

Division Bryophyta (Musci)

Alternation of generations heteromorphic; the sexual generation, the leafy gametophyte dominant (‘the moss plant’), the asexual generation, the sporophyte dependent on the gametophyte for survival. Gametophyte stems without xylem or phloem but sometimes with tubular conducting cells; multicellular rhizoids often present; leaves typically unistratose but sometimes thicker; costa present or not; cells isodiametric to linear. Female gametangia, archegonia, flask-shaped and containing a single female gamete; male gametangia, antheridia, producing numerous biflagellate male gametes. Fusion of gametes resulting in the development of an embryo in the venter of the archegonium. Sporophyte consisting of foot embedded in gametophyte tissue, seta, frequently with tubular conducting cells and capsule; capsules usually with stomata and photosynthetic tissue, usually dehiscing by lid, occasionally cleistocarpous, rarely by longitudinal slits; later development of capsule controlled by the calyptra derived from neck of archegonium; spores produced by meiosis in spore sac of the capsule. About 12 000 species (almost certainly an overestimate). A highly successful group of plants occurring in almost every available natural habitat except the sea.

41

Class 1 Sphagnopsida M. O. HILL Protonemata thalloid, with secondary filaments consisting of ± unbranched rows of cells with oblique dividing walls. Leafy shoots lacking rhizoids, consisting of erect main axis from which sprout fascicles of branches (in a few species there is only one much reduced branch per fascicle). Leaves ecostate, with two main types of cell. Elongate cells, dead at maturity, constitute a border. The main part of the lamina (except sometimes in perichaetial leaves) is composed of a mesh of two types of cell, chlorocysts, which are narrow and green, and hyalocysts, which are hyaline, inflated and dead at maturity of the leaf. Antheridia lateral, in leaf axils. Antherozoids biflagellate, with elongate body coiled in 2 turns of a sinistrorse spiral. Archegonia in groups of 1–5 at apex of a short specialised branch or the main stem. Setae absent, capsules joined directly to foot and exserted from perichaetium by elongation of pseudopodium composed of gametophytic tissue just below the archegonium. Capsules globose, urn-shaped when dry and empty, with a convex lid, lacking a peristome; exothecial cells brown at maturity, with scattered non-functional stomata; spore sac amphithecial in origin, overarching columella; calyptra a thin hyaline membrane, irregularly ruptured at maturity by growth of capsule. Spores arising in tetrads, each with a conspicuous triradiate scar on inner face. There are two orders, Sphagnales and Ambuchananiales. The latter contains a monotypic genus, Ambuchanania, known only from Tasmania. The ordinal status of the Ambuchananiales is still uncertain. Its basic architecture is similar to that of Sphagnum but the antheridia and archegonia are borne on the main stem and its antheridia are similar in shape to those of the Bryopsida.

1 Sphagnales Leaves unistratose. Antheridia globose, borne singly in axils of branch leaves. Archegonia in groups of 1–5 at apex of short lateral branch.

1 Sphagnaceae With the characters of the order.

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44

1 Sphagnaceae

1 SPHAGNUM L., SP. PL., 1753 Autoicous or dioicous. Stems, which are conducting, differentiated into a cortex of 1–4 layers of often hyaline parenchymatous cells surrounding a central cylinder; cylinder with thin-walled parenchymatous cells at centre, merging gradually outwards into thick-walled, smaller and often pigmented prosenchymatous cells inside cortex. Branches arising in fascicles of (1−)2–8, differentiated in most species into divergent branches which stand out from stem and bear the main photosynthetic leaves, and pendent branches appressed to stem and may assist in water conduction. Branch cellular anatomy similar to that of stems, or cells of branch cortex dimorphic, consisting of large, often protuberant retort cells, each with a pore at distal end and smaller non-protuberant cells usually without pores (branch cortex is unistratose). The stems do not fork, an enlarged fascicle branch developing into a new stem. Branch and stem leaves spirally arranged with a 2/5 phyllotaxy; fascicles of branches arise in a position adjacent to every fourth leaf in stem leaf spiral, and hence themselves arise in a reverse 2/5 ‘phyllotaxy’. Hyalocysts normally solitary, each bordered by a mesh of chlorocysts; but in the stem leaves of several species, hyalocysts form pairs or larger groups without intervening chlorocysts. In the text that follows, these groups are referred to as ‘septate hyalocysts’, as if they were a single cell with divisions. Hyalocyst cell walls may be ornamented. These ornamentations are fibrils (annular thickenings) and pores (circular, semicircular or elliptical perforations or membrane thinnings within which the cell wall is wholly or partially resorbed). Pores and, in some species, spiral fibrils often found in the stem and branch cortex. Antheridia solitary on leaf axils; ± unspecialised branches, globose, with a narrow stalk of 2–4 rows of cells. After fertilisation the perichaetial leaves grow rapidly, but the pseudopodium elongates only at maturity. Spore discharge is by an ‘airgun’ mechanism, the ripe capsule shrinking in dry weather to build up an internal pressure, reputedly 4–6 atmospheres, blowing off lid and ejecting the spores several centimetres into the air. The mechanism frequently does not work, and then the lid merely falls off, or the capsule disintegrates. Sphagnum species occur as variously coloured tussocks and ‘lawns’ in bogs, marshes, pools, wet woodland, moors and damp grassland, rarely if ever in localities with a pH exceeding 6.0. Sphagnum may be divided into about 11 sections of which 6 are represented in Britain and Ireland. About 250 species distributed through much of the world in humid climates but rare in tropical Africa. Derivation: from the Ancient Greek name of a plant of now unknown identity.

Notes on the examination of Sphagna Most species can be determined by examination of the stem leaves and branch leaves. Transverse sections of the stem are often useful, particularly in Section Subsecunda. Leaf sections are sometimes necessary, but the exposure of the chlorocysts on the abaxial and adaxial surface can often be assessed by focussing up and down on 2 leaves, one placed with the abaxial (convex) surface facing upwards, the other with the adaxial (concave) surface facing upwards. Details of pore structure are

1 Sphagnum

45

not easy to see without stain unless the pores are surrounded by a fibril ring. Dissection is often necessary to observe pores in the stem cortex, as the cylinder is opaque. Although most species can normally be determined without stain, staining simplifies identification. An aqueous solution of crystal violet or gentian violet is suitable. Scrapings from the lead of an indelible pencil dissolved in water make an effective stain. Branch leaf dimensions refer to the large leaves of the divergent branches. Pore measurements are taken longitudinally (relative to leaf shape). In the branch leaves, pore dimensions refer to those from the central part of the leaf unless otherwise stated. Pores are often absent in stem leaves except near the apex. In the stem leaves, therefore, pore dimensions refer to the part of the leaf about 2/3 –3/4 of the distance from leaf base, or higher in the leaf if necessary.

Keys to sections of Sphagnum Key 1 uses reliable structural characters but may be found difficult by beginners. Key 2 is more artificial, but is based on characters that may be found easier to use. Key 2 should be reliable with well grown plants, but may occasionally give the wrong answer when applied to abnormal growth forms. When in doubt use Key 1.

Key 1 1 Cortical cells of stems and branches with spiral fibrils (always easy to see in pendent branches) Section Sphagnum (p. 46) Cortical cells without fibrils 2 2 Chlorocysts of branch leaves triangular or trapezoid in section, broadly exposed on adaxial surface, less exposed on abaxial surface Section Acutifolia (p. 59) Chlorocysts not, or slightly exposed on adaxial surface, or if with a moderate adaxial exposure then with a greater abaxial exposure 3 3 Branch leaves denticulate at margin owing to resorption of cells in border; cells of branch cortex not dimorphic, all with a pore at distal end Section Rigida (p. 75) Branch leaves with intact border; cells of branch cortex dimorphic, consisting of large retort cells with a pore at distal end, and smaller cells which usually lack pores 4 4 Pores in middle of branch leaves large, numerous and conspicuous, 12–40 μm long Section Squarrosa (p. 55) Pores small, less than 12 μm, or if larger then not more than one per cell 5 5 Chlorocysts of branch leaves triangular or trapezoid in section, broadly exposed on abaxial surface; adaxial surface of stem leaves with extensive resorption near apex, or else with pores mostly greater than 15 μm long(use stain); stem cortex 2–3 layers, sometimes so indistinctly differentiated from central cylinder as to appear absent Section Cuspidata (p. 86)

46

1 Sphagnaceae Chlorocysts of branch leaves ± barrel-shaped in section, with a narrow exposure on abaxial surface; adaxial surface of stem leaves intact or with pores mostly less than 12 μm wide; stem cortex very distinct, 1–3 layers (often only 1) Section Subsecunda (p. 78)

Key 2 1 Branch leaves wide, cucullate, rarely less than 1 mm wide; stem cortex Section Sphagnum (p. 46) occupying 1/3 –1/2 diameter of stem Branch leaves narrow, or if wider than 1 mm then stem cortex less than 1/4 diameter of stem 2 2 Leaves without reddish pigments 3 Leaves with rose-pink, crimson or red pigments 8 3 Stem leaves with patches of narrow cells at basal angles, these being roughly the same width as cells of border, so that border, if present, appears to merge with them 4 Border distinct to base, not appearing to merge with patches of narrow cells 5 4 Branch leaves with large pores, 8–30 μm, normally 3 or more per cell; stem leaves erect and appressed to stem (except in compact forms) Section Acutifolia (p. 59) Branch leaves with pores 9 μm or less (sometimes absent), or if pores larger then not more than 1 per cell; stem leaves spreading or hanging Section Cuspidata (p. 87) 5 Stem leaves large, lingulate, 1.2–2.0 mm long, lacking fibrils Section Squarrosa (p. 55) Stem leaves various, if large and lingulate then with conspicuous fibrils 6 6 Stem leaves spreading or hanging 7 Stem leaves erect and appressed to stem 8 7 Branch leaves denticulate because of resorption of outer part of walls in border; pores medium-sized or large, 5–25 μm Section Rigida (p. 75) Branch leaves entire, with an intact border; pores small, 2–6 μm, or sometimes absent Section Subsecunda (p. 78) 8 Pores small, less than 6 μm; stem cortex with a single layer of hyaline cells Section Subsecunda (p. 78) Pores 8–30 μm; stem cortex 2–4 layers Section Acutifolia (p. 59) Section 1 Sphagnum Plants medium-sized or robust. Stems usually 0.6–1.2 mm diameter; cortex 3–4 layers, hyaline, (60−)100–300 μm wide, occupying about half diameter of stem; cortical cell walls with sinistrally spiralling fibrils (sometimes absent in surface layer but always present in inner cells); outer surface with 1–8 pores per cell; diameter of cortical cells measured at right-angles to radius 25–90(−120) μm, numerous cells always exceeding 50 μm; cylinder strongly differentiated from cortex. Branches in fascicles of 3–7, (1−)2(−3) divergent, 1–4 pendent; branch cortex

Section Sphagnum

47

with 0–1 pores per cell, the cells not dimorphic, their walls with sinistrally spiralling fibrils (not always obvious in divergent branches, easily seen in pendent branches). Stem leaves erect or hanging, usually 1.1–2.0 × 0.7–1.4 mm, ± rectangular; border 2–5 cells wide, rather ill-defined, denticulate along sides of leaf, becoming irregular and almost unrecognisable near apex; cells of border 8–14 μm wide, those at margin extensively resorbed on outer surface and usually represented only by a resorption furrow, or sometimes ± intact near base; hyalocysts septate or not; abaxial surface almost completely resorbed and lacking through much of leaf; adaxial surface intact, with or without fibrils in upper leaf. Branch leaves cucullate, elliptic or broadly ovate, usually 1.1–2.8 × 0.9–1.9 mm; margin denticulate, the border 1 cell wide, completely resorbed on outer surface and represented only by a resorption furrow (margin appears denticulate owing to projection of transverse cell walls which persist after destruction of border); chlorocysts in section varying from completely enclosed on both surfaces to broadly exposed on adaxial surface with a slight exposure on abaxial surface; hyalocysts in cucullate region near leaf apex wider than long, their abaxial surface with a large membrane gap in distal half of cell, so that leaf apex appears scabrous because of projecting cell walls; abaxial pores in mid-leaf 8–25 μm, (0−)3–6(−16) per cell, in mid-leaf normally occurring in triplets, one at each corner of three adjacent hyalocysts, towards margin of leaf (and rarely in centre) more numerous and not confined to cell angles; adaxial pores few or absent in mid-leaf, more numerous towards margins, positioned along commissures. Antheridia on divergent branches. Perichaetial leaves oblong, rounded and tattered at apex; border 2–3 cells wide, ± intact in lower half of leaf, strongly resorbed above and absent at apex; hyalocysts fibrillose and porose near apex, not resorbed on either surface below, above ± lacunose on abaxial surface.

Key to Sphagnum Section Sphagnum 1 Inside walls of hyalocysts of branch leaves ornamented with papillae or lamellae where they abut on chlorocysts, so that in surface view of leaf the chlorocysts appear to be papillose or lamellate; cells near centre of stem leaves mostly septate; plants green, yellowish, ochre or brown with no red tinge 2 Surface of chlorocysts of branch leaves appearing smooth; cells near centre of stem leaves not or hardly septate; plants green, yellowish, pinkish-orange or red 4 2 Surface of chlorocysts appearing papillose; chlorocysts in cross-section barrel-shaped with bulging sides and thick cell walls on adaxial surface 3. S. papillosum Surface of chlorocysts with transverse lamellae (comb-fibrils), which project into hyalocysts like the teeth of a comb; chlorocysts in cross-section triangular, with straight sides, lacking thickened adaxial cell walls 3 3 Branches in fascicles of 3; stem leaves with comb-fibrils in upper part; usually in compact brownish hummocks 1. S. austinii

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Branches in fascicles of 4; stem leaves lacking comb-fibrils; usually lax green or yellowish plants in loose tufts 2. S. affine 4 Chlorocysts of branch leaves completely enclosed on both surfaces of leaf; plants dull crimson, rarely completely green 5. S. magellanicum Chlorocysts of branch leaves reaching surface on both sides of leaf, often fully exposed on adaxial face; colour various, sometimes pinkish-orange or brick-red, but not dull crimson 3. S. palustre 1 S. austinii Sull. ex Aust., Musci Appalach., 1870 (Fig. 2) S. imbricatum Hornsch. ex Russow ssp. austinii (Sull. ex Aust.) Flatberg Dioicous. Shoots to 15 cm long, usually in compact, reddish brown, mottled hummocks, rarely in lax brownish tussocks. Stems (0.3−)0.5–0.9 mm diameter; cortex 3–4 layers; pores on outer surface 1–4 per cell; cylinder dark brown. Branches 3 per fascicle, 2 divergent, 1 pendent, the divergent branches often somewhat curved; fibrils of cortex 2–3 times more numerous on inner surface adjacent to cylinder than they are on outer surface (in other European members of Section Sphagnum except S. affine they are equally numerous on both surfaces). Stem leaves 1.1– 1.8 × 0.8–1.0 mm, lingulate or rectangular; cells near middle of leaf 50–100% septate; cells near leaf apex with short comb-fibrils (see below). Branch leaves 1.3–2.2 × 0.9–1.5 mm, concave, ovate, mostly less than 0.7 times as wide as long, cucullate; thickness of lamina in mid-leaf 25–42 μm in middle of hyalocysts, 12– 16 μm where these abut on chlorocysts; internal walls of hyalocysts where these abut on chlorocysts with conspicuous comb-fibrils, i.e. lamellae that mostly run perpendicular to the chlorocysts, projecting to give a comb-like appearance to the chlorocysts in surface view of leaf; chlorocysts in section equilaterally triangular, straight-sided, reaching surface on both sides of leaf, broadly exposed on adaxial face; abaxial pores in mid leaf 11–18 μm, (0−)3–8 per cell, adaxial pores usually absent in mid-leaf, occasionally to 5 per cell. Antheridial leaves densely imbricate. Capsules very rare, summer. Ombrotrophic bogs on deep peat. 0–500 m. Devon to Shetland, confined to the north and west; widespread in Ireland; local and seldom abundant. Sub-fossil S. austinii is a major component of the peat of raised bogs in many parts of the British Isles. 35, H20. GB64 + 12∗ , IR42 + 6∗ . Hyperoceanic Temperate. An oceanic species, found near coasts of N. W. Europe, and N. E. and N. W. North America; another subspecies occurs in arctic Asia and arctic N. America. Sphagnum austinii and S. affine are components of the S. imbricatum complex, which was monographed by K. I. Flatberg, K. Norske Vidensk. Selsk. Skr. 3, 1–80, 1984. The combfibrils in the branch leaves are sometimes ± obsolete except near the margins at the base. The characteristic ornamentation of the inner surface of the branch cortex is, however, constant. In the field, the mottled colour and often slightly curved branches are useful characters. Lax forms can be distinguished by having uniformly 3 branches per fascicle.

Section Sphagnum

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Fig. 2 1–5, Sphagnum austinii: 1, divergent branch leaves; 2, stem leaf; 3, 4, cells at middle of divergent branch leaf, adaxial and abaxial side; 5, divergent branch leaf section. 6–11, S. affine: 6, moist fascicle (×4); 7, divergent branch leaves; 8, stem leaf; 9, 10, cells at middle of divergent branch leaf, adaxial and abaxial side; 11, divergent branch leaf section. Leaves ×27, cells ×280.

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2 S. affine Renauld & Cardot, Rev. Bryol., 1885 (Fig. 2) S. imbricatum Hornsch. ex Russow ssp. affine (Renauld & Cardot) Flatberg Dioicous. Shoots to 15 cm long, green or yellowish, forming lax tussocks or ‘lawns’. General anatomy similar to that of S. austinii, differing as follows. Inner surface of stem cortex with densely-packed fibrils resembling those of the inner surface of branch cortex (S. austinii has such fibrils in the branches but not the stems). Branches in fascicles of 4, 2 divergent, 2 pendent, the divergent branches not curved. Stem leaves lacking comb-fibrils, hyalocysts in upper part of leaf more septate than in S. austinii, often divided into groups of 3–4. Branch leaves 1.1– 2.0 × 0.9–1.6 mm, broadly ovate, mostly more than 0.7 times as wide as long. Antheridial leaves densely imbricate, ochre. Spores 24–28 μm. Capsules rare, summer. Ditches, marshes, basic seepages and in-filling lakes. 0–400 m. Occasional to frequent in high-rainfall parts of western Britain from N. Wales northwards; very rare in eastern Scotland and S. W. Ireland, an old record from Armagh. 21, H3. GB44 + 9∗ , IR2 + 1∗ . Suboceanic Boreal-montane. W. and C. Europe north to Iceland, Azores, eastern North America, Central America, Cuba. In the field it resembles S. papillosum, but can with experience usually be recognised by the combination of smaller size, stronger colour and more tapering branches. For further information see M. O. Hill, J. Bryol. 15, 109–15, 1988.

3 S. papillosum Lindb., Acta Soc. Sci. Fenn., 1872 (Fig. 3) Dioicous. Shoots to 20 cm long, green, yellowish or ochre, forming hummocks or loose tussocks. Stems 0.7–1.0 mm diameter; cortex 3–4 layers; pores on outer surface 1–5(−6) per cell; cylinder green or brown. Branches (3−)4 per fascicle, (1−)2 divergent, (1−)2 pendent. Stem leaves 1.1–1.8 × 0.8–1.4 mm, obovate, lingulate or ± rectangular; cells near middle of leaf 50–100% septate, or rarely not septate. Branch leaves 1.5–2.5 × 1.3–1.9 mm, concave, broadly ovate, apices cucullate, wide and rounded; lamina in mid-leaf 27–48 μm thick in middle of hyalocysts, (16−)20–32 μm thick where these abut on chlorocysts; internal walls of hyalocysts where these abut on chlorocysts papillose; chlorocysts in section reaching surface on both sides of leaf, either barrel-shaped and moderately exposed on adaxial face or lens-shaped with a negligible exposure on adaxial face; abaxial pores in midleaf 13–22 μm, 3–10 per cell; adaxial pores absent in mid-leaf. Antheridial leaves densely imbricate, ochre. Spores 27–30 μm. Capsules occasional, summer. n = 19, 38 + 4 m∗ . On moors and bogs, mainly in strongly acid localities, but sometimes in acidic fens. 0–1050 m. Abundant in the north and west, local in the southeast. 99, H40. GB908 + 64∗ , IR241 + 14∗ . European Boreo-temperate. Suboceanic, discontinuously circumboreal, extending south to India and the Carolinas. Generally easy to recognise, with a characteristic ochre colour and stubby branches. Partially shaded forms strongly resemble S. palustre, and cannot always be distinguished from it in the field. Well grown plants of S. palustre differ from S. papillosum in having 3–4 pendent branches per fascicle; but the compact forms that are most likely to be confused with

Section Sphagnum

51

Fig. 3 1–5, Sphagnum papillosum: 1, divergent branch leaves; 2, stem leaf; 3, 4, cells at middle of divergent branch leaf, abaxial and adaxial side; 5, divergent branch leaf section. 6–8, S. palustre var. centrale: 6, 7, cells at middle of divergent branch leaf, adaxial and abaxial side; 8, divergent branch leaf section. Leaves ×27, cells ×280.

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S. papillosum have only (1−)2 pendent branches, so the difference is not much use in practice. Compact forms of both species superficially resemble S. compactum, but differ in the much larger stem leaves and more cucullate branch leaves. For differences from S. affine see notes under that species. Weakly papillose forms are rare but can be confusing; in these the papillae are ± obsolete except near the margins in the lower part of the leaf.

4 S. palustre L., Sp. Pl., 1753 Dioicous. Shoots to 25 cm long, variously green, pinkish orange or slightly yellowish, forming whitish or green tussocks or untidy ‘lawns’. Stems 0.6–1.2 mm diameter; cortex 3–4 layers; pores on outer surface 1–8(−10) per cell; cylinder green or brown. Branches (3−)4–6(−7) per fascicle, 2(−3) divergent, (1−)2–4 pendent. Stem leaves 1.2–2.0 × 0.9–1.4 mm, obovate, lingulate or ± rectangular; cells not septate, or rarely a few septate near middle of leaf. Branch leaves 1.7– 2.8 × 1.1–1.8 mm, concave, ovate or broadly ovate, the apex cucullate, normally wide and rounded, but in shade forms narrower, ± acute and somewhat squarrose (though the extreme tip is always cucullate); lamina in mid-leaf 30–50 μm thick in middle of hyalocysts, 19–30 μm thick where these abut on chlorocysts; internal walls of hyalocysts lacking papillae or lamellae; chlorocysts reaching surface on both sides of leaf, in section variously triangular or barrel-shaped and exposed on adaxial face or lens-shaped with negligible adaxial exposure; abaxial pores in mid-leaf variable, 8–25 μm, 3–16 per cell; adaxial pores in mid-leaf absent or very few. Antheridial leaves densely imbricate, bright pinkish-orange in autumn and winter, changing to yellowish in summer. Spores 26–32 μm. Capsules occasional, summer. Chlorocysts in section triangular, with straight sides Chlorocysts in section barrel- or lens-shaped, with bulging sides Var. palustre S. cymbifolium Hedw.

var. palustre var. centrale (Fig. 4)

Chlorocysts of branch leaves in section narrowly triangular, with straight sides and cell walls unthickened on adaxial leaf surface. n = 38, 38 + 4 m∗ . Mesotrophic marshes, streamsides and wet woodland. 0–1000 m. Abundant in the north and west, frequent in the south-east. 111, H35, C. GB1180 + 83∗ , IR189 + 4∗ , C1. Circumpolar Boreo-temperate. Suboceanic, discontinuously circumpolar, mainly in the southern boreal and northern broad-leaved forest zones, extending south to the Himalayas, Azores, Algeria, Mexico. Var. centrale (C. E. O. Jensen) A. Eddy in Daniels & Eddy, Handb. Eur. Sphagna, 1985 (Fig. 3) S. centrale C. E. O. Jensen, S. subbicolor auct. non Hampe Chlorocysts of branch leaves in section barrel- or lens-shaped, with bulging sides and cell walls thickened on adaxial surface. n = c. 38. Scattered localities in

Section Sphagnum

53

Fig. 4 Sphagnum palustre var. palustre: 1, moist fascicle with dehisced capsules (×1.5); 2, divergent branch leaves); 3, stem leaf; 4, 5, cells at middle of divergent branch leaf, abaxial and adaxial side; 6, margin of divergent branch leaf near apex showing resorption of cells; 7, marginal cells at widest part of stem leaf; 8, divergent branch leaf section; 9, stem cortex, surface view; 10, divergent branch cortex, surface view; 11, stem section. Leaves ×27, leaf cells ×280, cortex cells ×110.

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1 Sphagnaceae

England, Wales and the Isle of Man, distribution very poorly known, Caernarfon, old records from W. Lancashire, N. E. Yorkshire, I. of Man. 4. Circumpolar, mainly in the boreal zone, with a subcontinental distribution in Europe. In the field Sphagnum palustre can be confused with S. denticulatum, S. compactum and S. squarrosum; but the members of Section Sphagnum are distinct not only in the cucullate apex of the branch leaves, but also in the wide hyaline cortex, occupying 1/3 –1/2 the diameter of the stem (pull stem in half to see this). The field distinction between S. papillosum and S. palustre can be difficult, though with experience most plants can be named correctly. The branches of S. palustre are more tapering, its colour is more commonly green, and the branches at the centre of the capitulum are commonly pinkishorange, not ochre as in S. papillosum. For differences from S. magellanicum see under that species. Var. centrale, as it occurs in Britain, appears to be little more than an uncommon morph with no correlated characters. One of the Isle of Man specimens has capsules. Intermediates, with chlorocysts of both types in a single leaf, are sometimes found. Var. centrale is the common form in more northern and continental areas. The majority of authors both in Europe and North America treat it as a species.

5 S. magellanicum Brid., Muscol. Recent. II, 1798 S. medium Limpr.

(Fig. 5)

Dioicous. Shoots to 20 cm long, dull crimson or occasionally green, forming tussocks or loose carpets. Stems 0.7–1.1 mm diameter, cortex 3–4 layers; pores on outer surface (0−)1(−3) per cell; cylinder blackish-red. Branches 3–5 per fascicle, 2 divergent, 1–3 pendent. Stem leaves 1.4–1.8 × 0.7–1.2 mm, ± rectangular; cells near middle of leaf not septate, or rarely a few septate. Branch leaves 1.7– 2.7 × 1.5–2.0 mm, concave, broadly ovate, the apex wide and rounded, cucullate; thickness of lamina in mid-leaf 30–45 μm in middle of hyalocysts, 27–40 μm at cell junctions; internal walls of hyalocysts without papillae or lamellae; chlorocysts in section lens-shaped, completely enclosed by the hyalocysts and not reaching either face of leaf; abaxial pores in mid-leaf 11–19 μm, (0−)3–6 per cell; adaxial pores in mid-leaf absent or very few. Antheridial leaves densely imbricate, crimson. Spores 26–30 μm. Capsules rare, summer. n = 18 + 3−4 m, 19. On deep-peat bogs and valley bogs, usually mixed with S. papillosum but much less common. 0–1030 m. Throughout the British Isles, but rare in south-east England. 68, H33. GB375 + 35∗ , IR120 + 10∗ . Circumpolar Boreal-montane. Circumpolar, mainly boreal, also C. and S. America to Tierra del Fuego, and scattered elsewhere in the Southern Hemisphere and tropics. The branches are stubby, so that the habit resembles S. papillosum. The dull crimson colour, once known, is unmistakable, but can easily be confused by the inexperienced with the pinkish orange (occasionally brick-red) developed by S. palustre in autumn. S. magellanicum changes colour in weak alkali, turning a mud brown; the colour of S. palustre is hardly altered.

Section Squarrosa

55

Fig. 5 Sphagnum magellanicum: 1, divergent branch leaves; 2, stem leaf; 3, 4, cells at middle of divergent branch leaf, abaxial and adaxial side; 5, divergent branch leaf section. Leaves ×27, cells ×280.

Section 2 Squarrosa (Russow) Schimp., Syn. Musc. Eur. 2, 1876 Plants slender to robust. Stems usually 0.5–1.2 mm diameter; cortex 2–4 layers, hyaline, 30–70 μm wide, cell walls without fibrils; outer surface mostly without pores, or with scattered patches of cells having a single indistinct pore at upper end; diameter of cortical cells measured at right-angles to radius, 15–55 μm; cylinder strongly differentiated from cortex. Branches in fascicles of 4–6(−7), 2–3 (−4) divergent, 2–3(−4) pendent; branch cortex with 0–1 pores per cell, the cells dimorphic (dimorphism often weak in divergent branches), cell walls without spiral fibrils; retort cells flat or with an indistinct neck, in groups of 1–4(−6). Stem leaves hanging, spreading or erect, usually 1.2–2.0 × 0.8–1.3 mm, lingulate; border 2–6 cells wide, ceasing below rounded region of apex where marginal cells are resorbed and fimbriate; patches of narrow cells at basal angles absent; hyalocysts hardly septate except near basal angles, lacking fibrils, or rarely with weak

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fibrils near basal angles; abaxial surface almost completely resorbed, lacking or (less often) very thin; adaxial surface ± intact. Branch leaves ovate or broadly ovate, not cucullate, usually 1.0–3.1 × 0.5–1.8 mm, with an intact border of 1–3 narrow cells; chlorocysts ± trapezoid in section, more exposed on abaxial than adaxial surface; hyalocysts near apex longer than broad, their abaxial surface often with a pore at distal angle but not lacunose; abaxial pores in mid-leaf 12–40 μm, (0−)1–12(−16) per cell, not normally in triplets at cell angles, sometimes centrally placed and coalescing into large membrane gaps; adaxial pores mostly along commissures, 0–11(−15) per cell in mid-leaf, more numerous towards margins, near apex commonly in triplets, one at each corner of 3 adjacent hyalocysts. Antheridia on divergent branches. Perichaetial leaves oblong or cuneate; border 1–2 cells wide, intact in lower half of leaf, ± resorbed in upper half and absent at apex. Hyalocysts lacking fibrils and pores; abaxial surface extensively resorbed, thin or lacking throughout leaf; adaxial surface ± intact.

Key to Sphagnum Section Squarrosa 1 Robust green or slightly brownish plants; stems 0.7–1.2 mm diameter; branch leaves usually squarrose, 1.7–3.1 × 1.0–1.8 mm 6. S. squarrosum Plants slender or medium-sized, greenish yellow or brown, rarely completely green; stems 0.5–0.7 mm diameter; branch leaves ± appressed, rarely squarrose, 1.0–2.3 × 0.5–1.2 mm 7. S. teres 6 S. squarrosum Crome, Samml. Deutschl. Laubm., 1803 (Fig. 6) Autoicous. Shoots to 20 cm long, green or somewhat brownish, with mediumsized terminal buds, forming untidy ‘lawns’. Stems 0.7–1.2 mm diameter; cortex 2–4 layers; outer surface without pores, or with pores in a few scattered patches of cells; cylinder green or brown. Branches 4–6(−7) per fascicle, 2–3(−4) divergent, 2–3(−4) pendent; retort cells in groups of 1–6, often weakly differentiated from other cells on divergent branches. Stem leaves erect, spreading or hanging, 1.7–2.0 × 0.8–1.3 mm, lingulate; border 2–6 cells wide, ceasing below rounded region of apex, patches of narrow cells at basal angles absent or rarely to about 8 cells wide; hyalocysts near basal angles often septate, above not, or hardly septate; abaxial surface lacking or very thin; adaxial surface intact, without fibrils or pores. Branch leaves 1.7–3.1 × 1.0–1.8 mm, ovate or broadly ovate, apices normally bent back sharply in mid-leaf so that leaf is strongly squarrose; border 1–3 cells wide; chlorocysts in section ± trapezoid with bulging sides, the greater exposure being on the abaxial surface; interior walls of hyalocysts where they abut on chlorocysts obscurely papillose; abaxial pores in mid-leaf variable, 13–50 μm, (0−)1– 12(−16) per cell, perforate or imperforate, centrally placed or along commissures; adaxial pores in mid-leaf imperforate, 12–25 μm, 0–11(−15) per cell. Antheridial leaves not markedly squarrose, green or slightly yellowish. Perichaetial leaves with the characters of the Section, cuneate, with truncate or retuse apex. Spores 27–30 μm. Capsules common, summer. n = 19 + 2 m, 19 + 4 m, 38 + 4 m∗ .

Section Squarrosa

57

Fig. 6 1–6, Sphagnum squarrosum: 1, moist fascicle; 2, divergent branch leaves; 3, stem leaf; 4, 5, cells at middle of divergent branch leaf, adaxial and abaxial side; 6, divergent branch leaf section. 7–12, S. teres: 7, moist fascicle; 8, divergent branch leaves; 9, stem leaves; 10, 11, cells at middle of divergent branch leaf, abaxial and adaxial side; 12, divergent branch leaf section. Fascicles ×1.5, leaves ×27, cells ×280.

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Among rushes and other large higher plants, sometimes abundant in swampy woodland or on swampy ground by lakes, or in smaller quantity in upland flushes, confined to markedly eutrophic situations. Mainly lowland but occasional in the mountains and ascending to 1030 m in W. Inverness. Frequent to common throughout the British Isles. 103, H34. GB610 + 78∗ , IR54 + 14∗ . Circumpolar Wideboreal. Circumpolar, arctic, boreal and cool temperate. With its robust habit, green colour and strongly squarrose branch leaves S. squarrosum is usually easy to recognise in the field. It can resemble shade forms of S. palustre but differs in the relatively narrow stem cortex (occupying 1/4 of the diameter of the stem, as opposed to nearly half in S. palustre). S. compactum occasionally has squarrose branch leaves but differs in its small stem leaves. For distinction from S. teres see under that species.

7 S. teres (Schimp.) Ångstr. in Hartm., Skand. Fl., 1861 S. squarrosum var. teres Schimp.

(Fig. 6)

Dioicous. Shoots to 20 cm long, green, yellowish or brown, with large terminal buds, forming ‘lawns’ and loose tufts. Stems 0.5–0.7 mm diameter; cortex 2–4 layers; outer surface with indistinct pores in scattered patches of cells; cylinder brown. Branches 4–5(−7) per fascicle, usually 3 divergent, 2 pendent; retort cells in groups of 1–2(−5). Stem leaves erect, spreading or hanging, 1.2–2.0 × 0.8– 1.1 mm, lingulate; border 2–5 cells wide, ceasing below rounded region of apex; patches of narrow cells at basal angles absent; hyalocysts near basal angles often septate, above not or hardly septate; abaxial surface lacking or very thin; adaxial surface intact, without fibrils or pores. Branch leaves 1.0–2.3 × 0.5–1.2 mm, ovate, not or only slightly squarrose, or in shade forms sometimes strongly squarrose; border 1–3 cells wide; chlorocysts in section trapezoid with the greater exposure on the abaxial surface; interior walls of hyalocysts where they abut on chlorocysts sometimes finely papillose; abaxial pores in mid-leaf 12–40 μm, 3–8 per cell, often centrally placed and coalescing into ± extensive membrane gaps; adaxial pores in mid-leaf imperforate, 12–25 μm, 1–7 per cell, or sometimes absent (though numerous near margins). Antheridial leaves greenish. Perichaetial leaves with the characters of the Section, oblong with a retuse apex. Spores 24–26 μm. Capsules rare, summer. n = 19 + 4 m, 19 + 5 m. Among rushes and small sedges, indicative of base-rich flushing. 0–1050 m. Throughout the British Isles; rare in the lowlands, frequent to common in the uplands. 66, H7. GB251 + 51∗ , IR8 + 3∗ . Circumpolar Boreo-arctic Montane. Circumpolar, mainly arctic and boreal, extending south in mountains to Italy and California. Can normally be recognised in the field by its rather rigid branches, with leaves slightly bent backwards in mid-leaf, the yellowish or brown colour, and large terminal buds. It can have a strong superficial resemblance to S. girgensohnii, but differs when well illuminated in its dark brown stems and in normally having 3+2 branches per fascicle. Robust greenish forms can be exceedingly hard to separate from S. squarrosum. The best policy is to make a careful search in the field to find typical S. teres or S. squarrosum in the immediate vicinity.

Section Acutifolia

59

There is no reliable microscopic distinction, and differences given by various authors break down when applied to the apparently intermediate forms. It should be appreciated, however, that these forms are unusual, and that S. teres normally looks so different from S. squarrosum that their close relationship is not apparent without microscopic examination.

Section 3 Acutifolia Wilson, Bryol. Brit., 1855 Plants slender to medium-sized, with red or brown pigments. Stems usually 0.3– 0.9 mm diameter; cortex 2–4 layers, hyaline, 40–200 μm wide, cell walls without fibrils; outer surface without pores or with 1(−2) pores per cell, diameter of cortical cells measured at right-angles to radius, 20–85 μm; cylinder strongly differentiated from cortex. Branches in fascicles of 3–5(−6), 2–3 divergent, (0−)1–2(−3) pendent; branch cortex with clearly dimorphic cells, cell walls without spiral fibrils; retort cells with a moderate to strong neck, in groups of 1(−2), except in S. molle. Stem leaves erect, or in compact forms spreading, usually 0.8–1.7 × 0.5–1.2 mm (larger in the nearly isophyllous S. molle), spathulate, triangular or lingulate; border 2–9 cells wide, entire or denticulate (± lacking in S. fimbriatum); patches of narrow cells at basal angles occupying (0−)20–80% of leaf base; hyalocysts in upper leaf (0−)20–100% septate, with or without fibrils, extensively resorbed on adaxial surface, abaxial surface in most species ± intact. Branch leaves ovate or narrowly ovate, not cucullate, usually 0.8–2.7 × 0.4–1.8 mm; border 1–3(−4) cells wide, intact (except S. molle); chlorocysts triangular in section, broadly exposed on adaxial surface; hyalocysts near apex longer than broad, not lacunose; abaxial pores in mid-leaf 8–30(−55) μm, 1–16 per cell, towards leaf apex often in triplets, one at each corner of 3 adjacent hyalocysts; adaxial pores in mid-leaf often absent, when present centrally placed, 10–20 μm, to 5 per cell, more numerous towards margins. Antheridia on divergent branches. Perichaetial leaves ovate or oblong; border intact to apex; hyalocysts intact on both surfaces, lacking fibrils and pores (except sometimes S. molle).

Key to Sphagnum Section Acutifolia 1 Branch leaves denticulate at margin in upper half owing to resorption of cell walls in border; stem leaves strongly fibrillose, 1.5–2.8 mm long 17. S. molle Branch leaves with intact border; stem leaves to 1.4 mm long, or if longer then lacking fibrils 2 2 Stem leaves triangular or triangular-lingulate, margin plane or inrolled at apex 3 Stem leaves lingulate or spathulate, margin ± plane at apex 6 3 Fascicles mainly with 4–5 branches, some or most with 3 divergent branches; stem cylinder predominantly green with at most a few red flecks, invariably green in plants whose leaves are green; stem cortex with scattered pores (use stain); leaves on divergent branches normally 5-ranked 11. S. quinquefarium

60

4

5

6

7

8

9

10

1 Sphagnaceae Fascicles mainly with 3–4 branches, rarely with more than 2 divergent branches; stem cylinder usually with red or brown pigment, even in plants whose leaves are green; stem cortex without pores, or if with pores then branch leaves not 5-ranked 4 Stem leaves without fibrils or fibrils weak, apices acute with inrolled leaf margins; branch leaves (0.9−)1.2–2.7 mm long 5 Stem leaves with conspicuous fibrils, or if not then apices ± plane; branch leaves (0.6−)0.9–1.4 mm long 10 Fascicles with 3(−4) branches, none or very few having more than 1 pendent branch; stem leaves mostly less than 0.6 times as wide as long, cells in upper part 80–100% septate, many divided more than once; stem cortex lacking pores 15. S. subnitens Fascicles with 3–4 branches, many with 2 pendent branches; stem leaves mostly more than 0.6 times as wide as long, cells less septate, few divided more than once; stem cortex with scattered pores 16. S. skyense Brown plants with dark brown stems 14. S. fuscum Plants green or red, with pale or reddish stems, or if plants slightly brownish, then stems pale 7 Green or slightly brownish plants with no trace of red pigment; stem leaves lacking fibrils, often extensively fimbriate near apex, equally resorbed on both surfaces so that when stained extensive gaps are visible both near apex and at base 8 Red pigment often present; stem leaves with or without fibrils, not or only slightly fimbriate near apex, with extensive resorption only on adaxial surface and hence not showing gaps when stained 9 Stem leaves spathulate, widest above base, border lacking or if present ceasing at or below middle of leaf 8. S. fimbriatum Stem leaves lingulate, widest at base, border continued to near apex 9. S. girgensohnii Stem leaves lingulate with broad rounded apices; many cells in middle part of branch leaves having more than 8 abaxial pores; surface of stem cortex with scattered pores (use stain) 10. S. russowii Stem leaves various, sometimes lingulate with broad rounded apices; cells in middle part of branch leaves with 3–7 abaxial pores, rarely a few cells with up to 9 pores; stem cortex without pores 10 Pores on abaxial side of branch leaves near apex small, 2–6(−8) μm, each bordered by a thick ring and appearing round in surface view of cell; stem leaves without fibrils or fibrils weak 12. S. warnstorfii Pores larger, (5−)8–13 μm, not normally with thick rings, mostly flattened against margins of cells and appearing semicircular in surface view; fibrils of stem leaves usually conspicuous, occasionally weak or absent 13. S. capillifolium

Section Acutifolia

61

8 S. fimbriatum Wilson in J. D. Hook. & Wilson, Fl. Antarct., 1846 (Fig. 7) Autoicous. Shoots to 20 cm long, green, with large terminal buds, forming extensive ‘lawns’ or discrete tussocks. Stems 0.4–0.9 mm diameter; cortex 2–3 layers, pores present in 40–100% of cells on outer surface, 1(−2) per cell, round; cylinder green. Branches 3–4(−5) per fascicle, 2(−3) divergent, 1–2 pendent. Stem leaves 0.8–1.3 × 0.8–1.2 mm, spathulate, erect and appressed to stem; margin plane, fimbriate round most of upper leaf; border absent, or else 2–4 cells wide, ceasing below mid-leaf; patches of narrow cells at basal angles not pigmented, occupying 30–60% of leaf base; hyalocysts lacking fibrils and pores, extensively resorbed on both surfaces; upper cells 20–90% septate, grossly distorted in consequence of leaf margin having grown more than middle. Branch leaves 0.8–2.0 × 0.4–1.2 mm, ovate, not 5-ranked; border 1–3 cells wide; chlorocysts in section narrowly trapezoid, reaching both surfaces, with the greater exposure on the adaxial face; abaxial pores 10–20 μm, 5–13 per cell, near leaf base larger, often coalescing into extensive membrane gaps; adaxial pores 11–16 μm, 2–5 per cell, or sometimes absent in mid-leaf though always present near apex. Antheridial leaves green or yellowish-brown. Perichaetial leaves ± rectangular; border intact to apex; hyalocysts intact on both surfaces, lacking fibrils and pores. Spores 25–28 μm. Capsules common, summer.

Fig. 7 Sphagnum fimbriatum: 1, stem leaf (hatching indicates extent of narrow cells); 2, divergent branch leaves; 3, stem leaf cells 2/3 from base, abaxial side; 4, 5, cells at middle of divergent branch leaf, adaxial and abaxial side; 6, divergent branch leaf section. Leaves ×27, cells ×280.

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1 Sphagnaceae

n = 19, 19 + 4 m, 38 + 4 m∗ . Among Betula and Molinia in damp woodland, or on moors, banks, streamsides and degenerating bogs. 0–350 m. Frequent to common throughout the British Isles. 103, H24. GB664 + 52∗ , IR36 + 8∗ . Circumpolar Wideboreale. Arctic and cool temperate regions of the world in both hemispheres. Readily identified in the field by pulling off the top of the capitulum. The spathulate stem leaves appear as a conspicuous ‘ruff’ at the top of the decapitated stems. The large terminal buds are also a useful field character.

9 S. girgensohnii Russow, Arch. Naturk. Liv- Ehst- Kurlands, Ser. 2, 1865 (Fig. 8) Dioicous. Shoots to 20 cm long, green or faintly brownish, with medium-sized terminal buds, forming loose tussocks or ‘lawns’. Stems 0.5–0.8 mm diameter; cortex 2–3(−4) layers, pores present in 60–100% of cells on outer surface, 1(−2) per cell, round or transversely elliptical; cylinder green or pale brown. Branches 3–4(−5) per fascicle, 2(−3) divergent, 1–2 pendent. Stem leaves 0.8–1.3 × 0.6–0.9 mm, lingulate, erect and appressed to stem; apices plane, truncate and fimbriate or sometimes entire and rounded; border 2–5 cells wide, intact to near apex; patches

Fig. 8 Sphagnum girgensohnii: 1, stem leaves (hatching indicates extent of narrow cells); 2, divergent branch leaves; 3, stem cortex, surface view; 4, stem leaf cells 2/3 from base, abaxial side; 5, 6, cells at middle of divergent branch leaf, adaxial and abaxial side; 7, divergent branch leaf section. Leaves ×27, cells ×280.

Section Acutifolia

63

of narrow cells at basal angles usually with brown pigment, occupying 40–70% of leaf base; hyalocysts lacking fibrils and pores, equally and extensively resorbed on both surfaces; upper cells not, or hardly septate, some usually distorted by margin of leaf having grown more than middle. Branch leaves 1.1–1.6 × 0.5– 0.8 mm, ovate, not 5-ranked; margins strongly inrolled above so that the apex forms a snout which is slightly but distinctly bent backwards; border 1–2 cells wide; chlorocysts in section narrowly trapezoid, reaching both surfaces with the greater exposure on adaxial face; abaxial pores 8–16 μm, 4–15 per cell; adaxial pores 10– 15 μm, 3–5 per cell, or sometimes absent in mid-leaf though always present near apex. Antheridial leaves yellowish-brown. Perichaetial leaves oblong; border intact; hyalocysts intact on both surfaces, lacking fibrils and pores. Spores 22–25 μm. Capsules rare, summer. n = 19 + 4 m. On ditch sides, damp grassy banks and in mesotrophic marshes. 0–1000 m. Frequent to common in Wales, N. England and Scotland; rare in Ireland and southern England. 85, H9. GB373 + 31∗ , IR8 + 6∗ . Circumpolar Boreo-arctic Montane. Circumpolar, mainly boreal. Distinguished from S. fimbriatum in the field by the stem leaves widest at the base and fimbriate only at the apex, and by the often conspicuous brown pigmentation at their basal angles. The branches are stiffer and more rigid, and the snout-like apex of the branch leaves is usually more pronounced. S. girgensohnii can also resemble both S. teres and S. russowii (q.v. for differences), but the stem leaves are normally more torn than in either of those species.

10 S. russowii Warnst., Hedwigia, 1886 ¨ S. girgensohnii var. robustum (Russow) Dixon, S. robustum Roll

(Fig. 9)

Dioicous. Shoots to 20 cm long, variously crimson, variegated crimson and green, or green flecked with pink, rarely without any trace of red pigment, lacking enlarged terminal buds, forming loose tussocks. Stems 0.5–0.8 mm diameter; cortex 2–4 layers, pores present in 5–50(−100)% of cells on outer surface, 1 per cell, round, transversely elliptical or semicircular; cylinder green or red. Branches 3–4 per fascicle, 2 divergent, 1–2 pendent. Stem leaves erect and appressed to stem, 1.1–1.4 × 0.6–0.9 mm, lingulate; apex plane, usually rounded and ± entire, occasionally truncate and fimbriate because of resorption; border 3–5 cells wide, intact; patches of narrow cells at basal angles usually with red pigment, occupying 40–70% of leaf base; hyalocysts in upper leaf 0–50% septate, usually with obscure fibrils; abaxial surface ± intact, mostly with small longitudinal folds (membrane pleats); adaxial surface extensively resorbed and lacking; abaxial pores absent, or sometimes 1 per cell, 10–15 μm. Branch leaves 1.1–1.8 × 0.5–0.9 mm, ovate, varying from strongly 5-ranked to not at all 5-ranked, apices variable, sometimes appressed to branch, in others snout-like and slightly recurved when dry; border 1–3 cells wide; chlorocysts in section ± triangular, reaching both surfaces, broadly exposed on adaxial face; abaxial pores 9–18 μm, 7–13 per cell; adaxial pores often absent in mid-leaf, when present to 4 per cell, 8–16 μm (there are usually some

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Fig. 9 Sphagnum russowii: 1, stem leaves (hatching indicates extent of narrow cells); 2, divergent branch leaves; 3, stem cortex, surface view; 4, stem leaf cells 2/3 from base, abaxial side; 5, cells at middle of divergent branch leaf, abaxial side; 6, divergent branch leaf section. Leaves ×27, cells ×280.

adaxial pores near leaf apex). Antheridial leaves bright crimson, conspicuous. Perichaetial leaves oblong, obtuse; border intact to apex; hyalocysts intact on both surfaces, lacking fibrils and pores. Spores 24–27 μm. Capsules rare, summer. n = 38 + 8 m, 42. In marshes and on wet rocky ground, sometimes also on well drained banks with S. quinquefarium. 0–1200 m. Frequent to common from Wales northwards, especially at higher altitudes; rare in Ireland and southern England. 52, H13. GB217 + 24∗ , IR13 + 6∗ . Circumpolar Boreo-arctic Montane. Circumpolar, mainly boreal. Often hard to distinguish from S. capillifolium in the field, though normally more robust and with relatively broader branch leaves. Microscopically, S. russowii is distinguished by pores in the stem cortex, membrane pleats in the stem leaves and more numerous pores in the branch leaves. Green forms are occasionally hard to separate from S. girgensohnii. Usually they are distinct in the weakly fibrillose stem leaves. When stained, the different pattern of abaxial and adaxial resorption provides a definite structural difference.

Section Acutifolia

65

An allied species, S. rubiginosum Flatberg, is frequent in central Norway and might well occur in Scotland. It is autoicous and reddish, with stem leaves resembling those of S. girgensohnii; most fascicles have 3 divergent branches.

11 S. quinquefarium (Lindb. ex Braithw.) Warnst., Hedwigia, 1886 S. acutifolium var. quinquefarium Lindb. ex Braithw.

(Fig. 10)

Autoicous. Shoots to 20 cm long, green or pink, forming loose tussocks. Stems 0.4– 0.8 mm diameter; cortex 2–3 layers; pores present on outer surface, 1 per cell in 10–30% of cells, semicircular or occasionally round; cylinder green, or in plants whose leaves are pink, sometimes with a few red flecks. Branches (3−)4–5(−6) per fascicle, 2–3 divergent, 1–2(3) pendent. Stem leaves erect and appressed to stem, 0.9–1.4 × 0.6–0.9 mm, triangular or triangular-lingulate; apex rounded or acute, plane or somewhat inrolled; border 3–7 cells wide, entire; patches of narrow

Fig. 10 Sphagnum quinquefarium: 1, moist fascicle (×3); 2, stem leaves (hatching indicates extent of narrow cells); 3, divergent branch leaves; 4, stem leaf cells 2/3 from base, abaxial side; 5, cells at middle of divergent branch leaf, abaxial side; 6, divergent branch leaf section. Leaves ×27, cells ×280.

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cells at basal angles occupying 20–70% of leaf base; hyalocysts in upper leaf 30– 100% septate, weakly fibrillose or with fibrils absent; abaxial surface intact; adaxial surface extensively resorbed and lacking; abaxial pores normally absent, occasionally to 2 per cell, 15–25 μm. Branch leaves 0.8–1.6 × 0.4–0.6 mm, ovate or narrowly ovate, often strongly 5-ranked; chlorocysts in section triangular, broadly exposed on adaxial face; abaxial pores 11–22 μm, 4–7 per cell; adaxial pores absent. Antheridial leaves conspicuous, crimson or bright pink. Perichaetial leaves ovate; border intact; hyalocysts intact on both surfaces, lacking fibrils and pores. Spores 22–25 μm. Capsules occasional, summer or autumn. n = 19 + 2 m. On well drained sheltered banks and in steeply sloping acid woodland, avoiding waterlogged ground. 0–550 m. Frequent to common in the north and west, absent from central Ireland and from the Midlands and south-east of England. 58, H19. GB314 + 23∗ , IR38 + 8∗ . Suboceanic Boreal-montane. C. and W. Europe, chiefly in mountains and southern parts of the boreal zone, Transcaucasia, Japan, eastern and western N. America. Can be confused with S. capillifolium and S. subnitens. For differences see key. In the field, green forms can be confused with S. recurvum agg. (species 30–32). The erect stem leaves are a good macroscopic character separating it from members of Section Cuspidata. All fruiting plants examined were autoicous, but non-fruiting material is often apparently male.

12 S. warnstorfii Russow, Sitzungsber. Dorpater Naturf.-Ges., 1887 S. acutifolium var. gracile Russow, S. warnstorfianum Du Rietz

(Fig. 11)

Dioicous. Shoots to 15 cm long, variously crimson, rose-pink or green flecked with pink, forming loose carpets. Stems 0.4–0.5 mm diameter; cortex 2–3 layers, lacking pores on outer surface; cylinder red or green. Branches 3–4 per fascicle, 2 divergent, 1–2 pendent. Stem leaves erect and appressed to stem, 0.9– 1.3 × 0.5–0.8 mm, lingulate or triangular-lingulate; apices plane and rounded; border 3–7 cells wide, entire; patches of narrow cells at basal angles occupying 50–70% of leaf base; hyalocysts in upper leaf 30–100% septate, without fibrils or sometimes weakly fibrillose; abaxial surface intact; adaxial surface extensively resorbed and lacking; pores absent. Branch leaves 0.6–1.4 × 0.3–0.7 mm, ovate or narrowly ovate, usually strongly 5-ranked; border 1–4 cells wide; chlorocysts in section triangular, reaching both surfaces, broadly exposed on adaxial face; abaxial pores in mid-leaf 8–16 μm, 3–6 per cell, near leaf apex 2–6(−8) μm, (1−)2–6 per cell, thick-ringed, round, sometimes dimorphic with the pore at distal angle of cell then 6–8 μm when the lateral ones are 2–5 μm; adaxial pores absent in mid-leaf, above variably present or absent, 2–5 μm, to 4 per cell. Antheridial leaves conspicuous, crimson or bright pink. Perichaetial leaves as in S. capillifolium. Capsules unknown in Britain or Ireland. n = 19 + m. In base-rich flushes, frequent in upland areas with sufficiently base-rich water. 0–950 m but mainly above 400 m, descending to sea level in the west. N. Wales, N. England and

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67

Fig. 11 1–5, Sphagnum fuscum: 1, stem leaves (hatching indicates extent of narrow cells); 2, divergent branch leaves; 3, stem leaf cells 2/3 from base, abaxial side; 4, cells at middle of divergent branch leaf, abaxial side; 5, divergent branch leaf section. 6–12, S. warnstorfii: 6, stem leaves (hatching indicates extent of narrow cells); 7, divergent branch leaves; 8, divergent branch leaf cells near apex, abaxial side; 9, divergent branch leaf section; 10, stem leaf cells 2/3 from base, adaxial side; 11, cells at middle of divergent branch leaf, abaxial side. Leaves ×27, cells ×280.

Scotland; rare in Ireland. 31, H3. GB148 + 19∗ , IR2 + 2 m∗ . Circumpolar Boreo-arctic Montane. Circumpolar, arctic and boreal. Closely resembling S. capillifolium, both anatomically and in the field. It often grows with S. contortum and S. teres, and may be easier to recognise because of these associates than by its appearance. The branch leaves of S. warnstorfii are usually more markedly 5-ranked with narrower apices than those of S. capillifolium, but these characters are not constant and, occasionally intermediate plants can be found.

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13 S. capillifolium (Ehrh.) Hedw., Fund. Musc., 1782 Autoicous or dioicous. Shoots to 15 cm long, variously crimson, rose pink or green flecked with pink, forming hummocks, tussocks or loose carpets. Stems 0.4–0.6 mm diameter; cortex 2–4 layers, lacking pores on outer surface; cylinder red or green. Branches 3–4(−5) per fascicle, 2(−3) divergent, 1–2 pendent. Stem leaves erect and appressed to stem, or in compact forms sometimes spreading, 0.9– 1.4 × 0.5–0.9 mm, widest at base, lingulate or triangular-lingulate, rarely triangular; apices varying from plane and rounded to acute and somewhat inrolled; border 3–8 cells wide, entire; patches of narrow cells at basal angles occupying 20–70% of leaf base; hyalocysts in upper leaf 30–100% septate, a few often divided more than once, weakly or strongly fibrillose; abaxial surface intact; adaxial surface extensively resorbed and lacking; pores absent or sometimes a few ill-defined abaxial pores present. Branch leaves 0.8–1.4 × 0.4–0.6 mm, ovate or narrowly ovate, 5-ranked or not; chlorocysts in section triangular, broadly exposed on adaxial face; abaxial pores in mid-leaf 8–25 μm, 4–7(−9) per cell, near leaf apex 5–13 (−16) μm, 3–8 per cell, not normally thick-ringed, mostly flattened against commissures except at upper cell angles; adaxial pores absent or very few. Antheridial leaves bright crimson, conspicuous. Perichaetial leaves ovate; border intact; hyalocysts intact on both surfaces, lacking fibrils and pores. Spores 24–27 μm. Plants forming often dense tussocks; individual shoots with capitula rounded in outline; stem leaves usually more than 1.2 mm long ssp. capillifolium Habit variable, either in tussocks or forming loose carpets; individual shoots with flat-topped capitula; stem leaves usually less than 1.2 mm long ssp. rubellum Ssp. capillifolium (Fig. 12) S. acutifolium Ehrh. ex Schrad., S. capillaceum (Weiss) Schrank, S. nemoreum auct. non Scop. Autoicous or possibly also dioicous. Forming tussocks and hummocks. Capitula rounded in outline. Pendent branches appressed to stem and ± concealing it. Stem leaves lingulate or triangular-lingulate, 1.1–1.4 mm long, fibrillose in upper half, patches of narrow cells taking up 20–40% of width of leaf. Branch leaves imbricate, not or only slightly 5-ranked. Capsules frequent, summer. n = 19 + 2 m∗ , 19 + 4 m. On moors and blanket bogs. Widespread in upland Britain, generally much less common than ssp. rubellum; its distribution in Britain and Ireland is poorly known, Denbigh, Derby, Mid-West Yorkshire, S. Northumberland, Cumberland. 5. Circumpolar Boreo-temperate. Circumboreal. Ssp. rubellum (Wilson) M. O. Hill in Blockeel & Long, Check-List Cens. Cat. Brit. Irish Bryoph., 1998 (Fig. 12) S. rubellum Wilson, S. capillifolium var. tenellum (Schimp.) Crum Dioicous. Forming tussocks, hummocks or loose carpets. Capitula flattish at top. Pendent branches appressed to stem or not. Stem leaves lingulate, rounded at apex, 0.9–1.2 mm long, weakly fibrillose above, patches of narrow cells taking up

Section Acutifolia

69

Fig. 12 1, Sphagnum capillifolium ssp. capillifolium: 1, capitulum (×3). 2–11, S. capillifolium ssp. rubellum: 2, capitulum (×3); 3, moist fascicle (×3); 4 stem leaves (hatching indicates extent of narrow cells); 5, divergent branch leaves; 6, 7, stem leaf cells 2 /3 from base from different plants, adaxial side; 8, divergent branch leaf cells near apex, adaxial side; 9, cells at middle of divergent branch leaf, abaxial side; 10, stem section; 11, divergent branch leaf section. Leaves ×27, cells ×280.

35–70% of width of leaf. Branch leaves variously imbricate or loosely packed, often markedly 5-ranked. Capsules rare, summer. n = 19, 19 + 2 m∗ , 19 + 4 m. In bogs, marshes, moors and open woodland, avoiding localities that are either very wet or heavily shaded. 0–1040 m. Abundant in the north and west, frequent on bogs in the south and east. 104, H38. GB1018 + 74∗ , IR253 + 15∗ . Circumpolar Boreo-temperate. Circumboreal. Some authors recognise at least four microspecies within S. capillifolium in Britain and Ireland, but the pattern of variation is complex and cannot be summarised tidily in this

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way. The two subspecies are known to intergrade, but are distinguished by numerous correlated characters including their enzyme complements. The habit of ssp. capillifolium, with rounded capitula, in tussocks that are often dense, is the most reliable mark of distinction from ssp. rubellum. Ssp. capillifolium is on average more robust but there is wide overlap in size. Features of the stem leaves can be misleading, because plants that are undoubtedly ssp. rubellum sometimes produce relatively long, fibrillose stem leaves. Ssp. capillifolium is reported to be sometimes dioicous in other parts of its range. British plants with capsules are apparently all autoicous, but many non-fruiting plants could possibly be dioicous.

14 S. fuscum (Schimp.) H. Klinggr., Phys.-¨ok. Ges. K¨onigsb., 1872 S. acutifolium var. fuscum Schimp.

(Fig. 11)

Dioicous. Shoots to 15 cm long, brown, forming hummocks or occasionally carpets. Stems 0.3–0.5 mm diameter; cortex 3–4 layers, lacking pores on outer surface; cylinder dark brown. Branches 3–4 per fascicle, 2 divergent, 1–2 pendent. Stem leaves erect and appressed to stem, 0.8–1.3 × 0.4–0.7 mm, lingulate or lingulatespathulate, either widest at base or somewhat narrowed in mid-leaf and widest near apex; apices plane and rounded; border 5–9 cells wide, entire; patches of narrow cells at basal angles occupying 40–80% of leaf base; hyalocysts in upper leaf (40−)80–100% septate, sometimes divided more than once, lacking fibrils; abaxial surface intact; adaxial surface extensively resorbed and lacking; pores absent. Branch leaves 0.9–1.3 × 0.3–0.5 mm, ovate or narrowly ovate, not 5-ranked; border 1–2 cells wide; chlorocysts in section triangular, reaching both surfaces, broadly exposed on adaxial face; abaxial pores 12–30 μm, 3–7 per cell; adaxial pores 10– 20 μm, 0(−1) per cell. Antheridial leaves brown, somewhat darker than other leaves. Perichaetial leaves ovate; border intact; hyalocysts intact on both surfaces, lacking fibrils and pores. Spores 24–27 μm. Capsules rare, summer. n = 19 + 2 m. In most of Britain and Ireland a rather rare plant of raised bogs; more frequent in N. E. England and E. Scotland, occurring in flushes and on blanket bogs. 0–1000 m but mainly above 400 m. 36, H18. GB184 + 12∗ , IR48 + 7∗ . Circumpolar Boreo-arctic Montane. Circumpolar, mainly in the boreal zone and tundra. Easily recognised in the field, resembling S. capillifolium in habit, but brown. It is sometimes confused with brown forms of S. subnitens, but is at once distinct in the shape of the stem leaves. In most of the characters given above it comes close to S. capillifolium, especially ssp. rubellum, but S. fuscum has markedly bigger pores near the base of the branch leaves (15– 40 μm, as opposed to 8–20(−25) μm), and there is a greater contrast between the size of the cells in the leaf base and those at the apex than in S. capillifolium. In S. fuscum the abaxial pores near the leaf apex are sometimes small, resembling those of S. warnstorfii.

15 S. subnitens Russow & Warnst. in Warnst., Abh. Bot. Ver. Prov. Brandenburg 1888 ¨ S. acutifolium var. subnitens (Russow & Warnst.) Dixon, S. plumulosum Roll Autoicous. Shoots to 20 cm long, variously green, brown, red or pink, with a metallic sheen when dry, forming loose or compact tussocks or greenish ‘lawns’.

Section Acutifolia

71

Stems 0.4–0.7 mm diameter; cortex (2−)3–4 layers lacking pores on outer surface, cylinder usually coppery-brown, sometimes red or green. Branches in fascicles of 3(−4), 2 divergent 1(−2) pendent. Stem leaves erect and appressed to stem, or in compact forms sometimes spreading, 1.1–1.7 × 0.6–1.0 mm, triangular; apex acute, often somewhat cuspidate because of inrolled margins; border 3–7 cells wide, entire; patches of narrow cells at basal angles occupying 20–60% of leaf base; hyalocysts in upper leaf (50−)80–100% septate, often divided more than once, without fibrils or rarely weakly fibrillose; abaxial surface intact; adaxial surface extensively resorbed and lacking; pores absent. Branch leaves (0.9−)1.2– 2.7 × 0.5–1.3 mm, ovate or narrowly ovate, not 5-ranked, or in small plants rarely with weak 5-ranking; chlorocysts in section triangular, broadly exposed on adaxial face; abaxial pores commonly ± invisible without folding leaf because of bulging hyalocysts, 16–30 μm, 4–10 per cell; adaxial pores absent. Antheridial leaves not markedly different in pigmentation from others. Perichaetial leaves ovate; border intact; hyalocysts intact on both surfaces, lacking fibrils and pores. Spores 26– 30 μm. Capsules common, summer. Suboceanic Boreo-temperate. Colour various, plants developing red pigment when well illuminated; stem leaves acute with inrolled margins var. subnitens Plants brownish, lacking red pigment; stem leaves subacute to acute, with weakly inrolled margins var. ferrugineum Var. subnitens (Fig. 13) Colour various, plants developing red pigment when well illuminated; stem leaves acute with inrolled margins. This is the common form in Britain and Ireland. On moors, heaths, rocky banks and in woods, avoiding flat acid bogs. 0–800 m. Abundant in the north and west, common in woods and on heaths in the Midlands and south. 108, H39, C. GB1031 + 73∗ , IR254 + 18∗ . Circumpolar, extending south to the Azores; New Zealand (probably introduced). Var. ferrugineum (Flatberg) M. O. Hill in Blockeel & Long, Check-List Cens. Cat. Brit. Irish Bryoph., 1998 ¨ S. subnitens ssp. ferrugineum Flatberg, S. subfulvum auct. hib. non Sjors Colour brownish, plants lacking red pigment; stem leaves subacute to acute, with weakly inrolled margins. Very rare, Stirling, W. Galway, Roscommon, W. Mayo, Antrim. 1, H4. GB1, 1R4. Norway, west Greenland, northern Canada and Alaska, in the boreal zone and low Arctic. The name subnitens refers to the pronounced lustre that the species often has when dry. This can be a useful diagnostic character in the herbarium. Green forms of ditches and damp woods can resemble S. inundatum or S. fallax. S. inundatum has rounded stem leaves, and in S. fallax the stem leaves are hanging. For differences from S. quinquefarium see key. S. capillifolium is normally smaller, with a pronounced concentration of red pigment in the central part of the capitulum. In S. subnitens the centre of the capitulum is seldom redder

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Fig. 13 Sphagnum subnitens var. subnitens: 1, stem leaves (hatching indicates extent of narrow cells); 2, divergent branch leaves; 3, stem leaf cells 2/3 from base, abaxial side; 4, cells at middle of divergent branch leaf, abaxial side; 5, divergent branch leaf section. Leaves ×27, cells ×280. than the surrounding branches, and is often paler. Moreover, S. subnitens often contains some brown pigment, making the red rather dingy. Var. ferrugineum appears to be little more than a brownish morph of typical Sphagnum subnitens. The shape of the stem leaves is not decisive; leaves of similar shape can be found in undoubted var. subnitens. When an Irish specimen of var. ferrugineum was first found, it ¨ This view was challenged by K. I. Flatberg (Lindbergia, was thought to be S. subfulvum Sjors. 11, 38–54, 1985) who demonstrated a complex pattern of variation in the S. subnitens–S. subfulvum group, with the characters that supposedly define S. subfulvum not being as well correlated as had been supposed.

16 S. skyense Flatberg, J. Bryol., 1988 (Fig. 14) Sexuality unknown. Robust, in habit resembling a large form of S. subnitens. Stems pale red, cortex 3–4 cells wide, some cells on outer surface with one ± circular pore. Branches in fascicles of 3–4, 2 divergent. Stem leaves broadly triangular or triangular-lingulate, 1.4–1.8 × 1.0–1.5 mm, acute to subacute, margins ± plane or somewhat inrolled above; patches of narrow cells at basal angles occupying 20– 60% of leaf base; hyalocysts in upper part of leaf either not septate or divided into two, rarely a few divided into 3 or 4. Branch leaves ovate, not or scarcely 5-ranked, 1.5–1.8 × 0.5–0.7 mm. Wet heath. Lowland. Skye. 1. GB1. Endemic (Hyperoceanic Temperate).

Section Acutifolia

73

Fig. 14 Sphagnum skyense: 1, moist fascicle (×4); 2, stem leaves; 3, divergent branch leaves; 4, divergent branch leaf margin near apex, abaxial side; 5, 6, cells at middle of divergent branch leaf, adaxial and abaxial side; 7, divergent branch leaf section. Leaves ×27, cells ×280. A little known plant, found in 1987 in a single locality and not re-found in spite of searching. The best field character to distinguish it from S. subnitens is that many of the fascicles have 2 pendent branches whilst in S. subnitens almost all the fascicles have 1 pendent branch. Microscopically the areolation of both stem and branch leaves is laxer than is usual in S. subnitens. K. I. Flatberg (J. Bryol. 15, 101–7, 1988) suggested that S. skyense might be a hybrid between S. quinquefarium and S. subnitens. He also pointed out the similarity to S. junghuhnianum Dozy & Molk., a mainly Asian species which occurs rarely in the Pacific Northwest of North America. Daniels & Eddy (1990) state that S. skyense and S. junghuhnianum are probably conspecific.

17 S. molle Sull., Musci Allegh., 1845 (Fig. 15) Autoicous. Shoots to 10 cm long, whitish or pink, forming low tussocks. Stems 0.2– 0.5 mm diameter; cortex (1−)2–3 layers, with pores in 10–50% of cells on outer surface; cylinder green or pale brown. Branches 2–3(−4) per fascicle, mostly squeezed together in the tufts and pointing upwards, sometimes 1(−2) pendent; retort cells in groups of (1−)2–5 (mostly solitary in other Section Acutifolia). Stem leaves spreading or erect, 1.5–2.8 × 0.4–1.5 mm, rhomboid, oblong

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Fig. 15 Sphagnum molle: 1, stem leaves; 2, divergent branch leaves; 3, stem leaf cells 2/3 from base, abaxial side; 4, cells at middle of divergent branch leaf, abaxial side; 5, divergent branch leaf margin near apex, abaxial side; 6, divergent branch leaf section. Leaves ×27, cells ×280.

or lingulate; apices acute, plane or with ± inrolled margins; border (1−)2–3 cells wide, denticulate above because of resorption of cell walls along margins; patches of narrow cells at basal angles absent; hyalocysts fibrillose in a zone 40–100% of leaf, 0–40% septate in mid-leaf; abaxial pores ringed, 13–22 μm, 0–8 per cell; adaxial pores large, 15–30 μm, unringed, 0–3 per cell, or sometimes replaced by larger membrane gaps. Branch leaves 1.4–2.3 × 0.5–1.2 mm, ovate, not 5-ranked; border 1–2 cells wide, denticulate at least in upper half because of resorption of outer surface of cells along margin (border is intact in branch leaves in European Section Acutifolia); chlorocysts in section triangular, broadly exposed on adaxial surface, not, or hardly, exposed on abaxial surface; hyalocysts strongly protuberant on abaxial surface; abaxial pores ± invisible without folding leaf because of highly protuberant hyalocysts, 14–22 μm, 6–12 per cell; adaxial pores absent. Antheridial leaves greenish, not different in pigmentation from others. Perichaetial leaves ovate, acuminate; border 3–4 cells wide; hyalocysts lacking fibrils and pores, or a few cells with fibrils and abaxial pores. Spores 28– 32 μm. Capsules common, summer. n = 19, 19 + 2 m, 19 + 4 m. On damp ground

Section Rigida

75

by streams and on heaths. 0–350 m. Throughout the British Isles but rare in most districts except western Scotland. 59, H17. GB129 + 20∗ , IR33 + 2∗ . Suboceanic Temperate. Western Europe eastwards to the Baltic and C. Europe; eastern N. America. In habit resembling S. compactum, but immediately distinct in the large stem leaves, pale stem and traces of pink colouring. Lax forms may resemble S. subnitens, but the large stem leaves and lack of well defined pendent branches will usually separate S. molle. In S. molle the tufts are usually interwoven with ± unbranched julaceous stems, whose cortex has well marked retort cells. This is one aspect of a general lack of differentiation between stems and branches which is manifested also in the leaves.

Section 4 Rigida (Lindb.) Schlieph. ex Limpr., Laubm. Deutschl., 1885 Plants medium-sized. Stems usually 0.4–0.8 mm diameter; cortex 2–3 layers, hyaline, 30–100 μm wide, cell walls without spiral fibrils, those on outer surface each with one ± semicircular pore at upper end; diameter of cortical cells measured at right-angles to radius, 20–70 μm; cylinder strongly differentiated from cortex. Branches in fascicles of 2–7, the 1–3 divergent branches very sharply differentiated from the 1–5 pendent branches; cells of branch cortex each with an apical pore, not dimorphic, lacking spiral fibrils. Stem leaves hanging, usually 0.3–0.7 × 0.4– 0.7 mm, triangular or trapezoid, with a border of 3–8 narrow cells; border intact below, above varying from ± entire to extensively resorbed and tattered; patches of narrow cells at basal angles absent; hyalocysts not, or a few, septate; abaxial surface with or without fibrils; adaxial surface almost completely resorbed, and either lacking or very thin with large pores. Branch leaves varying from oblong and ± cucullate to ovate-acuminate with a squarrose acumen, usually 1.7– 3.0 × 0.8–1.8 mm; apex rounded or broadly truncate; border 1(−3) cells wide, usually completely resorbed and represented only by a resorption furrow (margin appears denticulate owing to projection of transverse cell walls which persist after resorption of border); chlorocysts lens-shaped or elliptical in section, either enclosed by hyalocysts or slightly exposed on abaxial surface; hyalocysts near leaf apex longer than wide (a few at extreme apex ± as wide as long), their abaxial surface sometimes with a pore at distal angle but not lacunose; abaxial pores in mid-leaf 5–25 μm, 0–4(−8) per cell, positioned at cell angles or more generally along commissures (a few large pores are sometimes centrally placed, but these are never the majority); adaxial pores absent in mid-leaf, near apex present or absent, either in triplets at corners of 3 adjacent hyalocysts, or distributed more generally along commissures (in mid-leaf the annular fibrils of adaxial pores may be present but without any marked membrane thinning within them). Antheridia on pendent branches. Perichaetial leaves resembling branch leaves, ovate, acute; border intact, 2–6 cells wide, distinct to apex; hyalocysts not extensively resorbed on either surface, fibrillose and porose in at least the upper half of leaf, often throughout; pores various, commonly present on both surfaces, positioned at cell angles or distributed more generally along commissures.

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Key to Sphagnum Section Rigida Stems greenish or pale brown; branch leaves squarrose, chlorocysts just reaching abaxial surface; abaxial pores in upper half of leaf 1(−6) per cell, 10–25 μm, mostly positioned at distal angles of hyalocysts 18. S. strictum Stems dark brown or black, rarely pale; branch leaves usually ± appressed, occasionally squarrose, chlorocysts completely enclosed on both surfaces; abaxial pores in upper half of leaf few to numerous, (1−)3–10(−12) per cell, 5–12(−16) μm, distributed along commissures and not concentrated on distal angles of hyalocysts 19. S. compactum 18 S. strictum Sull., Musci Allegh., 1845 (Fig. 16) Autoicous. Shoots to 15 cm long, green or brownish, forming small tussocks. Stems 0.5–0.8 mm diameter; cortex 2–3 layers; pores on outer surface one per cell; cylinder green or pale brown. Branches 3–6 per fascicle, 2–3 divergent, 1–3 pendent. Stems leaves hanging, 0.5–0.7 × 0.5–0.6 mm, triangular, apices rounded and ± cucullate; border 4–8 cells wide, near apex denticulate but not fimbriate; patches of narrow cells at basal angles absent; hyalocysts not, or a few, septate, lacking fibrils; abaxial surface intact; adaxial surface ± completely resorbed and lacking. Branch leaves 1.7–2.7 × 0.8–1.5 mm, ovate, with squarrose acumens whose extreme apex is abruptly truncate; border 1 cell wide, denticulate because of resorption; chlorocysts just reaching abaxial surface of leaf, enclosed on adaxial surface, in section lens-shaped, measuring (15−)17–27 μm along long axis; interior walls of hyalocysts where they abut on chlorocysts obscurely papillose; abaxial pores in mid-leaf often absent, when present 10–25 μm, mostly one per cell at distal angle, sometimes more numerous, especially near leaf apex; adaxial pores normally absent in mid-leaf, near apex occurring in triplets, one at the corner of each of 3 adjacent hyalocysts. Antheridial leaves whitish, not contrasting with leaves on sterile pendent branches. Perichaetial leaves ovate, acute, fibrillose; border 3–5 cells wide; abaxial pores large, mostly 1 per cell at distal angle, or sometimes absent; adaxial pores also large, near leaf apex forming well defined triplets one at each corner of 3 adjacent hyalocysts. Spores 28–30 μm. Capsules frequent, summer. n = 19 + 2 m. On blanket bog and wet moorland, especially among Molinia. 0–550 m. N. Wales, Lake District, N. and W. Scotland, N. and W. Ireland; rare except in the hyperoceanic districts of Scotland and Ireland. 20, H9. GB126 + 9∗ , IR22 Hyperoceanic Temperate. Europe from western and southern Scandinavia south to Switzerland; eastern N. America; another subspecies is widespread in the tropics and southern Africa. With its squarrose branch leaves it has some resemblance to S. squarrosum, but differs in its small stem leaves. In the field it can be distinguished from squarrose-leaved forms of S. compactum by its pale stems and usually laxer habit. The difference in pore structure from S. compactum appears constant in British and Irish plants but does not hold in N. America.

Section Rigida

Fig. 16 1–6, Sphagnum strictum: 1, moist fascicle (×3); 2, divergent branch leaves; 3, stem leaves; 4, cells at middle of divergent branch leaf, abaxial side; 5 divergent branch leaf section; 6, stem section. 7–12, S. compactum: 7, moist fascicle (×3); 8, divergent branch leaves; 9, stem leaves; 10, cells at middle of divergent branch leaf, abaxial side; 11 divergent branch leaf section; 12, stem section. Leaves ×27, cells ×280.

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19 S. compactum Lam. & DC., Fl. Franc¸., 1805 S. rigidum (Nees & Hornsch.) Schimp.

(Fig. 16)

Autoicous. Shoots to 10 cm long, variously whitish green, yellowish or bright ochre, forming low, often dense tussocks. Stems 0.4–0.7 mm diameter; cortex 2–3 layers; pores on outer surface 1 per cell; cylinder dark brown or black, rarely pale. Branches 2–7 per fascicle, 1–2 divergent, 1–5 pendent. Stem leaves hanging, 0.3–0.7 × 0.4–0.7 mm, triangular or trapezoid, apices rounded, truncate or retuse; border 3–8 cells wide, intact in lower part of leaf, near apex variable, usually strongly resorbed and tattered; patches of narrow cells at basal angles absent; hyalocysts not, or slightly septate, with or without fibrils; abaxial surface intact; adaxial surface ± completely resorbed and lacking. Branch leaves 1.8–3.0 × 0.9– 1.8 mm, varying from oblong and ± cucullate to ovate with squarrose acumens, extreme apex rounded or truncate; border 1(−3) cells wide, denticulate because of resorption of outer surface of cells along margins; chlorocysts completely enclosed by hyalocysts, in section elliptical, measuring 11–16 μm along long axis; interior walls of hyalocysts smooth; abaxial pores in mid-leaf very variable, perforate or imperforate, 5–12(−16) μm, 0–4(−8) per cell, distributed along commissures, near leaf apex more numerous, to 12 per cell; adaxial pores absent in mid-leaf. (Numerous annular fibrils are often present along commissures on both surfaces, but the membrane within them is mostly not thinned.) Antheridial leaves white, not contrasting with those on sterile pendent branches. Perichaetial leaves ovate, acute; border 2–6 cells wide; hyalocysts fibrillose, with abundant, mostly imperforate small ringed commissural pores on both surfaces, or those on adaxial surface sometimes larger and less abundant. Spores 30–35 μm. Capsules frequent, summer. n = 19 + 2 m. On wet heaths, blanket bogs and among rocks, favouring moist but not wet ground, especially where there has been some disturbance such as burning. 0–1050 m. Frequent to common throughout the British Isles except in the Irish and English midlands. 93, H34. GB575 + 70∗ , IR102 + 12∗ . Circumpolar Boreo-temperate. Circumpolar in the boreal zone and low Arctic, and in mountains south to Macaronesia, Turkey and southern USA, Colombia, Hawaii. Usually easy to recognise in the field, the shoots being so densely crowded that the upper branches point upwards and the individual capitula are hard to discern. The habit may resemble Leucobryum glaucum. S. compactum can resemble compact forms of S. molle, S. palustre, S. papillosum or S. squarrosum, but differs in its minute hanging stem leaves. For field differences from S. strictum see under that species.

Section 5 Subsecunda (Lindb.) Schlieph. ex Schimp., Syn. Musc. Eur. (Ed. 2), 1876 Plants slender to robust. Stems usually 0.4–0.8 mm diameter; cortex 1–3 layers, hyaline, 15–60 μm wide, cell walls without fibrils, those on outer surface without pores or with a single indistinct pore at upper end; diameter of cortical cells measured at right angles to radius 15–50(−60) μm; cylinder strongly differentiated from cortex. Branches often curved, in fascicles of 1–6(−7), 1–3 divergent,

Section Subsecunda

79

0–4 pendent; branch cortex with clearly dimorphic cells, cell walls without spiral fibrils; retort cells with a moderate neck, in groups of (1−)2(−4). Stem leaves erect, spreading or hanging, usually 0.4–2.0 × 0.4–1.1 mm; border 3–6 cells wide, near apex entire or denticulate; patches of narrow cells at basal angles absent; hyalocysts septate or not, strongly or weakly fibrillose, not extensively resorbed on either surface, or rarely with extensive adaxial resorption; abaxial pores ringed, 2–8 μm, absent or to 40 per cell; adaxial pores ringed or not, 3–15 μm, absent or to 20 per cell. Branch leaves ovate or elliptical, sometimes concave and cucullate, usually 0.7–2.5 × 0.4–1.5 mm, with an intact border of 2–4 narrow cells; chlorocysts lens-shaped or barrel-shaped in cross-section, ± equally exposed on both surfaces, or slightly more exposed on abaxial surface; hyalocysts near apex longer than wide, their abaxial surface without a large pore at distal angle; abaxial pores in mid-leaf (1−)2–6 μm, (0−)12–40(−50) per cell, strongly ringed, positioned along commissures, usually with 2 corresponding to each fibril, one on each commissure; adaxial pores normally absent, when present similar to abaxial pores though often confined to cell angles. Antheridia on divergent branches. Perichaetial leaves triangular or oblong; border 2–3 cells wide, distinct almost to apex; hyalocysts fibrillose near leaf apex, not extensively resorbed on either surface; abaxial pores numerous, resembling those of branch leaves; adaxial pores few, similar.

Key to Sphagnum Section Subsecunda 1 Stem leaves triangular or lingulate, 0.4–1.3(−1.5) mm long, fibrillose for 40% or less of length of leaf, adaxial pores equally or more developed than abaxial pores (abaxial pores may be absent); pendent branches strongly or weakly differentiated from divergent branches; colour green or yellowish, not coppery-red 2 Stem leaves lingulate, oblong or elliptical, (1.0−)1.3–2.3 mm, fibrillose in upper 40% or more, abaxial pores numerous, adaxial pores usually much fewer, occasionally equally numerous; pendent branches weakly or not at all differentiated from divergent branches; colour green, yellowish or coppery-red 4 2 Stem cortex consisting of 2–3 layers of enlarged cells; cylinder green or pale brown; adaxial pores of stem leaves 3–6 μm, lying along commissures 23. S. contortum Stem cortex 1 layer; cylinder green, pale brown, or in well illuminated plants usually dark brown; adaxial pores of stem leaves 5–15 μm, some usually centrally placed 3 3 Slender plants (size similar to S. capillifolium); stem leaves 0.4–0.9 × 0.4–0.6 mm; upper cells fibrillose in a zone 0–25% of length of leaf; branch leaves 0.7–1.5 × 0.4–0.8 mm 20. S. subsecundum Medium-sized plants; stem leaves 0.9–1.3(−1.5) × 0.6–0.9 mm; upper cells fibrillose in a zone 20–40% of leaf length; branch leaves (1.0−)1.3–2.2 × 0.6–1.5 mm 21. S. inundatum

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4 Stem cortex uniformly 1 cell thick; stem leaves lingulate or oblong, often ± plane, 40–100% fibrillose; branches tumid or not, arising in fascicles of 3–5 22. S. denticulatum Stem cortex irregularly 1–2(−3) cells thick; stem leaves elliptical, markedly concave, 80–100% fibrillose; branches tumid, fascicles of 1–3(−4) 24. S. platyphyllum 20 S. subsecundum Nees in Sturm, Deutschl. Fl., Abt. II, Cryptog., 1819 (Fig. 17) Dioicous. Shoots to 15 cm long, normally yellow or ochre but green in shade and submerged forms, growing in loose carpets or as scattered plants. Stems 0.4– 0.7 mm diameter; cortex one layer, cells of outer surface with indistinct pores at upper end or pores absent; cylinder dark brown, or in shade forms green. Branches 4–6(−7) per fascicle, 2–3 divergent, 2–4 pendent; divergent branches clearly differentiated from pendent branches, often markedly curved. Stem leaves hanging, or a few sometimes spreading, 0.4–0.9 × 0.4–0.6 mm, triangular or triangularlingulate, apices plane or cucullate, rounded; border 3–6 cells wide, ± strongly fringed round apex; patches of narrow cells at basal angles absent; hyalocysts not septate; upper cells fibrillose in a zone 0–25% of length of leaf; abaxial pores absent; adaxial pores 5–14 μm, 0–10 per cell, unringed, centrally placed or lying along commissures. Branch leaves 0.7–1.5 × 0.4–0.8 mm, ovate, secund and pointing towards centre of curve of branch; border 2–3 cells wide; chlorocysts in section lens-shaped, reaching both surfaces or just enclosed on adaxial surface; abaxial pores 2–5 μm, (0−)20–40 per cell ringed, lying along commissures, adaxial pores absent or rarely 4–6 μm, to 6 per cell. Antheridial leaves bright yellow. Perichaetial leaves narrowly ovate, fibrillose and porose near apex. Spores 27–29 μm. Capsules rare. n = 19 + 2 m. In base-rich flushes and fens, favouring slightly more acid conditions than S. contortum. 0–740 m. Throughout Britain, frequent in some upland districts but mostly rather rare, rare in Ireland. 23, H5. GB50 + 7∗ , IR4. Circumpolar, mainly in the boreal zone. Usually easy to recognise in the field, with bright yellow or ochre colour, dark brown stems, curved branches, and slender habit resembling S. capillifolium. Depauperate S. inundatum can be mistaken for it, and sometimes produces stem leaves that are similar. Branch leaf size will usually distinguish these forms. Moreover, S. subsecundum is quite stable in its small size, but depauperate S. inundatum almost always betrays its true identity by producing some normal-sized stems and branch leaves in parts of the plant.

21 S. inundatum Russow, Arch. Nat. Dorpat II, 1894 (Fig. 17) S.auriculatum var. inundatum (Russow) M. O. Hill, S. bavaricum Warnst., S. subsecundum var. bavaricum (Warnst.) Åberg, S. subsecundum var. inundatum (Russow) C. E. O. Jensen Dioicous. Shoots to 20 cm long, green or yellow, forming ‘lawns’ or loose tufts. Stems 0.4–0.8 mm diameter; cortex 1 layer, cells of outer surface without

Section Subsecunda

81

Fig. 17 1–8, Sphagnum subsecundum: 1, moist fascicle (×3); 2, divergent branch leaves; 3, stem leaves (hatching indicates distribution of fibrils); 4, cells at middle of divergent branch leaf, abaxial side; 5, stem leaf cells 3/5 from base, adaxial side; 6, stem leaf margin near apex; 7 divergent branch leaf section; 8, stem section. 9–13, S. inundatum: 9, divergent branch leaves; 10 stem leaf (hatching indicates distribution of fibrils); 11, cells at middle of divergent branch leaf, abaxial side; 12, stem leaf cells 3/5 from base, adaxial side; 13, stem leaf margin near apex, abaxial side. Leaves ×27, cells ×280.

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pores; cylinder dark brown or black, or in shade forms green. Branches 4–6(−7) per fascicle, differentiated into 2–3 divergent, 2–4 pendent; divergent branches curved or not. Stem leaves spreading or hanging, 0.9–1.3(−1.5) × 0.6–0.9 mm, lingulate or triangular-lingulate, apex rounded; border 3–5 cells wide, ± fringed or toothed near apex; patches of narrow cells near basal angles absent; hyalocysts 0–50% septate, fibrillose in a zone 20–40% of length of leaf; abaxial pores near apex variously absent to numerous, 3–8(−11) μm; adaxial pores well developed, unringed, 5–12(−15) μm, centrally placed or positioned along commissures, some usually relatively large (8–12 μm). Branch leaves (1.0−)1.3– 2.2 × 0.6–1.5 mm, patent or imbricate; border 2–3 cells wide; chlorocysts in section barrel-shaped or lens-shaped, exposed on both surfaces or slightly enclosed on adaxial surface; abaxial pores 2–6 μm, (0−)20–40(−50) per cell, ringed, lying along commissures; adaxial pores absent or rarely 2–6 μm, to 6 per cell. Antheridial leaves yellow. Perichaetial leaves ovate or triangular, acute, fibrillose and porose above. Spores 31–34 μm. Capsules occasional, summer. n = 38 + 4 m∗ , c. 42. In marshes, heathy depressions, and wet woodland. 0–850 m. Frequent to common throughout the British Isles. 98, H30. European Boreotemperate. Cool-temperate zone of N. W. Europe, eastern N. America and eastern Asia. When growing in well illuminated conditions the dark stem is a useful field character separating it from unrelated species. The name inundatum is misleading: swollen submerged plants of S. subsecundum agg. are almost always S. denticulatum. S. inundatum is intermediate in most respects between S. subsecundum and S. denticulatum; notes on how to distinguish it are given under these species. There has been a debate as to whether S. inundatum ought to be treated as a subspecies of S. subsecundum or of S. denticulatum. Most European authors now treat it as a separate species, thereby avoiding the problem.

22 S. denticulatum Brid., Bryol. Univ., 1826 (Fig. 18) S. auriculatum Schimp., S. contortum auct. non Schultz, S. lescurii Sull., S. rufescens (Nees & Hornsch.) Limpr., S. subsecundum auct. angl. p.p. Dioicous. Shoots to 20 cm long, green, yellow or coppery red, forming loose carpets or tussocks. Stems 0.4–0.8 mm diameter; cortex 1 layer, cells of outer surface without pores; cylinder dark brown or black, or in shade and submergence forms green. Branches 3–4(−5) per fascicle, either not differentiated, or weakly differentiated into 2–3 divergent, 1–2(−3) pendent; divergent branches curved or not (when there are 5 branches in a fascicle one or two are often small and poorly developed). Stem leaves erect, spreading or hanging, (1.1−)1.3– 2.0(−2.7) × 0.6–1.0(−1.5) mm, lingulate or oblong, apex rounded; border 3–5 cells wide, ± fringed or toothed near apex; patches of narrow cells near basal angles absent; hyalocysts 0–100% septate, fibrillose in a zone 40–100% of length of leaf; abaxial pores near apex numerous, 3–8 μm, to 30 per cell; adaxial pores 0–20 per cell, 3–8(−12) μm, when present mostly lying along

Section Subsecunda

83

Fig. 18 Sphagnum denticulatum: 1, moist fascicle (×3); 2, divergent branch leaves; 3, stem leaf (hatching indicates distribution of fibrils); 4, cells at middle of divergent branch leaf, abaxial side; 5, stem leaf cells 3/5 from base, adaxial side; 6, stem leaf margin near apex, abaxial side; 7, divergent branch leaf section; 8, stem section. Leaves ×27, cells ×280.

commissures. Branch leaves 1.3–2.5(−3.5) × 0.8–1.5(−2.0) mm, imbricate or occasionally patent; border 2–3 cells wide; chlorocysts in section barrel-shaped or lens-shaped, exposed on both surfaces or slightly enclosed on adaxial surface; abaxial pores 3–6 μm, (0−)20–40(−50) per cell, ringed, lying along commissures; adaxial pores absent or rarely 3–5 μm, to 5 per cell. Antheridial leaves yellow (but not observed in reddish plants). Perichaetial leaves ovate or triangular, acute, fibrillose and porose above. Spores 30–33 μm. Capsules occasional, summer. n = 38 + 4∗ . In woods, moorland runnels and pools, tolerant of very acid water, sometimes completely submerged. 0–1100 m. Throughout the British Isles; very common in the north and west; frequent to common in the south and

84

1 Sphagnaceae

east. 106, H38. GB1093+80∗ , IR214+24∗ , C3. European Boreo-temperate. N. W. Europe, N. Africa, eastern Asia, western and eastern N. America, south to northern S. America. Variable both in habit and colour, with a strong phenotypic response to the position of the water-table. Coppery forms of flushed base-poor upland banks normally have curled branches resembling cattle horns, and can be recognised at a glance. Turgid plants submerged in pools have a superficial resemblance to S. palustre but differ in the narrow stems without a wide cortex layer. Green or yellowish forms of woods and marshes can closely resemble S. inundatum and may require microscopic examination. Even then, some plants may appear intermediate. Whether these are genetically intermediate is not known.

23 S. contortum Schultz, Prodr. Fl. Starg. Suppl., 1819 (Fig. 19) S. laricinum (Wilson) Spruce Dioicous. Shoots to 15 cm long, green, yellow or brownish, in loose carpets or occurring as scattered stems. Stems 0.4–0.7 mm diameter; cortex 2–3 layers, cells of outer surface mostly with a rather faint pore at upper end; cylinder green or pale brown. Branches 4–5(−7) per fascicle, 2–3 divergent, (1−)2–4 pendent; divergent branches clearly differentiated from pendent branches, often markedly curved. Stem leaves spreading or hanging, 0.7–1.3 × 0.5–1.0 mm, triangular or triangularlingulate, apex rounded or retuse; border 3–5 cells wide, partially resorbed and denticulate or fringed round apex; patches of narrow cells at basal angles absent; hyalocysts not septate; upper cells fibrillose in a zone 10–35% of length of leaf; abaxial pores near leaf apex 2–4 μm, 0–4(−6) per cell; adaxial pores 3–6 μm, 3–12 per cell, lying along commissures. Branch leaves 1.0–1.9 × 0.5–0.9 mm, ovate or narrowly ovate, often distinctly secund and pointing towards centre of curve of branch; border 2–4 cells wide; chlorocysts in section lens-shaped, reaching abaxial surface, just enclosed on adaxial surface; abaxial pores in mid-leaf very small, 1–3 μm, sometimes to 30 per cell, often ± indistinct or obsolete; adaxial pores absent. Antheridial leaves ochre with a slight pink tinge. Perichaetial leaves ovate, fibrillose and porose above. Spores 24–27 μm. Capsules unknown in Britain. Confined to base-rich habitats, mainly upland flushes, less often lowland fens. 0–800 m. Throughout the British Isles, frequent in the north and west, rare in the south and east. 57, H23. GB186 + 32∗ , IR20 + 9∗ . Boreal-montane. Circumpolar, mainly in the boreal zone. In the field the curved branches and normally ochre colour will suggest this species, S. subsecundum or S. inundatum. Well illuminated S. contortum can be distinguished by its pale stems, but greenish shade forms are hard to recognise in the field. The base-rich habitat is characteristic: S. contortum is usually associated with such indicators as Carex pulicaris, Scorpidium revolvens, S. scorpioides and Sphagnum teres.

Section Subsecunda

85

Fig. 19 1–6, Sphagnum contortum: 1, moist fascicle (×3); 2, divergent branch leaves; 3, stem leaves (hatching indicates distribution of fibrils); 4, cells at middle of divergent branch leaf, abaxial side; 5, divergent branch leaf section; 6, stem section. 7–11, S. platyphyllum: 7, divergent branch leaves; 8, stem leaf (hatching indicates distribution of fibrils); 9, cells at middle of divergent branch leaf, abaxial side; 10, divergent branch leaf section; 11, stem section. Leaves ×280, cells ×280.

86

1 Sphagnaceae

24 S. platyphyllum (Lindb. ex Braithw.) Sull. ex Warnst., Flora, 1884 (Fig. 19) S. contortum var. platyphyllum (Lindb. ex Braithw.) Åberg, S. laricinum var. platyphyllum Lindb. ex Braithw. Dioicous. Shoots to 15 cm long, green or yellowish with distinct terminal buds, forming untidy carpets. Stems 0.3–0.7 mm diameter; cortex irregularly 1–2(−3) layers, cells of outer surface mostly with a pore at upper end; cylinder green or brown. Branches 1–3(−4) per fascicle, to 13 mm long, not differentiated into pendent and divergent. Stem leaves erect or spreading, 1.2–2.3 × 0.8–2.0 mm, concave, elliptical, resembling branch leaves; border 2–4(−6) cells wide; patches of narrow cells at basal angles absent; hyalocysts not septate, fibrillose in a zone 80–100% of leaf; abaxial pores 2–5 μm, to 25 per cell, or ill-defined and ± obsolete; adaxial pores absent, or 2–4 μm, 0–6 per cell, ringed and confined to cell angles. Branch leaves 0.9–2.1 × 0.7–2.0 mm, concave, elliptical; border 1–3 cells wide; chlorocysts in section barrel-shaped or lens-shaped, exposed on both surfaces, or just enclosed on adaxial surface; abaxial pores in mid-leaf 2–5 μm, to 40 per cell, or ill-defined and ± obsolete; adaxial pores absent. Perichaetial leaves broadly elliptical-oblong, blunt, fibrillose and porose above. Spores 32–35 μm. Capsules unknown in Britain or Ireland. n = 19. In ± base-rich seasonally wet peaty runnels and swamps, often with Scorpidium revolvens. 0–450 m. Rare, but probably overlooked, Brecon, Pembroke, Cardigan, N. Wales to W. Sutherland and Lewis, S. Kerry, W. Galway, W. Mayo, Fermanagh. 21, H4. GB20 + 12∗ , IR3 + 1∗ . Circumpolar Boreal-montane. Circumpolar, boreal and north temperate, with a somewhat continental distribution on the mainland of Europe. Resembling semi-submerged forms of S. denticulatum, but with relatively broader and more concave stem leaves, more pronounced terminal buds and branches often in fascicles of 1–2. The stem cylinder is usually pale, but may be blackened by swampy habitat. More than one section may be necessary to demonstrate the 2-layered stem cortex: often on a single stem there are parts where the cortex is 2-layered and others where it is 1-layered.

Section 6 Cuspidata (Lindb.) Schlieph. ex Schimp., Syn. Musc. Eur. (ed. 2), 1876 Plants slender to moderately robust. Stems usually 0.3–1.0 mm diameter; cortex 2–3(−4) layers, 25–80 μm wide, hyaline or not, cell walls without fibrils, outer surface without pores; diameter of cortical cells measured at right-angles to radius, 15–40(−60) μm; cylinder in some species strongly differentiated from cortex, in others weakly so. Branches in fascicles of (2−)3–5(−6), in some species not differentiated into pendent and divergent branches, in those that have differentiation 2(−3) divergent, 1–3 pendent; branch cortex with clearly dimorphic cells (except S. lindbergii and submerged forms), cell walls without spiral fibrils; retort cells various, with almost no neck or a moderate or large one, in groups of 1–2. Stem leaves hanging or spreading, usually 0.8–1.6 × 0.5–1.3 mm; border 4–10 cells wide, near

Section Cuspidata

87

apex entire or resorbed; patches of narrow cells at basal angles large, occupying 50–100% of leaf base, hyalocysts not, or hardly septate, variously fibrillose or not; abaxial1 surface ± intact (except S. lindbergii); adaxial surface extensively resorbed near leaf apex, or more rarely with large pores. Branch leaves ovate or lanceolate, concave or straight, in several species altering markedly when dry, becoming erect-patent or squarrose (a character confined to this Section among European Sphagna), usually 0.8–3.5 × 0.4–0.9(−1.2) mm; border intact, 2–6 cells wide; chlorocysts triangular or trapezoid in section, broadly exposed on abaxial surface, with a lesser or absent exposure on adaxial surface; hyalocysts near apex longer than wide (sometimes ± isodiametric in S. tenellum), their abaxial surface near leaf apex sometimes with a large pore at distal angle (usually not); abaxial pores in mid-leaf 0–1(−3) per cell, 2–9 μm (larger in S. tenellum), confined to ends of cell (especially distal end), or occasionally a few at other angles (in some species there are more numerous abaxial pores, but these are then 2–8 μm, unringed, not appressed to commissures); adaxial pores (2−)4–9(−18) μm, 0–10(−12) per cell, faint, unringed, often visible only with intense staining, appressed to commissures (except in S. obtusum). Antheridia on divergent branches. Perichaetial leaves with border intact to apex (except S. lindbergii), hyalocysts fibrillose or not, often resorbed on adaxial surface.

Key to Sphagnum Section Cuspidata 1 Stem leaves with fibrils near apex 2 Stem leaves without fibrils near apex 6 2 Small greenish plants with branches 4–8(−10) mm; branch leaves concave, ovate or broadly ovate, to 1.5 mm long; hyalocysts near apex of branch leaves 20–40 μm wide, 1–4 times as long as wide 25. S. tenellum Habit and colour various, branches often exceeding 10 mm; branch leaves concave or not, ovate or lanceolate, often exceeding 1.5 mm long; hyalocysts near apex of branch leaves less than 20 μm wide, 3–9 times as long as wide 3 3 Colour orange, yellow or golden-brown 4 Colour green or dingy 8 4 Stems darker than leaves, brown or dark brown (occasionally this pigmentation is manifested only in patches); relatively robust plants with branches in dry state 1–3 mm diameter 29. S. pulchrum Stems pale, plants slender or medium-sized, the branches in dry specimens rarely exceeding 1.3 mm diameter 5 5 Stem cortex strongly differentiated; stem leaves ± spreading; branches in fascicles of 3(−4) 28. S. balticum 1

Because the leaves of mature stems hang down in Section Cuspidata the abaxial side is pressed against the stem so that what is technically the abaxial side may be interpreted as the adaxial side. However, in the capitulum the stem leaves are erect.

88

6

7

8

9

10

11

12

1 Sphagnaceae Stem cortex weakly differentiated; stem leaves hanging; branches in fascicles of 4–5 8 Stems dark brown; plants usually brownish; stem leaves widest near the fringed retuse apex 35. S. lindbergii Stems pale; plants of various colours; stem leaves widest near base 7 Terminal buds large, conspicuous; stem leaves conspicuously cleft at apex 34. S. riparium Terminal buds small, ± hidden among capitulum branches; stem leaves entire or somewhat fringed at apex, not cleft 8 Pendent branches weakly or not at all differentiated, not appressed to stems, their leaves resembling those of divergent branches; plants often ± submerged; when growing in drier places the leaves at ends of branches rolled into a sharp cusp; stem leaves usually with fibrils; stem cortex ± clearly differentiated 9 Pendent branches with leaves whitish when moist, clearly differentiated from divergent branches, appressed to stems and ± concealing it; plants rarely submerged; leaves at branch apex not rolled into a cusp; stem leaves usually without fibrils; stem cortex usually very indistinct, occasionally well differentiated 10 Colour dingy olive; hyalocysts of branch leaves with abundant (usually c. 10 per cell) unringed abaxial pores (use stain) 27. S. majus Colour green, rarely dingy olive, hyalocysts of branch leaves with 0–1(−3) ringed abaxial pores per cell, unringed abaxial pores absent 26. S. cuspidatum Stem leaves acute, with margins inrolled at apex to form an apiculus 30. S. fallax Stem leaves obtuse, apices plane or slightly cucullate 11 Pendent branches longer than spreading branches; stem leaves equilaterally triangular, entire at apex; divergent-branch leaves recurved when dry; plants greenish or brightly coloured 31. S. angustifolium Pendent branches shorter than or equal to spreading branches; stem leaves triangular-lingulate, longer than wide, fringed at apex; branch leaves erect-patent but not recurved when dry; plants greenish 12 Adaxial pores of leaves of divergent branches very indistinct even with heavy staining, 2–5 μm 33. S. obtusum Adaxial pores of leaves of divergent branches 5–20 μm, clearly visible with heavy staining, at least near apex of leaf 32. S. flexuosum

25 S. tenellum (Brid.) Bory, Voy. Iˆles Afrique III, 1804 S. molluscum Bruch

(Fig. 20)

Dioicous. Shoots to 10 cm long, green or faintly brownish, forming loose tussocks or growing as scattered plants. Stems 0.3–0.5 mm diameter; cortex

Section Cuspidata

89

Fig. 20 1–7, Sphagnum tenellum: 1, moist fascicle (×3); 2, divergent branch leaves; 3 stem leaves; 4, cells at middle of divergent branch leaf, abaxial side; 5, divergent branch leaf section; 6, divergent branch cortex, surface view showing retort cells; 7, stem section. 8–13, S. cuspidatum: 8, moist fascicle (×3); 9, divergent branch leaves; 10 stem leaves; 11, cells at middle of divergent branch leaf, abaxial side; 12, divergent branch leaf section; 13, stem section. Leaves ×27, cells ×280.

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1 Sphagnaceae

(1−)2–3 layers, clearly differentiated from cylinder, lacking pores on outer surface; cylinder green. Branches 4–8(−10) mm long, (2−)3(−4) per fascicle, of which usually 2 divergent, 1 pendent, the pendent branch small, not appressed to stems, weakly differentiated from divergent branches; retort cells in pairs, with strongly protuberant necks. Stem leaves large for size of plants, 0.9–1.4 × 0.5– 0.7 mm, lingulate, entire, spreading, apices rounded, often ± cucullate; border 5–10 cells wide, at basal angles merging with patches of narrow cells which take up 50–100% of leaf base; hyalocysts fibrillose in upper 40–100% of leaf; abaxial surface intact, or with a few large pores at distal angles of hyalocysts; adaxial surface near apex usually with a single large pore 13–30 μm at distal angle of each cell, occasionally more extensively resorbed. Branch leaves 0.8–1.5 × 0.4– 0.7 mm, ovate, concave, little modified when dry, apex acute or obtuse; border 2–3(−5) cells wide; chlorocysts in section triangular or trapezoid, broadly exposed on abaxial surface, reaching adaxial surface and usually somewhat exposed on it; hyalocysts near leaf apex 1–4 times as long as wide; abaxial pores in midleaf 4–12(−25) μm, 0–1(−2) per cell, when present usually confined to distal angle of cell; adaxial pores faint, unringed, 4–18 μm, 0–2 per cell, confined to ends of cell. Antheridial leaves faintly yellowish. Perichaetial leaves ovate, acute, composed either of uniform vermicular cells, or if cells dimorphic then hyalocysts fibrillose above, intact on abaxial surface, on adaxial surface with large pores one per cell at distal angle. Spores 35–40 μm. Capsules frequent, summer. n = 19, 19 + 2 m∗ . Among other sphagna, particularly S. capillifolium and S. papillosum, on wet heaths and bogs; in high-rainfall areas on sheltered rocky banks. 0–1090 m. Common in the north and west, local in S. E. England. 92, H39. GB586 + 76∗ , IR186 + 15∗ . Suboceanic Boreo-temperate. Circumpolar, suboceanic; S. America. Usually easy to recognise in the field. Good field characters are the short branches, ovate concave branch leaves, weak differentiation between pendent and divergent branches, and the relatively large spreading stem leaves. Microscopically, the necks of the retort cells are more protuberant than in any other European Sphagnum. S. tenellum is a somewhat aberrant member of Section Cuspidata, sometimes placed on its own in Section Mollusca Schlieph. ex Casares-Gil.

26 S. cuspidatum Ehrh. ex Hoffm., Deutschl. Fl., 1796 S. viride Flatberg

(Fig. 20)

Dioicous. Shoots to 15 cm long in terrestrial plants, often much longer in aquatic forms, green or slightly brownish, forming flaccid wefts. Stems 0.4–0.8 mm diameter; cortex 2–3 layers, ± clearly differentiated from cylinder, lacking pores on outer surface; cylinder green. Branches 3–5(−6) per fascicle, straight or sometimes strongly curved, not or hardly differentiated into pendent and divergent. Stem leaves 0.9–1.3 × 0.6–1.0 mm, rounded-triangular, entire, variously hanging or spreading; border 4–9 cells wide, merging at basal angles with patches of

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narrow cells which take up 60–100% of leaf base; hyalocysts fibrillose in upper (0−)20–40% of leaf; abaxial surface intact; adaxial surface near leaf apex either with 3–5 large (8–25 μm) pores per cell, or ± extensively lacking. Branch leaves 1.5–3.5 × 0.3–0.7 mm, lanceolate or ovate, sometimes little modified when dry, or strongly recurved except at the cuspidate branch tips; border 3–6 cells wide; chlorocysts in section triangular or trapezoid, broadly exposed on abaxial surface, reaching adaxial surface and often moderately exposed on it; abaxial pores in mid-leaf 2–6 μm, 0–1(−3) per cell, ringed, usually at distal angle of cell, less often at proximal end or other angles; adaxial pores faint, unringed, 4–8 μm, 4–10 per cell, confined to cell angles or distributed along commissures. Antheridial leaves brown, contrasting with green ordinary leaves. Perichaetial leaves oblong, obtuse, fibrillose above; abaxial surface intact; adaxial surface with pores or more extensive resorption near leaf apex. Spores 32–37 μm. n = 19 + 2 m∗ , 19 + 4 m. Capsules occasional, summer. On wet peaty ground, usually in pools and runnels on acid bogs and moorland; also among Cyperaceae by oligotrophic lakes and pools, or free-floating as an aquatic. 0–1030 m. Throughout the British isles; common in the north and west, local in S. E. England. 105, H40. GB805 + 61∗ , IR216 + 24∗ . European Boreo-temperate. Circumpolar, mainly in the boreal zone. In the field the best marks of distinction from S. recurvum agg. (species 30–32) are the narrowly lanceolate leaves, the absence of well defined pendent branches, and, in terrestrial forms, the tightly rolled leaves of the cuspidate branch apices. Submerged forms are sometimes highly modified, with a flaccid habit that has been likened to a drowned kitten; such forms may have ± denticulate leaf margins. For the distinction from S. majus see under that species. Sphagnum viride is a segregate of S. cuspidatum described by Flatberg (K. Norske Vidensk. Selsk. Skr. 1, 1–64, 1988). The distinction is entirely morphometric and comparative, with S. viride being greener, with arcuate rather than falcate branches in terrestrial forms. In S. cuspidatum the branch leaves are less than 0.28 times as wide as long, with hyalocysts more than 8 times as long as wide. In S. viride the branch leaves are more than 0.28 times as wide as long, with hyalocysts less than 8 times as long as wide. The defining characters are neither clear cut nor well correlated. S. viride cannot be maintained as a taxon distinct from S. cuspidatum.

27 S. majus (Russow) C. E. O. Jensen, Bot. For. Festskr., 1890 S. cuspidatum var. majus Russow, S. dusenii Warnst.

(Fig. 21)

Dioicous. Shoots to 25 cm long, dull brownish green, forming loose wefts. Stems 0.6–0.8 mm diameter; cortex 2–3 layers, ± clearly differentiated from cylinder, lacking pores on outer surface; cylinder green. Branches 4–5 per fascicle, not or hardly differentiated into pendent and divergent. Stem leaves 0.9–1.4 × 0.8– 1.0 mm, rounded-triangular, entire, variously hanging or spreading; border 4–8 cells wide, merging at basal angles with patches of narrow cells which take up 60– 100% of leaf base; hyalocysts fibrillose in upper 20–40% of leaf; abaxial surface

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Fig. 21 1–5, Sphagnum majus: 1, divergent branch leaves; 2, stem leaves; 3, cells at middle of divergent branch leaf, abaxial side; 4, divergent branch leaf section; 5, stem section. 6–10, S. balticum: 6, divergent branch leaves; 7, stem leaves; 8, cells at middle of divergent branch leaf, abaxial side; 9, divergent branch leaf section; 10, stem section. Leaves ×27, cells ×280.

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93

intact; adaxial surface near leaf apex extensively resorbed, often ± completely lacking. Branch leaves 1.7–3.0 × 0.6–0.8 mm, ovate or lanceolate, little modified when dry; border 3–5 cells wide; chlorocysts in section triangular or trapezoid, broadly exposed on abaxial surface, reaching adaxial surface and often moderately exposed on it; abaxial pores in mid-leaf 5–8 μm, (2−)8–18 per cell, unringed, many of them in middle of cell surface, not appressed to commissures; adaxial pores faint, unringed, 5–7 μm, 0–6 per cell, confined to cell angles. Antheridial leaves rusty-brown, contrasting with ordinary leaves. Perichaetial leaves oblong, obtuse, fibrillose near apex; abaxial surface intact; adaxial surface of hyalocysts resorbed near leaf apex. Spores 27–38 μm. n = 38. Capsules very rare. Semi-submerged in bog hollows and beside pools. Very rare but doubtless overlooked, S. Northumberland, E. Inverness, W. Sutherland and formerly Angus. 4. GB3 + 1∗ . Circumpolar Boreal-montane. Circumpolar in the boreal zone; distribution in Europe mainly continental. In the field resembling S. cuspidatum, to which it is closely allied. The main distinguishing feature is the dingy brownish-green colour. S. cuspidatum is predominantly green except for the antheridial leaves. Microscopically the numerous abaxial pores are an easy mark of distinction, but because they lack rings they are hard to see without stain.

28 S. balticum (Russow) Russow ex C. E. O. Jensen, Bot. For. Festskr., 1890 (Fig. 21) S. recurvum ssp. balticum Russow Dioicous. Shoots to 15 cm long, greenish orange or yellowish, forming loose carpets. Stems 0.3–0.7 mm diameter; cortex 2–3 layers, clearly differentiated from cylinder, lacking pores on outer surface; cylinder yellowish, pale. Branches 3(−4) per fascicle, of which 2 divergent, 1(−2) pendent; pendent branch sometimes weakly differentiated from divergent, more often whitish, appressed to stems. Stem leaves 0.9–1.2 × 0.5–0.8 mm, lingulate, entire, ± spreading, the margins at apex inrolled so that until flattened under a cover-slip the leaf appears triangular; border 4–7(−9) cells wide, merging at basal angles with patches of narrow cells which take up to 60–80% of leaf base; hyalocysts fibrillose in upper 20– 50% of leaf; abaxial surface intact; adaxial surface near leaf apex resorbed and usually ± completely lacking. Branch leaves 0.9–1.7(−2.4) × 0.4–0.7 mm, ovate, little modified when dry; border 2–3 cells wide; chlorocysts in section ± triangular, broadly exposed on abaxial surface, reaching adaxial surface and sometimes slightly exposed on it; abaxial pores in mid-leaf 5–9 μm, 0–1 per cell, when present usually confined to distal angle of cell (but in a Northumberland population plants occur with up to 9 unringed abaxial pores resembling those of S. majus); adaxial pores faint, unringed, 5–8 μm, 5–12 per cell, distributed along commissures. Antheridial leaves brown, contrasting with ordinary leaves. Perichaetial leaves oblong, weakly fibrillose above, hyalocysts ± extensively resorbed on adaxial

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surface near leaf apex. Spores 26–28 μm. Capsules not known in Britain. n = 19 + 2 m. Ditches and depressions in ombrotrophic bogs. 0–660 m. Very rare, Cardigan, S. W. Yorkshire, S. Northumberland, Dumfries, S. Aberdeen, E. Inverness, old records from Cheshire, W. Lancashire. 8. GB6 + 2∗ . Circumpolar Boreoarctic Montane. Circumpolar, slightly continental. Superficially like a strongly coloured, slender form of S. fallax. Useful field characters are the ± spreading stem leaves and the smaller number of branches per fascicle. Most British plants have the branches regularly in fascicles of 3, but plants from one site had branches mainly in fascicles of 4.

29 S. pulchrum (Lindb. ex Braithw.) Warnst., Bot. Centralb., 1900 (Fig. 22) Dioicous. Shoots to 15 cm long, orange-brown, orange or yellow-green, forming loose carpets and ‘lawns’. Stems 0.5–0.8 mm diameter; cortex 2–3 layers, ± clearly differentiated from cylinder but not hyaline, lacking pores on outer surface; cylinder brown, darker than leaves, or sometimes partly green. Branches regularly 4 per fascicle, 2 divergent, 2 pendent; pendent branches short, not exceeding 13 mm long; divergent branches also rather short, to c. 17 mm long, in dried specimens generally 1.5–2.0 mm wide (including leaves) and appearing rather stubby. Stem leaves 0.9–1.2 × 0.7–0.9 mm, triangular, hanging or spreading, the margins inrolled at apex to form a pronounced cusp; border 5–9 cells wide, merging at basal angles with patches of narrow cells which take up 60–80% of leaf base; hyalocysts fibrillose in upper 20–50% of leaf; abaxial surface intact; adaxial surface near leaf apex resorbed and lacking. Branch leaves 1.2–1.8 × 0.5–0.9 mm, ovate, appressed in 5 distinct rows when wet, much modified and flexuose at margin when dry, erect-patent (but not recurved) so that branch appears stubby; border 2–4 cells wide; chlorocysts in section triangular, broadly exposed on abaxial surface, completely enclosed on adaxial surface; abaxial pores in mid-leaf 3–8 μm, 0–1(−2) per cell, when present usually confined to distal angle of cell; adaxial pores faint, unringed, 4–8 μm, 3–9 per cell, confined to cell angles or distributed along commissures. Antheridial leaves bright orange-brown, contrasting markedly with other leaves. Perichaetial leaves ovate-oblong, intact on both surfaces, lacking fibrils or pores. Spores 27–30 μm. n = 19. Capsules unknown in Britain or Ireland. In wetter parts of raised bogs in western Britain and Ireland; also on valley bogs in S. E. Dorset. 0–280 m. Rare but locally abundant. 14, H6. GB26 + 3∗ , IR15. Suboceanic Boreo-temperate. Atlantic and sub-Atlantic regions of Europe and eastern N. America, Japan. A distinctive species, the bright colour rapidly attracting attention. In the field, the 5-ranked branch leaves distinguish it from S. denticulatum; the dark stems distinguish it from S. balticum and S. fallax; the triangular stem leaves distinguish it from S. lindbergii. Microscopically it is close to S. fallax but can be distinguished by the combination of fibrillose stem leaves and branch leaves less than 2.5 times as long as wide (more than 2.7 times as long as wide in S. fallax).

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Fig. 22 1–6, Sphagnum pulchrum: 1, moist fascicle (×3); 2, divergent branch leaves; 3, stem leaves; 4, cells from middle of divergent branch leaf, abaxial side; 5, divergent branch leaf section; 6, stem section. 7–9, S. obtusum: 7, divergent branch leaves; 8, stem leaves; 9, cells from middle of divergent branch leaf, abaxial side. Leaves ×27, cells ×280.

30–32 S. recurvum agg. S. intermedium auct. non Hoffm. Dioicous. Shoots to 20 cm long, green or orange, in loose tussocks or low carpets. Stems 0.4–0.9 mm diameter; cortex 2–3 layers, weakly to moderately differentiated from cylinder, lacking pores on outer surface; cylinder green or pale orange, rarely pinkish. Branches 4–5(−6) per fascicle, straight or hanging, clearly differentiated into 2(−3) divergent and 2–3(−4) pendent; pendent branches appressed to stem and ± whitish. Stem leaves 0.6–1.2 × 0.6–1.0 mm, triangular or

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triangular-lingulate, mostly hanging and appressed to stem; apices acute or rounded; border 4–8 cells wide, merging at basal angles with patches of narrow cells which take up 60–80% of base; hyalocysts without fibrils or occasionally with fibrils in upper 20–40% of leaf; abaxial surface intact; adaxial surface near leaf apex resorbed and lacking. Branch leaves 1.2–2.1 × 0.3–0.8 mm, ovate or narrowly ovate, 5-ranked or not, appressed when wet and either erectpatent or recurved when dry; border 2–4 cells wide; chlorocysts in section triangular or trapezoid, broadly exposed on abaxial surface, reaching adaxial surface or not, not or moderately exposed on it; abaxial pores in mid-leaf 4–9 μm, 0–1(−2) per cell, ringed, when present usually confined to distal angle of cell; adaxial pores faint, unringed, 5–9 μm, 3–7 per cell, ± confined to cell angles, often larger, ringed and perforate near leaf apex. Antheridial leaves yellowish or orange, contrasting markedly with ordinary leaves. Perichaetial leaves ovate or oblong, ± obtuse with a small apiculus, intact on both surfaces, lacking fibrils and pores. The Sphagnum recurvum group comprises three species in Britain and Ireland, or five species if the taxonomy of Flatberg (Lindbergia 19, 96–110, 1992) is followed. S. recurvum P. Beauv. is a robust American taxon absent from Europe, with fringed rounded stem leaves and the branch leaves strongly recurved (i.e. squarrose) when dry. The aggregate can generally be recognised by the pale stem and widely spaced, ± triangular, hanging stem leaves. Members of the S. recurvum group are most likely to be confused with S. cuspidatum but can almost always be distinguished by their clearly differentiated pendent branches, which are whitish and appressed to the stems. Rarely, when growing semi-submerged, the pendent branches may lose their distinctness and the stem leaves may develop pronounced fibrils. The stem section and shape of the branch leaves will usually distinguish such plants.

30 S. fallax (H. Klinggr.) H. Klinggr., Vers. Topogr. Fl. Westpreuss., 1880 (Fig. 23) S. recurvum var. mucronatum (Russow) Warnst., S. recurvum var. brevifolium ¨ (Lindb. ex Braithw.) Warnst. p.p., S. brevifolium (Lindb. ex Braithw.) Roll emend. Flatberg, S. isoviitae Flatberg Shoots green, yellow or orange, often forming extensive ‘lawns’. Stems pale or slightly reddish; cortex slightly to moderately well differentiated. Branch bases with or without red pigment. Pendent branches ± equal in length to divergent branches, sometimes shorter or longer. Stem leaves 0.8–1.1 × 0.6– 1.0 mm, triangular or triangular-lingulate, acute, with margins inrolled above to form a distinct cusp, rarely ± rounded at apex but even then with a weak cusp; apices not fringed. Chlorocysts of divergent-branch leaves triangular in section, reaching adaxial surface or enclosed. Abaxial pores of pendentbranch leaves 5–10(−14) μm, very rarely exceeding 12 μm. Spores 27–30 μm. n = 19 + 2 m∗ . Capsules occasional, August. Occurring in a wide range of permanently moist or wet acid habitats, in wet fields, bogs, by streams, in ditches, woods, swamps, on wet moorland and flushed banks. It occurs in pools and runnels

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97

Fig. 23 1–4, Sphagnum fallax: 1, moist fascicle (×3) 2, stem leaf; 3, divergent branch leaf; 4, divergent branch leaf cells, abaxial side. 5–8, S. angustifolium: 5, moist fascicle (×3) 6, stem leaf; 7, divergent branch leaf; 8, divergent branch leaf cells, abaxial side. Leaves ×50, cells ×280.

in bogs. 0–1000 m. 110, H35. GB1053 + 65∗ , IR145 + 9∗ . European Boreo-temperate. Circumboreal. S. fallax is a variable species with a complex pattern of intraspecific variation. Flatberg (J. Bryol. 17, 1–13, 1992) distinguished three taxa within S. fallax as understood here, namely S. fallax, S. isoviitae and S. brevifolium. The distinctions between these segregates present great difficulties because the defining characters are not clear-cut and often occurr in ˚ ‘wrong’ combinations. A subsequent genetic study by Flatberg’s group (S. M. Sastad et al., System. Bot. 24, 95–107, 1999) confirmed the distinctness of S. fallax from S. angustifolium and S. flexuosum but suggested that the segregates of S. fallax form a single interbreeding population. Accordingly, Flatberg’s segregates are not recognised here, even at the subspecific rank (S. fallax ssp. isoviitae (Flatberg) M. O. Hill) used in Blockeel & Long (1998). The form originally described as S. isoviitae has reddish branch bases and branch leaves that are strongly 5-ranked, erect-patent but not recurved in the dry state, with chlorocysts distinctly enclosed

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on the adaxial surface. It can be confused with S. pulchrum (q.v. for differences). The more usual forms of S. fallax have branch bases scarcely pigmented, branch leaves weakly or not 5-ranked, distinctly recurved in the dry state, with chlorocysts reaching the adaxial surface.

31 S. angustifolium (C. E. O. Jensen ex Russow) C. E. O. Jensen, Bih. Kongl. Svenska Vetensk-Akad. Handl., 1896 (Fig. 23) S. recurvum var. tenue H. Klinggr., S. parvifolium (Warnst.) Warnst. Slightly more slender than S. fallax and S. flexuosum. Shoots green, yellowish or orange, forming loose carpets and lax tufts. Stems green or occasionally redflecked; cortex indistinctly differentiated. Branch bases often reddish when well illuminated. Pendent branches longer than divergent branches. Stem leaves 0.6– 0.8 × 0.6–0.8 mm, triangular, as wide as long, rounded with apices slightly cucullate, not or scarcely fringed. Divergent-branch leaves 5-ranked or not, recurved when dry; chlorocysts triangular in section, reaching adaxial surface. Abaxial pores of pendent-branch leaves 7–20(−30) μm, at least some exceeding 12 μm. Capsules not reliably reported in Britain or Ireland. Soligenous marshes, flushed moorland banks and woods, often mixed with S. fallax but not occurring in the more acid habitats of the latter. 0–500 m. Throughout Britain and Ireland, scarce in the south; frequent to common in upland areas but poorly recorded. 41, H8. GB38 + 8∗ , IR9. Circumpolar Boreal-montane. Circumboreal, widespread in continental interiors. When growing in woodland, S. angustifolium has markedly convex capitula, giving the plants a characteristic ‘pom-pom’ appearance. The relatively short, triangular, stem leaves with rounded apices can be readily observed in the field. Dried specimens can be distinguished from S. flexuosum by their recurved branch leaves.

32 S. flexuosum Dozy & Molk., Prodr. Fl. Bat. 2, 1851 S. recurvum var. amblyphyllum (Russow) Warnst.

(Fig. 24)

Shoots green, forming loose tufts and low carpets. Stems pale, cortex very indistinctly differentiated. Branch bases lacking red or brown pigment. Pendent branches shorter than or equal to divergent branches. Stem leaves 0.8–1.2 × 0.6– 0.9 mm, triangular-lingulate or lingulate, longer than wide; apices rounded, plane or slightly cucullate, ± extensively fringed because of resorption. Leaves of divergent branches when dry erect-patent with wavy margins, not or scarcely recurved; chlorocysts triangular or trapezoid in section, reaching adaxial surface and often exposed on it. Abaxial pores of pendent-branch leaves 5–20(−30) μm, sometimes with many exceeding 12 μm. Marshes, boggy moorland and damp woods, generally in more basic habitats than S. fallax though often mixed with it. 0–500 m. Probably throughout Britain and Ireland, but scarcer than S. fallax except in parts of southern England, very rare in Ireland, W. Galway and formerly W. Cork. 53,

Section Cuspidata

99

Fig. 24 Sphagnum flexuosum: 1, moist fascicle (×3); 2, divergent branch leaves; 3, stem leaf; 4, cells at middle of divergent branch leaf, abaxial side; 5, divergent branch leaf section; 6, stem section. Leaves ×50, cells ×280.

H2. GB47 + 12∗ , IR1 + 1∗ . European Boreo-temperate. Circumboreal but scarce or absent in continental interiors. This is the greenest species in the S. recurvum aggregate, never with reddish pigments or orange leaves, developing at most a faint yellowish tinge. The rounded, fringed stem leaves, longer than wide, can be observed in the field by pulling off the capitulum.

33 S. obtusum Warnst., Bot. Zeitung (Berlin), 1877 (Fig. 22) Similar to S. flexuosum, differing in pore structure and slightly more robust habit. Stem leaves rounded-triangular, obtuse, ± fringed at apex because of resorption. Leaves of divergent branches with very small unringed abaxial pores, 2–5 μm, 0–14 per cell in one or two rows along middle of cell surface, not appressed against commissures; adaxial pores also very small, unringed, 2–5 μm, 0–8 per cell, appressed against commissures or not, often very indistinct. Abaxial pores of pendent branch leaves 3–5(−8) μm. Lowland. Formerly in W. and S. Lancashire but thought to be extinct through drainage. 2. GB2∗ . Circumpolar Boreo-arctic Montane. Circumpolar; a boreal species with a somewhat eastern distribution in Europe. The characteristic unringed abaxial pores are usually easiest to see near the margin in the lower parts of the leaves but can be present in middle of leaves. Intense staining is

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1 Sphagnaceae

required: the leaf should be almost black. When a leaf of S. flexuosum is stained in this way the relatively large adaxial pores are easily visible, at least near leaf apex.

¨ 34 S. riparium Ångstr., Ofvers F¨ohr. Kongl. Svenska Vetensk.-Akad., 1864 (Fig. 25) S. intermedium var. riparium (Ångstr.) Lindb. Dioicous. Shoots to 25 cm long, green or faintly brownish, with large terminal buds, forming loose green carpets. Stems 0.5–1.0 mm diameter; cortex 2–3 layers, weakly differentiated from cylinder, lacking pores on outer surface; cylinder green. Branches in fascicles of 4–5, 2(−3) divergent, 2–3 pendent. Stem leaves mostly hanging, 1.3–1.6 × 0.9–1.3 mm, triangular or triangular-lingulate, conspicuously cleft at apex; border 3–8 cells wide, merging at basal angles with patches of narrow cells which take up 60–80% of leaf base; hyalocysts lacking fibrils; adaxial surface of hyalocysts extensively resorbed and lacking in upper half of leaf, both surfaces being resorbed near apical cleft. Branch leaves 1.3–3.0 × 0.5–0.9 mm, ovate, somewhat recurved when dry; border 2–4(−6) cells wide; chlorocysts in section triangular or trapezoid, broadly exposed on abaxial surface, reaching adaxial surface and often moderately exposed on it; near apex of leaf there are no hyalocysts, undifferentiated chlorocysts combining to form a snout 100–500 μm long; abaxial pores dimorphic, in upper and mid-leaf 4–6 μm, 0–1 per cell, confined to distal angles of cells, in middle and lower leaf near margin often consisting of membrane gaps 14–28 μm, also confined to distal angles, these being repeated on adaxial surface to give a colander-like appearance; in the pendent branch leaves, the colanderlike membrane gaps occur throughout upper part of leaves, giving them a striking appearance when stained; adaxial pores (except for large perforated pores opposite abaxial membrane gaps) 3–15 μm, faint, unringed, 0–14 per cell, distributed along commissures. Antheridial leaves brownish. Perichaetial leaves oblong, entire; apices rounded with small apiculus; hyalocysts intact on both surfaces, lacking fibrils and pores. Spores 25–27 μm. Capsules very rare, summer. n = 19 + 4 m. In marshes and by streams, often among rushes on moderately nutrient-rich ground. 0–750 m. Rare, northern England to Shetland, markedly eastern and showing a preference for higher altitudes; casual in Berkshire during the 1960s. 17. GB15 + 8∗ . Circumpolar Boreal-montane. Circumpolar, common in the Arctic, more scattered further south. In the field the stem leaves are unmistakable, but this plant is not conspicuous and can be overlooked as a robust S. girgensohnii or S. fallax.

¨ 35 S. lindbergii Schimp. ex Lindb., Ofvers F¨ohr. Kongl. Svenska Vetensk.-Akad., 1857 (Fig. 25) Autoicous. Shoots to 20 cm long, often fulvous brown but sometimes greenish in spring after snow-melt, with large terminal buds, forming low carpets. Stems 0.5–0.9 mm diameter, dark brown or almost black; cortex 3–4 layers, strongly differentiated from cylinder, lacking pores on outer surface; cylinder dark brown.

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Fig. 25 1–7, Sphagnum riparium: 1, divergent branch leaves; 2, stem leaf; 3, cells at middle of divergent branch leaf, abaxial side; 4, cells at middle of pendent branch leaf, abaxial side; 5, cells near apex of divergent branch leaf, adaxial side; 6, divergent branch leaf section; 7, stem section. 8–13, S. lindbergii: 8, divergent branch leaf; 9, stem leaves; 10, cells at middle of divergent branch leaf, abaxial side; 11, divergent branch leaf section; 12, stem cortex, surface view; 13, stem section. Leaves ×27, cells ×280.

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Branches in fascicles of 4–5(−6), not clearly differentiated into pendent and divergent, or occasionally well differentiated; cells of branch cortex not clearly differentiated into retort and non-retort cells, almost all cells having a pore at distal end. Stem leaves hanging, 1.3–1.6 × 0.9–1.5 mm, cuneate or rectangular, with retuse, conspicuously tattered apices; border 3–7 cells wide, continued up sides of leaf but not extending across apex, at basal angles merging with patches of narrow cells which take up 80–100% of leaf base; hyalocysts lacking fibrils, extensively and equally resorbed, both surfaces being largely absent in upper leaf. Branch leaves 1.3–2.5 × 0.5–0.8 mm, narrowly ovate, not recurved when dry; border 3–5 cells wide; chlorocysts in section triangular or somewhat barrel-shaped, with a wide abaxial exposure, not exposed on adaxial surface; abaxial pores 3–8 μm, 0–1(−2) per cell, when present normally confined to distal angle of cells; adaxial pores 3–8 μm, faint, unringed, (0−)4–10 per cell, in cell angles or distributed along commissures. Antheridial leaves slightly darker than others, not conspicuous. Perichaetial leaves oblong, either obtuse and entire or retuse and ± fringed at apex, lacking fibrils, extensively resorbed on both surfaces near apex. Spores 29– 32 μm. Capsules very rare, summer. n = 10, 19 + 2 m. In montane flushes. Rarely below 600 m and ascending to 1000 m. Rare, Highlands of Scotland from Mid Perth and Angus to W. Sutherland and Shetland. 10. GB16 + 1∗ . Circumpolar, common in the northern boreal zone and Arctic, scattered further south. When the colour is bright orange-brown S. lindbergii is conspicuous. The dark brown stems and usually cuneate, fringed stem leaves make it unmistakable on close examination.

Class 2 Andreaeopsida

Protonemata thalloid. Plants acrocarpous. Seta absent, capsule joined directly to foot and exserted from perichaetium by elongation of pseudopodium (stalk of archegonium); capsule dehiscing by 4(−8) longitudinal slits; spore sac endothecial in origin, overtopping columella, no air cavities between spore sac and capsule wall; calyptrae small. One family.

2 Andreaeales 2 Andreaeaceae One or possibly two genera.

2 ANDREAEA HEDW., SP. MUSC. FROND., 1801 Reddish brown to purple or blackish small to medium-sized tuft- or cushionforming plants. Stems fragile, lacking central strand. Leaves straight to falcate, ovate to narrowly lanceolate or panduriform, abruptly narrowed above basal part to long or short limb or not, apex acuminate to rounded; margins entire or denticulate; costate or ecostate; basal cells short to elongate, walls often sinuose and/or pitted, cells above rounded or quadrate, incrassate, smooth or papillose. Plants usually of acidic rocks in cool temperate, oceanic and sub-polar regions. A worldwide genus of about 50 species. Derivation: named after J. G. R. Andreae (1724–1793), an apothecary of Hanover. The following descriptions are modified from those by B. M. Murray in her monograph of the genus in the British Isles (J. Bryol. 15, 17–82, 1988).

1 Leaves ecostate 2 Leaves costate 6 2 Basal margins of leaves denticulate 1. A. alpina Basal margins of leaves entire or weakly crenulate 3 3 Basal marginal cells of leaves rectangular, other basal cells strongly sinuose and strongly pitted, spores mostly 13–19 μm, very rare high altitude plant 5. A. sinuosa 103

2 Andreaeaceae

104

4

5

6

7

8

9

10

Basal marginal cells oblate to shortly rectangular, other basal cells not or hardly sinuose, pitted or not, spores mostly 20–26 μm (12–21 μm in A. mutabilis) 4 Spores 12–21 μm, leaf bases hardly sheathing, often with patch of yellow cells at base, basal cells hardly pitted, perigonia numerous, crimson 4. A. mutabilis Spores mostly 20–26 μm, leaf bases sheathing, lacking patch of yellow cells at base, basal cells usually pitted 5 Leaves usually subfalcate to falcate-secund, papillae usually prominent at least abaxially on upper leaves, frequent plant 2. A. rupestris Leaves usually straight, papillae usually low or absent, very rarely prominent, very rare high altitude plant 3. A. alpestris Leaf margins papillose-crenulate to serrate throughout, cells papillose 10. A. nivalis Leaf margins entire or very rarely dentate above, cells smooth 7 Spores (10−)11–19(−23) μm, basal cells mostly rectangular, longer than cells above, walls little pitted, rarely slightly sinuose, dioicous 9. A. blyttii Spores more than 20 μm, basal cells mostly quadrate, rounded or oblate, ± similar to cells above (sometimes rectangular near costa or margins), walls often strongly pitted and sinuose, autoicous 8 Leaves gradually tapering to apex, perichaetial bract cells smooth, very rare high altitude plant 7. A. frigida Leaves ± abruptly narrowed to limb, perichaetial bract cells usually papillose 9 Spores mostly 26–36 μm, costa more than 1/3 width of leaf base, poorly defined above, doubtfully British plant A. crassinervia (p. 113) Spores mostly 36–90 μm, costa less than 1/3 width of leaf base, well defined above or not 10 Spores mostly 50–90 μm, leaf cells distinct in upper part of limb, inner perichaetial bracts with low rounded papillae 8. A. megistospora Spores mostly 36–52 μm, leaf cells indistinct in upper part of limb or if distinct then inner perichaetial bracts without or with only low sparse papillae 6. A. rothii

Subgenus 1 Andreaea Perichaetial bracts differentiated from stem leaves, convolute. Section 1 Andreaea Leaves ecostate. 1 A. alpina Hedw., Sp. Musc. Frond., 1801 (Fig. 26) Autoicous. Reddish brown to purplish black tufts or patches, 1–6(−8) cm high. Leaves imbricate when dry, patent to spreading when moist, larger and less

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Fig. 26 1–4, Andreaea alpina: 1, moist shoot tip with sporophyte (×25); 2, leaves (×40); 3, cells at widest part of leaf; 4, basal marginal cells. 5–8, A. alpetris: 5, leaves (×80); 6, basal cells; 7, basal marginal cells; 8, upper cells. Cells ×420.

crowded on capsule-bearing stems, ovate-spathulate to panduriform, widest at or above middle, narrowed to short to long acute to obtuse apex; margins plane to incurved, denticulate from near base to middle of leaf constriction, entire above; costa lacking; basal cells rectangular to narrowly rectangular, walls strongly incrassate, pitted, sinuose, transition from basal to upper cells ± abrupt, upper cells rounded to oval, smooth, 8–10 μm wide. Perichaetial bracts differentiated from stem leaves, convolute. Spores 26–38 μm but frequently aborted. Capsules occasional to common, summer. On moist to continuously dripping rocks in streams, on ledges, cliffs, moist and periodically irrigated outcrops and boulders, in montane areas in acidic to mildly basic situations. 60–1300 m. Rare in S. Wales, frequent or common in N. W. Wales, Lake district and the Scottish Highlands, extending north to Shetland, rare in eastern Ireland, frequent in the far west. 39, H12. GB176 + 34∗ , IR22 + 10. Austria, Faeroes, France, Norway, Greenland, western

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S. America from Colombia southwards, Tasmania, New Zealand, cold temperate and sub-antarctic Southern Hemisphere islands. Easily identified by its large size and panduriform ecostate leaves with margins denticulate below.

2 A. rupestris Hedw., Sp. Musc. Frond., 1801 A. petrophila Ehrh. Autoicous. Green-bronze to red-brown or black often coalescing tufts, 0.5–3.0 cm high. Leaves imbricate when dry, patent or often secund or falcate-secund when moist; straight to falcate, ovate to oblong-lanceolate, little constricted above base to panduriform, widest above or below constriction, upper part short to long, obtuse to acute; margins plane or ± incurved; costa lacking; cells incrassate, basal rectangular to narrowly rectangular, walls pitted, not sinuose, basal marginal cells oblate to rectangular, transition to upper cells ± abrupt, cells above quadrate to shortly rectangular, walls usually strongly pitted, characteristically with prominent colourless papillae on abaxial side but sometimes without, c. 8–10 μm wide. Perichaetial bracts larger than stem leaves, convolute, cells usually strongly papillose. Turgid green spores usually 26–32(−48) μm but frequently aborted. Capsules common, summer. n = 9 + m, 10, 11. Leaves lanceolate or occasionally panduriform, gradually narrowed to short or long obtuse to acute apex, frequent or common plant var. rupestris Leaves abruptly narrowed from ovate or panduriform basal part to long acute apex, very rare plant var. papillosa Var. rupestris (Fig. 27) Cushions, rarely more than 3 cm high. Leaves tapering to short or long apex; papillae when present longer than wide but rarely twice as long as wide. On dry to periodically moist neutral to acidic rocks, cliffs, walls, also in snow-beds, very rarely on lithosols. 0–1330 m. W. Cornwall (old record), Devon, frequent or common in western and northern Britain from Wales north to Shetland, occasional in N. E. Ireland, rare elsewhere. 62, H20. GB454 + 77∗ , IR40 + 13∗ . Widespread in the Northern Hemisphere, C. and S. America, southern Africa, Tasmania, New Zealand, Antarctica. Var. papillosa (Lindb.) Podp., Consp. Musc. Eur., 1954 A. obovata var. papillosa (Lindb.) Nyholm

(Fig. 27)

Plants small (in Britain). Leaves from ovate basal part abruptly narrowed to often very long narrow acute upper part; cells with prominent colourless papillae often more than twice as long as wide, rarely low and inconspicuous. On acidic rocks in mountains. Very rare, Merioneth, Caernarfon, Cumberland (old record).

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Fig. 27 1–5, Andreaea rupestris var. rupestris: 1, leaves; 2, basal marginal cells; 3, basal cells; 4, upper cells; 5, section of upper part of leaf. 6, A. rupestris var. papillosa: leaves. Leaves ×80, cells ×420.

3. GB2 + 1∗ . Austria, Finland, Norway, Poland, Svalbard, Sweden, N. Russia, arctic Asia, N. America. A. rupestris var. rupestris is polymorphic but can usually be distinguished from other ecostate species by its falcate leaves with pitted non-sinuose basal cells and papillose upper cells.

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Closely related to A. alpestris from which stunted forms may be difficult or impossible to separate. Var. papillosa is distinguished from var. rupestris by the leaves abruptly narrowed to a long upper part. Most long-tipped material from Britain has gradually tapering leaves and is referable to var. rupestris. Typically, var. papillosa is a robust plant and British material identified as var. papillosa, at the southern edge of its distribution, is depauperate.

3 A. alpestris (Thed.) Schimp. in Bruch et al., Bryol. Eur., 1855 (Fig. 26) A. petrophila var. alpestris Thed., A. rupestris var. alpestris (Thed.) Sharp Reportedly autoicous. Small brown, brown-black to black, occasionally reddish cushions or mats, to 1 cm high (in Britain). Leaves imbricate, very rarely falcate distally, stiff or soft when dry, widely spreading from middle when moist, lanceolate, usually widest near to and little constricted above base, rarely panduriform, apex straight or occasionally turned to one side, short, incurved, obtuse, rarely acute; margins plane or slightly incurved, entire; costa absent; basal cells shortly rectangular, weakly pitted, not sinuose, basal marginal cells oblate to rectangular, transition to upper cells very gradual, upper cells ± quadrate, walls non-pitted, brownish papillae present but low, inconspicuous and irregular on abaxial side, also on adaxial side where cells bistratose, cells (7−)8–10(−11) μm wide. Perichaetial bracts larger than stem leaves, convolute, cells with low papillae. Spores (21−) 22–26(−32) μm, frequently aborted. Capsules occasional, summer. On periodically moist rock or wet lithosols. 700–1335 m. Very rare, Angus, S. Aberdeen, Banff, Inverness, E. Ross. 6. GB6 + 4∗ . Montane and northern Europe from 40◦ N in Spain north to Fennoscandia, Asia, N. America, Greenland. A. alpestris is recognisable from the thread-like shoots, which are usually a soft brown-black or occasionally glossy black colour, the leaves are usually straight and obtuse. Microscopically, it is characterised by mostly non-pitted cells with inconspicuous papillae. Most British material identified as A. alpestris is A. rupestris var. rupestris or A. mutabilis. Whether the plant should be treated as a distinct species or as a variety of A. rupestris is debatable.

4 A. mutabilis Hook. f. & Wilson, Lond. J. Bot., 1844 A. obovata var. sparsifolia auct. angl. non (F. Zetterst.) Nyholm

(Fig. 28)

Autoicous. Usually small purple-red to black flattened spreading cushions, sometimes glaucous or green-black, rarely more than 1 cm high. Leaves often distant, erect-spreading, not clasping, sometimes secund when dry, spreading when moist, lanceolate, widest near base, gradually tapering to acute to obtuse apex; margins often incurved, entire; costa lacking; cells papillose from near base to apex, basal elongate, thick-walled, walls hardly pitted, not sinuose, an irregularly shaped yellowish patch of cells often present at leaf base, basal marginal cells isodiametric to oblate, transition to upper cells gradual, upper cells rounded or oval, thick-walled, ± pitted, papillose, 9–12 μm wide. Perigonia numerous, crimson. Perichaetial bracts larger than stem leaves, convolute. Spores 12–21(very rarely

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Fig. 28 1–4, Andreaea mutabilis: 1, leaves; 2, basal marginal cells; 3, basal cells; 4, upper cells. 5–8, A. sinuosa: 5, leaves; 6, leaf apex; 7, basal cells and axillary hairs. Leaves ×80, cells ×420. 5–7 modified from B. M. Murray, J. Bryol. 15, 17–82, 1988.

to 32) μm. Capsules common, summer. On dry to wet exposed acidic rocks, rarely on soil over rock. (60–)600–1300 m. Rare to occasional in N. Wales, northern England and the Scottish Highlands, extending north to Ross. 24. GB20 + 14∗ . Faeroes, Finland, France, Spain, British Columbia, widespread in the Southern Hemisphere. A. mutabilis is often recognisable by the small flattened cushions with numerous tiny crimson perigonia. It has leaves that are not or only very slightly sheathing, basal cells little pitted and esinuose, basal marginal cells that are isodiametric. There is often a marked central yellow patch at the base of leaves. It also has small spores. The leaves tend to be more distant in A. mutabilis than in other ecostate species so that the non-clasping leaf bases and insertions are often clearly visible. In the field A. mutabilis is likely to be mistaken for A. rupestris or A. alpestris but it tends to occur in very small flattened spreading cushions

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and to be purple-red (rarely glaucous from dense papillae). The report of A. obovata var. sparsifolia (F. Zetterst.) Nyholm from Britain is based on a misidentification. The collection is A. mutabilis.

5 A. sinuosa B. M. Murray, Bryologist, 1987 (Fig. 28) Apparently dioicous but possibly autoicous. Very small tufts or occasional stems in A. blyttii, green-brown, red-brown, purple-black or black, rarely more than 1 cm high. Leaves sometimes appearing tristichous when dry, slightly spreading when moist, narrowly lanceolate to linear-lanceolate, widest just above slightly sheathing base, apex acute or occasionally rounded; margins incurved, entire; costa lacking; basal cells rectangular to oblong, longitudinal walls incrassate, conspicuously pitted and strongly sinuose, basal marginal cells narrowly rectangular, transition to upper cells gradual, upper cells 10–12 μm wide, irregularly rounded, oval or oblate, with large low brown to colourless papillae that are more numerous centrally than marginally or apically. Perichaetial bracts larger than stem leaves, convolute. Capsules emergent to shortly exserted, base 1/2 or more length of capsule; spores (11−)13–19(−21) μm. Capsules common, summer. On acidic rock in extreme snow-beds or deep gullies with late snow-lie. 950–1100. Very rare, S. Aberdeen, Banff, E. Inverness, Ross. 5. GB5. Aleutian Islands, British Columbia. A. sinuosa can be distinguished from other ecostate Andreaea species by its strongly sinuose basal cell walls. It also has smaller spores than other species in the British Isles. In the field it can be confused with forms of A. rupestris var. rupestris with acuminate leaves that also occur at high altitudes. A. sinuosa, however, has less sheathing leaves with more strongly incurved margins.

¨ Section 2 Nerviae Cardot, Wiss. Erb. Schwed. Sudpolar-Exp., 1908 Leaves costate. 6 A. rothii F. Weber & D. Mohr, Bot. Taschenb., 1807 Autoicous, rarely synoicous. Brown to black cushions, sometimes coalescing and forming extensive mats, 0.5–2.5 cm high. Leaves erect to secund when dry, erectspreading to secund when moist, usually sharply contracted from ovate basal part to acute limb 2–5 times as long as basal part; margins entire or crenulate, rarely distantly toothed; costa percurrent to excurrent, filling upper limb, well defined, with occasional abaxial papillae, bulging abaxially, weaker towards base, about 1/ –1/ width of leaf base; basal cells of similar shape to upper cells, walls not pit6 3 ted, longer towards costa, marginal basal cells ± isodiametric, cells above mostly rounded to oblate, distinct or not, smooth or bulging, 8–12 μm wide. Perichaetial bracts larger than stem leaves, convolute. Spores (30−)36–52(−60–80) μm, occasionally aborted. Capsules common, spring, summer. Leaves usually weakly falcate, rarely brittle, cells usually distinct to near apex, costa usually percurrent or if excurrent filling up to 1/4 of apex, inner perichaetial bracts smooth or with very low sparse papillae ssp. rothii

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Leaves usually strongly falcate, brittle, costa usually filling 1/4 –1/2 upper part of leaf, cells rarely distinct to near apex, inner perichaetial bracts with dense high papillae above ssp. falcata Ssp. rothii (Fig. 29) Leaves erect to secund, rarely distinctly falcate when moist, rarely brittle; limb 2–3 times as long as basal part of leaf, cells distinct in limb; margins of limb entire or crenulate; costa usually percurrent, when excurrent filling only upper 1/4 of limb; cells usually distinct to near apex. Innermost perichaetial bracts usually with trace of costa, papillae lacking or very low and sparse. n = 10. On periodically moist acidic ± exposed rocks. 0–750 m. Rare in western and northern Britain and Ireland. 25, H11. GB26, IR15. Europe north to Fennoscandia, Iceland, Caucasus, Mongolia, N. America. Ssp. falcata (Schimp.) Lindb., Musci. Scand., 1879 (Fig. 29) A. crassinervia auct. non Bruch, A. crassinervia var. huntii (Lindb.) Braithw. Leaves usually strongly falcate when moist, brittle, limb 3–5 times as long as basal part, cells indistinct or sometimes distinct in limb; limb margins entire, crenulate or rarely distantly dentate; costa usually excurrent, occasionally percurrent, filling upper 1/4 –1/2 of limb; cells rarely distinct to near apex. Innermost perichaetial bracts usually ecostate; usually with dense sharp oblique papillae above, sometimes lacking in some plants in a population. n = 11∗ . On periodically moist acidic ± exposed rocks. 0–1344 m. Frequent to common in western and northern Britain, extending from Cornwall north to Shetland, frequent or common in W. Ireland, rare elsewhere. 66, H20. GB169, H36. Europe from Sardinia and Spain north to Sweden, Oregon. Ssp. rothii differs from ssp. falcata in its only slightly falcate and non-brittle leaves, in the lamina usually distinct almost to the apex, the costa only occasionally excurrent and the cells of the inner perichaetial leaves usually smooth. However, in the British Isles specimens of ssp. rothii frequently have somewhat falcate leaves, an excurrent costa and cells with scattered low papillae. It is possible that this intermediate form is the result of hybridisation between ssp. rothii and ssp. falcata. Typical material of ssp. falcata may be recognised by the black strongly falcate brittle leaves with long excurrent costa filling the upper limb and by the strongly papillose inner perichaetial bracts (although not necessarily in every perichaetium) – the papillae may be seen with a dissecting microscope. Ssp. falcata differs from A. crassinervia in its larger spores and its narrower abaxially bulging costa. Ssp. falcata is much commoner than ssp. rothii, constituting almost 90% of British and Irish gatherings named A. rothii and all gatherings named A. crassinervia. Ssp. rothii differs from A. frigida in the more abruptly formed limb, larger spores and its tendency to occur at lower elevations in drier sites. It has smaller spores than and lacks the dense perichaetial bract papillae of A. megistospora.

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Fig. 29 1–7, Andreaea rothii ssp. rothii: 1, 2, moist and dry shoot tips with sporophytes; 3, leaves; 4, basal marginal cells; 5, basal cells; 6, upper cells; 7, upper cells of inner perichaetial bract. 8–9, Andreaea rothii ssp. falcata: 8, leaves; 9, upper cells of inner perichaetial bract. Leaves ×65, cells ×420.

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A. crassinervia Bruch, Abh. Math-Phys. Cl. K¨onigl. Bayer. Akad. Wiss., 1832

Autoicous. Brown to black tufts, 0.5–2.5 cm high. Leaves erect to falcate-secund when dry, erect-spreading to secund when moist, ± abruptly tapering from an ovate basal part to acute limb 2–4 times as long as basal part; margins plane, entire; costa excurrent, filling almost entire limb, strong, poorly defined, often papillose abaxially, weaker towards base, usually 1/3 –1/2 width of leaf base; basal cells similar to upper, cells near costa with walls often sinuose, cells above indistinct and usually present only in lower 1/3 of limb, rounded, oval or oblate, smooth to bulging, 9–12 μm wide. Perichaetial bracts differentiated from stem leaves, sheathing, inner bracts ecostate, with or without scattered low rounded papillae, papillae rarely dense or sharp. Spores (20−)26–36(–50) μm. Usually montane. One specimen doubtfully collected at Dubh Loch, S. Aberdeen (possibly 1870). Europe, North America. A. crassinervia is easily recognized by the very wide poorly defined costa that fills almost the entire limb. It is distinguished from other species in which the costa fills a large part of the limb by its spores, which are larger than those of A. blyttii and smaller than those of A. rothii ssp. falcata. With one exception all British material previously identified as A. crassinervia was misidentified A. rothii ssp. falcata. There is one specimen labelled Dunloch in NY but careful search at the locality (Dubh Loch) failed to find A. crassinervia. Because of the poor labelling of the packet and the nature of its contents the specimen must be regarded as of doubtful provenance and the species excluded from the British list.

7 A. frigida Huebener, Hepaticol. Germ., 1834 A. rothii ssp. frigida (Huebener) Schultze-Motel

(Fig. 30)

Autoicous. Coarse red-maroon cushions, to over 4 cm high. Leaves erect, straight or often secund when moist, little changed when dry, ± lanceolate or gradually narrowed from ovate basal part to acute limb 1.5–2.0 times as long as basal part; margins entire; costa percurrent or rarely excurrent, filling upper 1/4 of limb, ± well defined, smooth, weaker towards leaf base, about 1/4 –1/3 width of leaf base; basal cells of similar shape to cells above, not pitted, cells near costa rectangular, usually with sinuose walls, upper cells distinct, rounded, oval or oblate, ± thin-walled, smooth to bulging, 8–12 μm wide. Perichaetial bracts differentiated from stem leaves, convolute, inner bracts partly costate, rarely ecostate, cells smooth. Spores (20−)25–35(−40) μm. Capsules common, summer. On acidic boulders or rock subject to periodic inundation in mountain streams and by lochs. (50−)660–1200 m. Very rare, N. W. Yorkshire (old record), Cumberland, S. Aberdeen, Banff. 4. GB4 + 1∗ . Europe from Romania and Portugal Norway, Iceland. Recognisable by the combination of gradually narrowed, lanceolate leaves with the cells distinct to the apex and spores (20−)25–35(−40) μm. Distinguished from A. rothii and A. megistospora by its large size and occurrence in wet montane habitats. A. frigida is regarded as vulnerable in the Red List of British Mosses.

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Fig. 30 1–3, Andreaea megistospora: 1, leaves; 2, basal cells; 3, upper cells. 4–7, A. frigida: 4, leaves; 5, basal marginal cells; 6, basal cells; 7, upper cells. Leaves ×90, cells ×420.

8 A. megistospora B. M. Murray, Bryologist, 1987 (Fig. 30) Autoicous. Brown to black small, rarely medium-sized plants, usually less than 1 cm high, rarely to 1.5 cm. Leaves appressed when dry, erect-spreading or secund when moist, often abruptly contracted from an ovate or oblong basal part to acute

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limb 2–3 times as long as basal part; margins plane, entire; costa strong, percurrent to excurrent, filling upper 1/4 of limb, well defined, with occasional abaxial papillae, biconvex or bulging abaxially, rarely weaker towards base, c. 1/6 –1/4 width of leaf base; basal cells similar to or slightly longer than upper, walls often sinuose, not pitted, cells distinct in limb, mostly rounded to oblate, thin-walled, smooth or bulging, 8–12 μm wide. Perichaetial bracts differentiated from stem leaves, convolute, inner bracts ecostate, usually with low rounded papillae, papillae rarely sharp and oblique. Spores very large (40−)50–90(−110) μm. Capsules common, spring, summer. On dry to moist, usually exposed acidic rock. 0–700(−1100) m. Rare, Pembroke, Merioneth, scattered localities in western Scotland from Kircudbright north to the Outer Hebrides, W. Cork, Sligo, old records from Durham, Westmorland, Mid Cork, Leitrim. 19, H4. GB16 + 11∗ , IR2 + 2∗ . N. W. Portugal, Norwegian coast north to 63◦ N, N. W. North America. A. megistospora is distinguished from all other Andreaea species by its very large spores. It is also recognisable by its relatively small size and leaves with the cells distinct to the apex. It is distinguished from A. rothii ssp. rothii and A. frigida, the other taxa in the British Isles with similar leaves, by its papillose perichaetial bracts. European material of A. megistospora belongs to ssp. megistospora; a second subspecies, ssp. papillosa B. M. Murray, occurs in N. W. North America.

9 A. blyttii Schimp. in Bruch et al., Bryol. Eur., 1855 (Fig. 31) Dioicous. Brown to black tufts or patches, often brown below and black above, 0.5– 2.5 cm high. Leaves erect to secund, brittle when dry, erect-spreading to secund or spreading when moist, ± abruptly narrowed from narrow oblong or ovate basal part to limb 3–4 times as long as basal part, limb narrow, often only two cells wide apically, uneven in outline, fragile; margins plane, entire; costa present, ± filling limb, weaker or occasionally absent basally, poorly defined, with occasional abaxial papillae, not bulging abaxially, c. 1/6 –1/3 width of leaf base; basal cells rectangular to shortly rectangular, in longitudinal rows, walls incrassate, hardly pitted, very rarely inconspicuously finely sinuose, basal marginal cells mostly shortly rectangular, upper cells indistinct in limb, rounded or quadrate, ± smooth to bulging, rarely with low papillae, (9−)10–12 μm wide. Perichaetial bracts differentiated from stem leaves, convolute, inner bracts ecostate, cells smooth or with low scattered papillae. Spores (11−)13–19(−23) μm. Capsules occasional, summer. On acidic rock slabs or boulders in scree by late snow-patches, usually on more or less perpendicular drier surfaces, snow-covered rocks or in melt-water early in summer, dry and exposed later on. c. 900–1200 m. Very rare, S. Aberdeen, Banff, Inverness, Ross. 6. GB8. Finland, France, Iceland, Norway, Poland, Spain, Svalbard, Sweden, N. Russia, N. America, Greenland. A. blyttii differs from other costate Andreaea species in its very narrow limb, the lamina often only two cells wide on either side of the costa above, basal cells mostly rectangular, costa often weak to absent in the base of the leaf, the spores small and it is dioicous.

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Fig. 31 1–2, Andreaea nivalis: 1, leaves (×40); 2, cells at widest part of leaf. 3–5, A. blyttii: 3, leaves (×80); 4, basal cells; 5, upper cells. Cells ×420. J. W. Heslop-Harrison & R. B. Cooke (J. Bot. Lond, 80, 35–38, 1942) reported A. blyttii and A. obovata Thed. (as A. hartmanii Thed.) as new to the British Isles but the records were not substantiated.

Subgenus 2. Chasmocalyx (Lindb. ex Braithw.) Limpr., Laubm. Deutschl., 1885 Stem epidermal cells very small. Leaf margins often incurved or recurved; leaf bases auriculate. Perichaetial bracts differentiated from stem leaves, sheathing or not. Pseudopodium formed from gametophyte stem as well as achegonial stalk. 10 A. nivalis Hook., Trans. Linn. Soc. Lond., 1811 (Fig. 31) Dioicous. Brownish green to red-brown tufts, patches or large mats, (1−)4– 6(−10) cm high. Leaves imbricate when dry, patent to spreading or falcate-secund when moist, narrowly lanceolate to ovate-lanceolate, gradually tapering from oblong basal part to acute apex, base somewhat decurrent or auriculate; margins irregularly denticulate or papillose-crenulate, sometimes partially recurved

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on one or both sides; costa reddish, subpercurrent or filling leaf apex, strongly papillose on abaxial side; basal cell walls not sinuose or pitted, cells in upper part of leaf distinct, coarsely papillose on both sides, quadrate to rounded, 8–11 μm wide. Perichaetial bracts similar to but a little larger than stem leaves, not convolute. Spores 24–33(−40) μm, occasional spores aborted. Capsules occasional, early summer. n = 10. On wet rocks at edges of streams and flushes that are usually fed by snow-beds, on seeping outcrops and ledges that are flat to gently sloping. (720−)880–1300 m. Rare but locally abundant in the Scottish Highlands. 10. GB15 + 4∗ . Montane Europe from Austria and Italy north to Fennoscandia, Caucasus, Siberia, Japan, North America, Greenland.

Class 3 Polytrichopsida

Acrocarpous. Plants frequently large, stems simple or branched, tough, with internal anatomical differentiation. Leaves often with broad costa bearing adaxial longitudinal lamellae. Setae long; capsules dehiscent; peristome nematodontous. The peristome teeth of members of the Polytrichales are not homologous with those of members of the Bryopsida or Tetraphidales which in turn are not homologous with those of the Bryopsidia.

3 Polytrichales Plants large, usually rhizomatous. Stems with central strand with differentiated conducting tissue. Leaves usually differentiated into sheathing base with narrow costa, and blade composed largely of expanded costa bearing longitudinal lamellae on adaxial side, lamina usually narrow, 1–2-stratose; margins toothed or entire, sometimes bordered. Capsules erect to horizontal, spherical to cylindrical, terete or 2–6-angled, hypophysis present or not; annulus absent; peristome nematodontous, with 32 or 64 teeth; columella expanded at top into membranous epiphragm joined to tips of peristome teeth; calyptrae cucullate, glabrous or hairy. A probably ancient group of one family and about 23 genera.

3 Polytrichaceae For a conspectus of the genera of the Polytrichaceae see G. L. Smith, Mem. New York Bot. Gard. 21(3), 1–82, 1971. Vegetative propagules unknown but many species readily regenerating from fragments of leaves and stems.

3 POGONATUM P. BEAUV., MAG. ENCYCL., 1804 Dioicous. Shoots arising from decumbent rhizome-like stems or from persistent protonemata. Leaves with broad sheathing basal part abruptly narrowed into lingulate to narrowly lanceolate blade consisting mainly of costa bearing numerous straight lamellae on adaxial side. Capsules erect, terete, without hypophysis or stomata, exothecial cells mamillose, not pitted; peristome teeth 32; calyptrae densely hairy, covering capsule. A cosmopolitan genus of 32 species.

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¨ For a homograph of Pogonatum see J. Hyvonen, Acta Bot. Fennica 138, 1–87, 1989. Derivation: bearded, referring to the hairy calyptrae.

Key to species of Pogonatum, Polytrichastrum and Polytrichum 1 Leaf margins entire, inflexed over blade 2 Leaf margins toothed, not inflexed over blade 5 2 Leaf apices cucullate, costae ending in apex or shortly excurrent, capsules obscurely angled 4. Polytrichastrum sexangulare (p. 125) Leaf apices not cucullate, costa excurrent in arista, capsules sharply angled 3 3 Costae excurrent in hyaline arista, smooth on abaxial side above, crenulae of lamellae directed towards leaf apex 2. Polytrichum piliferum (p. 129) Costa excurrent in brownish arista, toothed on abaxial side above, lamellae crenulae ± erect 4 4 Plants mostly 1–7 cm high, tomentum if present brownish, spores 8–10(–12) μm 3. Polytrichum juniperinum (p. 130) Plants mostly 6–20 cm high, stems with dense off-white tomentum below, spores (12–)14–18 μm 4. Polytrichum strictum (p. 130) 5 Plants to 2 cm high, unbranched, shoots arising from dark green persistent protonemata, capsules terete 6 Plants (1–)2–40 cm high, shoots sometimes branched, arising from prostrate rhizome-like stems, capsules terete or angled 7 6 Capsules ± spherical, exothecial cells finely papillose, leaf blades shortly oblong, bluntly pointed 1. Pogonatum nanum (p. 119) Capsules usually shortly cylindrical, exothecial cells coarsely mamillose, leaf blades lingulate to oblong-lanceolate, acute to obtuse 2. Pogonatum aloides (p. 120) 7 Apical cells of lamellae papillose, capsules terete 8 Apical cells of lamellae smooth, capsules angled 9 8 Leaves glaucous green, acute, lamellae 5–6 cells high with apical cells rounded or elliptical in section 3. Pogonatum urnigerum (p. 122) Leaves dull green, acuminate, lamellae 6–8(–9) cells high with apical cells strawberry-shaped in section 1. Polytrichastrum alpinum (p. 123) 9 Capsules obscurely angled, leaf lamina on each side of costa in mid-blade 6 or more cells wide, cells 14–25 μm wide 2. Polytrichastrum longisetum (p. 123) Capsules sharply 4–6-angled, lamina in mid-blade 1–5 cells wide, cells 10–16 μm wide 10 10 Apical cells of lamellae rounded in section, capsules rectangular, 4–6-angled 3. Polytrichastrum formosum (p. 125) Apical cells of lamellae grooved or flat-topped in section, capsules cubic to shortly rectangular, 4-angled 1. Polytrichum commune (p. 128)

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1 P. nanum (Schreb. ex Hedw.) P. Beauv., Prodr. Aeth´eogam., 1805 Polytrichum nanum Schreb. ex Hedw.

(Fig. 32)

Dark green patches or scattered plants, to 5(–10) mm high, arising from dark green persistent protonemal mat. Leaves crowded, erect when dry, erect-patent when moist, blade ± shortly oblong, bluntly pointed; margins bluntly toothed from about the middle of the blade, teeth mostly consisting of only 1 cell; lamellae 4–6(–10) cells high, apical cells smooth, rounded in section, not enlarged; costa percurrent. Setae deep red, flexuose, 0.5–3.0 cm long; capsules erect or inclined, spherical to ovoid, urceolate or turbinate when dry and empty; exothecial cells finely papillose; peristome teeth 320–400 μm long; lid rostellate; columella cylindrical; spores 24–27 μm. Capsules common, winter. n = 7. On acidic soil on banks, heaths and roadsides. 0–550 m. Occasional but not seen recently in many vicecounties throughout Britain and Ireland. 97, H19, C. GB210 + 139∗ , IR 10 + 12∗ , C3. European Temperate. Europe, Faeroes, Iceland, Macaronesia, N. Africa. P. nanum cannot be distinguished from small forms of P. aloides when capsules are lacking. Possibly overlooked as there has been confusion with P. aloides (q.v.). P. nanum seems to have decreased considerably in central and eastern England.

2 P. aloides (Hedw.) P. Beauv., Prodr. Aeth´eogam., 1805 Polytrichum aloides Hedw.

(Fig. 32)

Dark green scattered shoots or lax patches, to about 2 cm high, arising from persistent protonemal mat. Leaves crowded, erect when dry, erect-patent to spreading when moist, blade lingulate to oblong-lanceolate, obtuse to acute; margins plane or erect, toothed from base of blade to apex, teeth of 2 to several cells but in small forms unicellular and only from about mid-blade; lamellae 40–60, 5–6 cells high, apical cells smooth, in section rounded, not enlarged; costa ending in apex to slightly excurrent. Setae deep red, 1–4 cm long; capsules erect or slightly inclined, shortly cylindrical to ovoid or obovoid, frequently slightly asymmetrical or urceolate when dry and empty, exothecial cells conically mamillose; peristome teeth 150–200 μm long; columella 4-winged; spores 8–13 μm. Capsules common, autumn, winter. n = 7∗ , 14. On sheltered disturbed acid, peaty or mineral soil by roads, on banks, sides of ditches, in woods, often on vertical or sloping substrates. 0–400(–600) m. Frequent or common except in basic habitats. 110, H37, C. GB1230 + 117∗ , IR196 + 10∗ , C9. European Boreo-temperate. Throughout most of Europe, Faeroes, Caucasus, Turkey, Macaronesia, New Zealand (introduced). Depauperate forms of P. aloides cannot be distinguished from P. nanum when sterile but normal plants have more acutely pointed leaves with marginal teeth, composed of 2 to several cells, from base to apex of the blade. The capsules of P. aloides also differ in shape except in stunted forms which may be distinguished from P. nanum by the coarsely mamillose exothecial cells (easily seen at the edge of a flattened capsule), shorter peristome teeth and larger spores. Both species differ from P. urnigerum and Polytrichastrum and Polytrichum species

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Fig. 32 1–6, Pogonatum nanum: 1, shoot; 2, leaves; 3, leaf margin towards apex; 4, part of lamella in side view; 5, section of lamella; 6, capsule (×10). 7–12, P. aloides: 7, shoot; 8, leaves; 9, leaf margin towards apex; 10, part of lamella in side view; 11, section of lamella; 12, capsule (×10). 13–18, P. urnigerum: 13, shoot; 14, leaf; 15, part of lamella in side view; 16, section of lamella; 17, capsule with calyptra (×7.5); 18, capsule (×7.5). Plants ×1, leaves ×7.5, cells ×450.

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in the shoots arising from persistent protonemata instead of from prostrate rhizome-like stems. ¨ J. Hyvonen (loc. cit.) in his monograph treats P. aloides var. minimum (Crome) Molendo, as a synonym of the type.

3 P. urnigerum (Hedw.) P. Beauv., Prodr. Aeth´eogam., 1805 Polytrichum urnigerum Hedw.

(Fig. 32)

Glaucous green patches or scattered plants, to 7(–10) cm high. Shoots arising from prostrate rhizome-like stems; protonemata not persisting. Leaves erect when dry, patent to spreading when moist, blade lanceolate to narrowly lanceolate, acute; margins with coarse spinose teeth; lamellae 30–50, mostly 5–6 cells high, apical cells papillose, incrassate, in section enlarged, rounded or elliptical; costa excurrent. Setae 1–3(–5) cm; capsules shortly cylindrical, ± erect to inclined; exothecial cells coarsely mamillose; spores 10–14 μm. Capsules common, autumn, winter. n = 7∗ , 14. On acidic, well drained, disturbed, often sandy or gravelly soil on banks, amongst rocks, in turf, on wall tops, roadsides. 0–1330 m. Rare to occasional in lowland England, frequent to common elsewhere. 105, H34, C. GB880 + 82∗ , IR143 + 4∗ , C1. Circumpolar Boreo-arctic Montane. Throughout Europe north to Svalbard, Faeroes, Iceland, Caucasus, Asia, New Guinea, Macaronesia, N. America, Greenland, Caribbean. Although usually distinct from Polytrichastrum alpinum in its glaucous green colour, taller forms on damp ground may lack the glaucous tint but differ in the relatively shorter broader leaf blades, the shorter lamellae with apical cells rounded or elliptical in section and the ± erect capsules with coarsely mamillose exothecial cells. Vegetative propagation by caducous leaves may sometimes occur. Although not reported in the literature the apical cells of the lamellae are very rarely completely smooth.

4 POLYTRICHASTRUM G. L. Sm., MEM. NEW YORK BOT. GARD., 1971 Dioicous. Protonemata ephemeral. Shoots arising from prostrate rhizome-like stems. Leaves with broad sheathing basal part abruptly narrowed into erect-patent to spreading lanceolate to linear-lanceolate blade composed mainly of costa with very narrow lamina on either side; costa with numerous ± straight lamellae on the adaxial side. Capsules inclined to horizontal, terete or obscurely or sharply 4–6-angled, hypophysis weakly or well differentiated, stomata present; exothecial cells smooth, not pitted; peristome teeth 64 (c. 45 in P. alpinum as a result of fusion), without appendages or wings on the inner face (leiodont); epiphragm fleshy, dorsal margins entire or with tooth-like projections adhering to the inner surface of the peristome teeth, ventral margins entire, annulus-like structure present on the under surface; calyptrae densely hairy, covering capsules. About 13 species world-wide. Derivation: incomplete similarity to Polytrichum.

For key to species of Polytrichastrum see under Pogonatum (p. 118).

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123

Section 1 Polytrichastrum Leaf margins toothed, not inflexed; apical cells of lamellae papillose, not pyriform in section. Capsules terete, hypophysis obscure, exothecial cells smooth, not pitted; peristome teeth variable in number because of fusion. 1 P. alpinum (Hedw.) G. L. Sm., Mem. New York Bot. Gard., 1971 ¨ Pogonatum alpinum (Hedw.) Rohl., Polytrichum alpinum Hedw.

(Fig. 33)

Lax dull green tufts, tall turfs or patches, to c. 10 cm high. Leaves erect-inflexed when dry, erect-patent to recurved when moist, blade linear-lanceolate, acuminate; margins toothed; lamellae 30–40, 5–9 cells high, apical cells incrassate, papillose, enlarged and strawberry-shaped in section; costa excurrent. Setae flexuose, yellowish above, reddish below, 0.5–3.0 cm long; capsules suberect to inclined, asymmetrical, subglobose to subcylindrical, terete, rugose but not angled when dry, exothecial cells smooth, not pitted, stomata present at base of poorly defined hypophysis; lid with long curved beak; peristome teeth c. 45, irregular, short; spores 18–20 μm. Capsules common, autumn. n = 7∗ , 14. On stony banks, amongst rocks, on cliff ledges and moorland peat, in montane areas. 0–915 m. Absent from lowland England, occasional to common elsewhere, occasional in N. W. Ireland, very rare elsewhere. 68, H22. GB341 + 53∗ , IR39 + 8∗ . Circumpolar Boreo-arctic Montane. Europe north to Svalbard, Faeroes, Iceland, Caucasus, Turkey, N., C. and E. Asia, Kerguelen Is., N. America, Greenland, Mexico, southern S. America, Antarctica. A very variable species both in size of the gametophyte and shape of the capsules. The plant named var. septentrionale (Sw.) Lindb., about 2 cm tall with very short setae and ± globose capsules, appears to be an extreme form not worthy of taxonomic recognition (see A. Schreibl, Carinthia (Klagenfurt) 181/101, 461–506, 1991). P. alpinum differs from other Polytrichastrum and from Polytrichum species in the terete capsules and the papillose marginal cells of the leaf lamellae. For the differences from Pogonatum urnigerum see under that plant.

Section 2 Sexangularia (Bruch & Schimp.) G. L. Sm., Mem. New York Bot. Gard., 1971 Leaf margins toothed, if inflexed not greatly broadened; apical cells of lamellae smooth, not pyriform in section. Capsules sharply or obscurely angled, hypophysis poorly or well defined, exothecial cells smooth, not pitted; peristome teeth 64. 2 P. longisetum (Sw. ex Brid.) G. L. Sm., Mem. New York Bot. Gard., 1971 (Fig. 33) Polytrichum aurantiacum Brid., Polytrichum gracile Metnz., Polytrichum longisetum Sw. ex Brid. Dark green tufts or turfs, 1.5–10.0 cm high. Leaves ± erect, flexuose when dry, spreading, recurved when moist, blade narrowly lanceolate, acuminate; margins erect, toothed, lamellae usually 25–35, 5–7 cells high, apical cells smooth, incrassate, in section hardly enlarged; costa excurrent in denticulate brown arista;

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Fig. 33 1–7, Polytrichastrum alpinum: 1, shoot; 2, leaf; 3, part of lamella in side view; 4, section of lamella; 5. capsule. 6–7, Plant referred to as P. alpinum var. septentrionale: 6, plant 7, capsule. 8–14, P. longisetum: 8, shoot; 9, leaf; 10, part of lamella in side view; 11, section of lamella; 12, marginal cells of leaf blade; 13, 14, moist and dry capsules. Shoots ×1, leaves ×7, capsules ×5, cells ×450.

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125

lamina at middle of blade 6 or more cells wide, cells 16–20(–25) μm wide. Setae flexuose, reddish brown below, yellowish above, 1.5–6.0 cm long; capsules erect at maturity, inclined with age, obloid, obscurely 5–6-angled; hypophysis well defined; lid with long beak; spores 20–26 μm. Capsules common, summer. n = 7∗ , 14. On well drained acidic soil on heaths and moorland and in woods. 0–1030 m. Generally distributed, occasional. 92, H31. GB261 + 78∗ , IR26 + 20∗ . Circumpolar Boreo-temperate. Europe north to Svalbard, Faeroes, Iceland, Caucasus, Turkey, N. Asia, Korea, Japan, New Guinea, N. America, Greenland, Chile, New Zealand. This plant has been confused in the past with P. formosum as one of the key characters given in Dixon & Jameson (1924), the length of the cells in the sheathing leaf base, is unreliable. Fertile material differs from other Polytrichastrum and from Polytrichum species except Polytrichastrum sexangulare in the obscurely angled capsules. When sterile it differs in the wider laminae with larger cells and the costa with fewer lamellae.

3 P. formosum (Hedw.) G. L. Sm., Mem. New York Bot. Gard., 1971 Polytrichum formosum Hedw.

(Fig. 34)

Dark green tufts or turfs, to 10(–20) cm high. Leaves erect-flexuose when dry, spreading to recurved when moist, sheathing base not glossy, blade narrowly lanceolate, acuminate; margins plane or erect, toothed; lamellae to 70, 5–7 cells high, apical cells smooth, incrassate, in section rounded, not or scarcely enlarged; costa excurrent in denticulate arista; lamina in mid-blade 2–5 cells wide, cells 10–14(–16) μm wide. Setae flexuose, yellowish above, reddish below, 2.5–6.0 cm long; capsules erect or inclined, rectangular, sharply (4–)6-angled, hypophysis distinct; lid longly rostrate; spores 12–16 μm. Capsules frequent, summer. n = 7∗ , 14. On usually acidic soils on heaths, moorland, in woods, on rocks, cliff ledges, crevices in scree and old walls. 0–500 m. Frequent to common and sometimes locally abundant in suitable habitats. 112, H39, C. GB1527 + 75∗ , IR236 + 3∗ , C6. Circumpolar Boreo-temperate. Europe, Faeroes, Iceland, Caucasus, Turkey, Asia, New Guinea, Macaronesia, Algeria, southern Africa, N. America, Greenland, New Zealand. Typical forms of Polytrichum commune are larger than P. formosum with more distant leaves with shiny bases. However, forms of Polytrichum commune from drier habitats such as rock ledges and woodland may be much smaller and resemble plants of P. formosum but have shorter, consistently 4-angled capsules. In the absence of capsules, sections of the lamellae are necessary for identification.

¨ 4 P. sexangulare (Florke ex Brid.) G. L. Sm., Mem. New York Bot. Gard., 1971 (Fig. 35) ¨ Polytrichum norvegicum auct. non Hedw., Polytrichum sexangulare Florke ex Brid. Dark green patches, shoots erect or decumbent, 1–10 cm long. Leaves rigid, imbricate, incurved at the tips when dry, patent when moist, narrowly to broadly

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Fig. 34 1–7, Polytrichum commune var. commune: 1, shoot; 2, leaf (×5) and 3, perichaetial leaf (×5); 4, section of lamella; 5, part of lamella in side view; 6, 7, dry and moist capsules. 8–9, P. commune var. perigoniale: 8, perichaetial leaf (×7); 9, section of lamella. 10, P. commune var. humile: perichaetial leaf (×7). 11–17, Polytrichastrum formosum: 11, shoot; 12, leaf (×5); 13, section of lamella; 14, marginal cells of leaf blade; 15, part of lamella in side view; 16, 17, moist and dry capsules. Shoots ×1, capsules ×5, cells ×450.

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127

Fig. 35 1–4, Polytrichum juniperinum: 1, shoot; 2, leaf; 3, section of lamella; 4, part of lamella in side view. 5–8, Polytrichum piliferum: 5, shoot; 6, leaf; 7, section of lamella; 8, part of lamella in side view. 9–12, Polytrichastrum sexangulare: 9, shoot; 10, leaf; 11, section of lamella; 12, part of lamella in side view. 13–16, Polytrichum strictum: 13, shoot; 14, leaf; 15, section of lamella; 16, part of lamella in side view. Shoots ×1, leaves ×7, cells ×450.

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ligulate, apex broad to acute, cucullate; margins entire, erect below, incurved above; lamellae 30–35, 5–7 cells high, apical cells smooth, incrassate, in section rounded to conical, not or scarcely enlarged; costa ending in apex to shortly excurrent. Setae 2–3 cm long, stout; capsules erect or inclined, obloid, bluntly 6-angled, hypophysis hardly distinct; lid with long beak; spores 18–20 μm. Capsules occasional, summer. n = 14. On soil, often in areas of late snow-lie in the Scottish Highlands. 900–1325 m. Very rare, Perth, Aberdeen, Banff, Inverness, Ross. 9. GB21 + 1∗ . European Arctic-montane. Europe, from Pyrenees, Alps and Greece north to Svalbard, Faeroes, Iceland, Caucasus, Siberia, Japan, N. America, Greenland.

5 POLYTRICHUM HEDW., SP. MUSC. FROND., 1801 Gametophytes indistinguishable from those of Polytrichastrum. Capsules erect to horizontal, sharply 4–6-angled, hypophysis distinct, stomata present; exothecial cells bulging or mamillose, walls pitted; peristome teeth 64, each with vertical partitions and spur-like appendages on the inner face (pterygodont); epiphragm membranous with sac-like lobes on ventral margin alternating with peristome teeth; calyptrae densely hairy, covering capsules. A cosmopolitan genus of some 100 mainly calcifuge species. Derivation: many hairs, referring to the calyptrae.

For a key to Polytrichum species see under Pogonatum (p. 118). Section 1 Polytrichum Leaf margins toothed, not inflexed; apical cells of lamellae smooth, not pyriform in section. 1 P. commune Hedw., Sp. Musc. Frond. Frond., 1801 Plants 2–40 cm. Leaves flexuose when dry, spreading to squarrose when moist, leaf sheath glossy, blade narrowly lanceolate, acuminate; margins toothed; lamellae to c. 70, 5–9 cells high, apical cells smooth, in section enlarged, grooved or flat-topped; costa excurrent in denticulate point; lamina at mid-blade 1–3 cells wide, cells 10– 16 μm wide. Perichaetial leaves with long sheathing base gradually or abruptly narrowed into acuminate apex. Setae flexuose, reddish, 5–9 cm long; capsules erect at maturity, becoming inclined with age, cubic to shortly rectangular, sharply 4-angled, slightly trapezoid in section, hypophysis very distinct; spores 8–12 μm. Capsules frequent, summer. 1 Plants (2–)5–40 cm high, apical cells of lamellae in section 16–20 μm wide, grooved, inner perichaetial leaves toothed above var. commune Plants to 6 cm high, apical cells of lamellae 10–14 μm wide, in section flat-topped or hardly grooved, inner perichaetial leaves entire or only slightly toothed above 2

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129

2 Inner perichaetial leaves gradually tapering to long acuminate apex var. perigoniale Inner perichaetial leaves abruptly narrowed from sheathing base to short acuminate apex var. humile Var. commune (Fig. 34) Dark green tufts or turfs, sometimes of considerable size, (2–)5–40 cm high. Leaf margins sharply toothed; apical cells of lamellae in section 16–20 μm wide, grooved but towards base of blade less deeply grooved or flat-topped. Inner perichaetial leaves longly tapering, denticulate towards apex. Capsules cubic to shortly rectangular. n = 7∗ , 14. In bogs, by streams, on wet heaths, Racomitrium heath and in woodland. 0–1050 m. Frequent to common and sometimes abundant in suitable habitats. 112, H37, C. GB1416 + 112∗ , IR227 + 7∗ , C1 + 1∗ . Circumpolar Wideboreal. Europe, Faeroes, Iceland, Caucasus, N. and E. Asia, Macaronesia, Africa, N. America, Greenland, Peru, Brazil, Australasia, Chatham Is. Var. perigoniale (Michx.) Hampe, Linnaea, 1819 P. perigoniale Michx.

(Fig. 34)

Plants to c. 6 cm high. Leaves less sharply toothed than in var. commune; apical cells of lamellae less deeply grooved or flat-topped, 10–14 μm wide in section. Perichaetial leaves tapering to entire or slightly toothed acuminate apex. Capsules cubic. On soil and rock ledges in drier habitats than var. commune. Rare, scattered localities from S. Devon and Hampshire north to Ross and Orkney. 25. Europe, Madeira, N. Africa, N. America, Australia. Var. humile Sw., Adnat. Bot., 1829 P. commune var. minus De Not.

(Fig. 34)

Similar to var. perigoniale but perichaetial leaves abruptly narrowed from sheathing base into short acuminate apex. Similar habitats to var. perigoniale. Rare; and not seen recently, extending from W. Cornwall and E. Sussex north to Angus and E. Inverness, Down. 20, H1. Central Europe, Morocco, Macaronesia. P. commune may occur in open woodland on extremely acid soil where it may be mistaken for Polytrichastrum formosum (q.v.). A. Schriebl (Carinthia/Klagenfurt 181/101, 461– 506, 1991) suggests on the basis of cultivation experiments that var. perigoniale should be raised to specific status but he does not present any convincing evidence in support of this. He makes no mention of var. humile. P. swartzii Hartm. has been reported from Britain but the determinations are incorrect (see A. C. Crundwell, Trans. Br. Bryol. Soc. 3, 174–9, 1957).

Section 2 Juniperifolia Brid., Musc. Rec., Suppl., 1806 Leaf margins entire, greatly broadened and inflexed above; apical cells of lamellae smooth, in section pyriform.

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2 P. piliferum Hedw., Sp. Musc. Frond., 1801 (Fig. 35) Green to brownish green patches, (0.5–)1.0–6.0 cm high. Leaves crowded towards stem apex, 2–3 mm long, appressed, straight when dry, patent when moist, blade narrowly lanceolate, acute to acuminate, smooth on abaxial side; margins entire, inflexed and overlapping in upper half or more of blade; lamellae 30–35(–40), 4–8 cells high, crenulate with crenulae directed towards leaf apex, apical cells smooth, cruciform in section at least in middle of blade; costa excurrent in hyaline point up to 1 mm long. Perigonia intense red. Setae 1.5–3.0 cm long, red; capsules inclined, obloid, sharply 4(–6)-angled, hypophysis well defined; lid rostrate; spores 12–15 μm. Capsules common, summer. n = 7∗ , 14, 21. On exposed well drained sandy or gravelly soil or thin peat on heaths, roadsides, boulders, walls, in scree and open woodland, calcifuge. 0–1170 m. Frequent to common throughout the British Isles. 112, H34, C. GB1296 + 101∗ , IR151 + 1∗ , C7 + 3∗ . Circumpolar Wideboreal. More or less cosmopolitan. Usually readily separated from P. juniperinum by the hyaline hair-points of the leaves but forms with hair-points poorly developed or lacking may be determined from lamella characters. For information about the two species see S. R. Edwards, Bull. Br. Bryol. Soc. 65, 49–50, 1995.

3 P. juniperinum Hedw., Sp. Musc. Frond., 1801 (Fig. 35) Grey-green to dark green patches, 1–7(–10) cm high. Stems without or with sparse brown tomentum below. Leaves ± uniformly arranged up stem, 3–5 mm long, appressed, straight or with apiculus slightly flexuose when dry, patent when moist; blade narrowly lanceolate to linear-lanceolate, acute to acuminate, occasionally obtuse, toothed on abaxial side above; margins entire, inflexed but overlapping only towards apex; lamellae (30–)35–50(–70), 5–8 cells high, crenulate, crenulae not directed towards blade apex, apical cells sometimes minutely papillose, ± pyriform in section; costa excurrent in short brown point. Perigonia yellow-olive to orange-red. Perichaetial leaves sometimes with white hair-points. Setae 3–5 cm long, red; capsules erect or suberect, rectangular, sharply 4(–6)-angled, 2.25–4.00 mm long excluding lid, 1.5–2.4 times as long as wide, hypophysis well defined; spores 8–10(–12) μm. Capsules common, summer. n = 7∗ , 14. On exposed well drained soil on roadsides, wall tops, boulders, heaths, moorland, waste ground, open woodland, calcifuge. 0–300(–800) m. Common and sometimes locally abundant. 112, H38, C. GB1596 + 101∗ , IR238 + 10∗ , C8 + 2∗ . Circumpolar Wide-boreal. Temperate and cooler parts of the world. 4 P. strictum Brid., J. Bot. (Schrader), 1801 ¨ P. alpestre Hoppe, P. juniperinum ssp. strictum (Brid.) Nyl. & Sal.

(Fig. 35)

Dense matted dark green tufts, (3–)6–20 cm high. Stems slender, densely tomentose below with off-white tomentum. Leaves imbricate when dry, patent when

6 Oligotrichum

131

moist, blade narrowly lanceolate, acuminate, toothed on abaxial side above; margins entire, inflexed but overlapping only towards apex; lamellae 25–40, 5–6 cells high, crenulate to serrulate, apical cells incrassate, smooth, ± pyriform in section; costa excurrent in brownish arista. Setae slender, 3–4 cm long, red; capsules shortly rectangular, sharply 4-angled, 1.75–3.50 mm long excluding lid, 1.3–2.0 times as long as wide, hypophysis well defined; spores (12–)14–18 μm. Capsules occasional, summer. n = 7∗ . In bogs and on blanket peat, calcifuge. 0–1080 m. Common in suitable habitats in western and northern Britain, very rare and decreasing elsewhere. 80, H28. GB409 + 47∗ , IR70 + 5∗ . Circumpolar Boreo-arctic Montane. Europe north to Svalbard, Faeroes, Iceland, Caucasus, Turkey, N., C. and E. Asia, N. Africa, N. America, Greenland, Patagonia, Antarctica. The taxonomic status of this plant is open to question and various authorities treat it as a synonym, variety or subspecies of P. juniperinum. Occasional plants are encountered that are intermediate in form and cannot be named but the capsule is usually shorter and the spores larger than in P. juniperinum and additionally the dirty white tomentum of P. strictum distinguishes it from Polytrichastrum and other large Polytrichum species.

6 OLIGOTRICHUM LAM. & DC., FL. FRANC¸., 1805 Dioicous. Leaves broadly lanceolate to lingulate, gradually tapering from broad base, concave; margins not bordered; costa broad with tall sinuose longitudinal lamellae on adaxial side and a few longitudinal lamellae on abaxial side; lamina 1–2-stratose. Capsules ovoid to subcylindrical, lacking hypophysis, stomata present at base; peristome teeth 32; calyptrae sparsely hairy. A ± world-wide genus of about 25 species. Derivation: few hairs, referring to the sparsely hairy calyptrae.

1 O. hercynicum (Hedw.) Lam. & DC., Fl. Franc¸., 1805 (Fig. 36) Yellowish green to dark green or reddish brown scattered plants or lax patches, 0.5–4.0(–9.0) cm high. Stems rigid. Leaves incurved to crisped when dry, erectpatent, ± incurved when moist, narrowly triangular to lanceolate from broad base, apex cucullate, obtuse to acute; margins plane and obscurely toothed below, erect and bluntly toothed above; costa with c. 12 lamellae on adaxial side in upper 2 /3 of leaf, lamellae sinuose, to 12 cells high; margins notched and crenulate; on abaxial side of costa 2–4 widely spaced lamellae, 1–3 cells high; costa stout, ending in apex. Setae yellow, 1.5–3.5 cm long; capsules erect or slightly inclined, shortly cylindrical; lid rostrate; spores 12–15 μm. Capsules occasional, late summer. n = 7. On loose or gravelly acidic soil in western and northern Britain. 0–1330 μm. Frequent to common in submontane and montane areas, rare at low altitudes. 69, H18. GB438 + 37∗ , IR51 + 4∗ . Circumpolar Boreo-arctic Montane. Europe, Faeroes, Iceland, Turkey, Siberia, Japan, N. America, Greenland.

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Fig. 36 1–5, Oligotrichum hercynicum: 1, plant; 2, leaves (×15); 3, leaf section; 4, part of lamella in side view; 5, capsule (×7.5). 6–11, Atrichum undulatum var. undulatum: 6, plant; 7, leaf (×7.5); 8, part of leaf in side view (×15); 9, section of upper part of costa; 10, mid-leaf cells; 11, capsule (×5). 12–14, plant referred to as A. undulatum ‘var. minus’: 12, plant; 13, 14, capsules from different specimens (×5). Plants ×1, sections ×180, cells ×450.

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7 ATRICHUM P. BEAUV., MAG. ENCYCL., 1805 Autoicous or dioicous. Leaves narrowly lingulate to ovate, crisped when dry, sometimes undulate when moist, lamina often toothed on abaxial side above; margins with 1–3-stratose border of elongate narrow cells, toothed, teeth single or double; costa toothed on abaxial side above, with 2–9 lamellae 1–9 cells high on adaxial side in upper half of leaf. Capsules ovoid to cylindrical, straight to arcuate, erect or inclined; lid longly rostrate; peristome with 32 teeth; calyptrae glabrous. About 15 mainly temperate species. Derivation: hairless, with reference to the glabrous calyptrae. For a monograph of the genus see E. Nyholm, Lindbergia 1, 1–33, 1971. For an account of rhizoidal gemmae in Atrichum see T. Arts, Lindbergia 13, 72–74, 1987.

1 Leaves with 4–7 lamellae, cells in mid-leaf 12–18(–20) μm wide, spores 12–14 μm 4. A. angustatum Leaves with 1–6 lamellae, mid-leaf cells 30–50 μm wide, spores 16–20 μm 2 2 Leaves strongly undulate when moist, lingulate-lanceolate to narrowly lanceolate, not or scarcely narrowed towards base 3. A. undulatum Leaves not or only slightly undulate when moist, ± ovate to lanceolate, narrowed towards base 3 3 Leaves with 1–2(–4) obscure lamellae 1–3 cells high, mid-leaf cells 24–50 μm wide 1. A. crispum Leaves with 2–4(–5) lamellae (5–)6–9 cells high, mid-leaf cells 20–30(–40) μm wide 2. A. tenellum 1 A. crispum (Hampe) Sull. & Lesq., Musci Bor.-Amer., 1856 Catharinea crispa Hampe

(Fig. 37)

Dioicous. Pale green to green tufts or patches, (0.5–)1.0–7.0 cm high. Leaves crisped when dry, soft, patent, not or scarcely undulate when moist, ovate or oblong to oblong-lanceolate, sometimes obovate or oblanceolate, acute, narrowed at base, lamina without teeth on abaxial side; margins toothed almost from base, teeth single or occasionally double; lamellae 1–3(–4) in upper half of leaf, 1–3 cells high, often obscure; costa ending below apex; cells irregularly quadrate to ± hexagonal, obscurely papillose, 24–50 μm wide in midleaf, smaller towards margins, longer towards base. Gemmae usually present on rhizoid wicks, whitish to light brown, ± spherical, (50–)130–300 μm in diameter. Only male plants known in the British Isles. n = 7. On acidic sandy or gravelly soil or peat by ditches, streams, rivers and lakes, particularly in moorland habitats. 0–450 m. Frequent and sometimes locally abundant in Wales and parts of N. W. England, rare or occasional in S. W. England, Surrey, I. of Man, Wicklow, Leitrim. 27, H2. GB120 + 21∗ , IR3. Introduced (Suboceanic

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Fig. 37 1–3, Atrichum crispum: 1, leaves; 2, mid-leaf cells; 3, section of upper part of leaf. 4–7, A. tenellum: 4, leaves; 5, mid-leaf cells; 6, section of upper part of leaf; 7, capsule. 8–11, A. angustatum: 8, leaves; 9, mid-leaf cells; 10, section of upper part of leaf; 11, capsule. Leaves ×10, sections ×250, cells ×450, capsules ×7.5.

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Boreal-montane). Spain, eastern N. America (records from Belgium and Luxembourg are erroneous). Differs from other species of Atrichum in leaf shape, the very low lamellae and the absence of teeth on the abaxial side of the leaf. Because of the obscure lamellae the plant may be mistaken for a species of the Mniaceae but it differs in the frequent presence of gemmae and the albeit obscure lamellae. The earliest British record of this plant is from Rochdale, Lancashire, by John Nowell in 1848. It is clearly an introduction from N. America as until recently it was unknown elsewhere in Europe and only male plants occur. It is likely that the plants in the British Isles are a single clone, having spread by fragments and/or gemmae.

¨ 2 A. tenellum (Rohl.) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1844. (Fig. 37) ¨ Catharinea tenella Rohl. Dioicous. Dull green lax tufts or patches, to c. 1.5 cm high. Leaves crisped when dry, soft, erect-patent, not or scarcely undulate when moist, ovate or lanceolate, narrowed towards insertion, obtuse in lower leaves, acute to acuminate in upper, lamina with a few scattered teeth on abaxial side above; margins with single or double spinose teeth from about the middle; lamellae 2–4(–5), (3–)6–9 cells high; costa ending in apex; cells ± quadrate to irregularly hexagonal, 20–30(–40) μm wide in mid-leaf, smaller towards margins, longer towards base. Gemmae usually present on rhizoid wicks, pale brown to brown, ± spherical to irregular in shape, 130–400 μm diameter. Setae yellowish to reddish; capsules inclined, shortly cylindrical, straight or curved; spores 20–25 μm. Capsules rare, late summer to winter. n = 7, 14. On disturbed acidic soil in open habitats in woodland and by tracks. Lowland. Rare in S. E. England, very rare elsewhere, extending from W. Cornwall north to Ross, S. Kerry, W. Cork, W. Galway, W. Donegal. 23, H4. GB30 + 6∗ , IR1. Circumpolar Boreo-temperate. Italy and Yugoslavia north to Fennoscandia, Faeroes, Iceland, Caucasus, Turkey, Siberia, Japan, N. America. The gemmae described above have not been seen in British material but according to T. Arts they are always present if sufficient substrate is collected. It may be confused with small forms of A. undulatum but differs in the relatively wider, scarcely undulate leaves with only a few scattered teeth on the abaxial side, the fewer taller lamellae and the presence of rhizoidal gemmae.

3 A. undulatum (Hedw.) P. Beauv., Prodr. Aeth´eogam., 1805 Catharinea undulata (Hedw.) F. Weber & D. Mohr Yellowish green to green lax tufts or patches, sometimes extensive, or scattered plants, to 7 cm high. Leaves crisped when dry, soft, patent and strongly undulate when moist, narrowly lingulate to narrowly lanceolate, acuminate, not narrowed towards insertion, lamina with rows of teeth on abaxial side above; margins spinosely dentate with single or double teeth from near base; lamellae 3–6,

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3–7 cells high; costa ending in apex; cells irregularly hexagonal, incrassate, 20– 40 μm wide in mid-leaf, smaller towards margins, longer and more thin-walled towards base. Capsules inclined, cylindrical, arcuate; spores 16–20(–28) μm. Capsules common, winter. Circumpolar Boreo-temperate. Setae reddish, capsules curved, plants usually autoicous, very common var. undulatum Setae yellowish, capsules straight or slightly curved, plants paroicous, very rare var. gracilisetum Var. undulatum (Fig. 36) Usually autoicous, rarely apparently dioicous. Setae red, 1.5–3.0 cm long, frequently 2 or more per perichaetium; capsules curved. n = 7∗ , 14∗ , 21∗ . On disturbed soil in woods, on banks, heaths, damp grassland, by ditches and rivers. 0–600 m. Common and sometimes locally abundant. 112, H39, C. GB1880 + 76∗ , IR272 + 7∗ , C3 + 1∗ . Circumpolar Boreo-temperate. Throughout Europe, Faeroes, Iceland, Caucasus, Asia, Macaronesia, Algeria, Morocco, Canada, Mexico, C. America. Var. gracilisetum Besch., Ann. Sci. Nat. Bot., 1883 A. undulatum var. haussknechtii (Jur. & Milde) Frye Paroicous. Antheridia terminal, archegonia outside perigonial leaves; stems continuing growth for 2 or more years so that persistent setae appear lateral. Setae yellow, to 2 cm long, often several per perichaetium; capsules straight or slightly curved. n = 7, 14, 21. Similar habitats to the type but very rare and not seen for more than 70 years. Surrey, Warwick, Shropshire, S. Lancashire. 4. Throughout Europe north to Svalbard, Asia, western N. America. The various chromosome races of A. undulatum form an autopolyploid series within which some cytological differentiation has taken place although the plants are morphologically indistinguishable. The plant known as ‘var. minus’ auct. non (Hedw.) Paris has a gametophyte similar to that of var. undulatum but rarely more than 2 cm high. The setae are c. 1 cm long, the capsules shortly cylindrical and often stunted or malformed, and the spores variable in size, 20–40 μm, with many aborted. It is usually present in small quantities often with var. undulatum and is generally distributed, being recorded from 48 vice-counties. It is in all probability a hybrid between different cytotypes or genotypes and cannot be recognised as a variety. Chromosome counts of n = 7, 14 and 21 have been reported for var. minus Fritsch, 1991, but whether these are from the same plant that occurs in Britain is unknown.

4 A. angustatum (Brid.) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1844 (Fig. 37) Catharinea angustata (Brid.) Brid. Dioicous. Dull green, sometimes red-tinged, lax tufts or patches, to 3 cm high. Leaves crisped when dry, stiff, patent, smooth to strongly undulate when moist,

8 Tetraphis

137

narrowly lingulate to lingulate-lanceolate, obtuse to acuminate, not narrowed towards insertion, lamina with scattered teeth on abaxial side above; margins dentate, sometimes spinosely so, from below middle; lamellae 3–4(–7), 5–9 cells high; costa ending in apex; cells ± hexagonal, 12–18(–20) μm wide in mid-leaf, smaller towards margins. Setae yellowish to purple; capsules narrowly cylindrical, erect and straight to inclined and curved; spores 12–14 μm. Capsules rare, winter. n = 7. On acidic soil in woods, especially on damp rides. Lowland. Locally frequent in Kent and Sussex, very rare elsewhere, Dorset, Surrey, N. Essex, E. Gloucester, Worcester, Carmarthen, W. Perth, Tyrone, Down. 10, H2. GB18 + 16∗ , IR2. European Temperate. Europe, Iceland, Caucasus, Turkey, Tenerife, Azores, N. America. Distinguished in the field from A. undulatum with which it sometimes grows by the narrower leaves and the sometimes slight reddish tinge. The plant referred to as var. rhystophyllum ¨ Hal.) P. W. Richards & E. C. Wallace has more strongly undulate and sharply toothed (Mull. leaves but intergrades with normal plants to such an extent that it is not worthy of taxonomic recognition. This species is considered endangered in the Red List of British mosses.

4 Tetraphidales Small acrocarpous plants. Leaves not differentiated into sheathing base and blade; costa narrow or absent, without adaxial lamellae. Peristome double, single or absent. Three families.

4 Tetraphidaceae Plants small. Leaves ovate or lanceolate; costa when present without lamellae on adaxial surface; cells rounded-hexagonal, smooth, unistratose. Capsules erect, symmetrical, smooth; annulus absent; peristome teeth 4, basal membrane lacking. Protonemata producing frondiform entire or forked outgrowths (protonemal leaves). Two genera. 8 TETRAPHIS HEDW., SP. MUSC. FROND., 1801 Autoicous. Stems with central strand. Stem leaves numerous, costa distinct. Capsules without stomata; calyptrae plicate. Protonemal leaves not persisting. Two north temperate species. Derivation: Referring to the four peristome teeth.

1 T. pellucida Hedw., Sp. Musc. Frond., 1801 (Fig. 38) Patches or tufts, bright green above, brownish below, to 15(–35) mm high. Leaves loosely appressed when dry, patent when moist, lower orbicular to ovate, upper ovate to lanceolate, acute; margins plane, entire; costa ending below apex; cells irregularly hexagonal, incrassate, 10–20 μm wide in mid-leaf. Uppermost leaves of sterile stems frequently crowded, orbicular, forming gemma-cups

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Fig. 38 1–5, Tetraphis pellucida: 1, leaves (×22.5); 2, shoot with gemma cup (×8); 3, mid-leaf cells (×450); 4, gemma (×80); 5, capsule (×22.5). 6–9, Tetrodontium brownianum: 6, plant (×20); 7, leaves (×22.5); 8, mid-leaf cells (×450); 9, protonemal leaves (×15). 10–12, T. repandum: 10, leaf (×22.5); 11, propaguliferous shoot (×60); 12, protonemal leaves (×30). 13–16, Oedipodium griffithianum: 13, leaf (×15); 14, marginal cells from middle of leaf (×300); 15, capsule (×15); 16, axillary gemma (×115).

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139

containing discoid gemmae c. 40 μm diameter. Perichaetial leaves narrowly lanceolate, acuminate. Setae straight, 4–15 mm long; capsules cylindrical; lid conical; peristome teeth 4; spores 10–12 μm. Capsules rare in lowland Britain, occasional elsewhere; throughout the year. n = 6, 7, 8∗ . On rotting wood, peat and sandstone rocks, calcifuge. 0–380 m. Frequent or common except in eastern England and N. Scotland, occasional in Ireland. 107, H33. GB1030 + 71∗ , IR61 + 5∗ . Circumpolar Boreo-temperate. Europe north to Fennoscandia, Caucasus, Turkey, Siberia, China, Japan, Korea, N. America. ¨ 9 TETRODONTIUM SCHWAGR., SP. MUSC. FROND. SUPPL. 2, 1824 Autoicous. Plants minute, bud-like; stems without central strand. Stem leaves few; costa weak or absent. Stomata present at base of capsule; calyptrae smooth. Protonemal leaves persistent. Three species. Derivation: referring to the four peristome teeth.

Protonemal leaves to 2.5 mm long, plants without flagelliform branches 1. T. brownianum Protonemal leaves to 0.5 mm long, flagelliform branches often present 2. T. repandum ¨ 1 T. brownianum (Dicks.) Schwagr., Sp. Musc. Frond. Suppl. 2, 1824 Tetraphis browniana (Dicks.) Grev.

(Fig. 38)

Plants gregarious, minute, to 2 mm high. Protonemal leaves to 2.5 mm long, linear to narrowly lingulate or narrowly spathulate, sometimes forked; margins entire; cells 2–3-stratose. Stem and perichaetial leaves imbricate, ovate to lanceolate, acuminate; costa lacking in lower leaves, weak in upper leaves; cells irregularly rectangular, very incrassate. Setae to 4 mm long; capsules ellipsoid; peristome teeth 4; spores 14–16 μm. Capsules common, summer. n = 8∗ . In crevices, on vertical surfaces and under overhangs of often slightly basic siliceous rock in shaded sites by streams and rivers. 0–700 m. Frequent in northern England and W. Scotland, rare or very rare elsewhere, Devon, Sussex, W. Gloucester, Stafford, Derby, Wales, rare in Ireland. 54, H9. GB161 + 20∗ , IR10 + 4∗ . Suboceanic Temperate. Pyrenees and Yugoslavia north to S. W. Norway, Caucasus, Turkey, Japan, N. America, Chile, New Zealand. ¨ 2 T. repandum (Funck) Schwagr., Sp. Musc. Frond. Suppl. 2, 1824 Tetraphis browniana var. repanda (Funck) Hampe

(Fig. 38)

Plants minute, gregarious. Protonemal leaves to 0.5 mm long, entire to coarsely and irregularly toothed; cells unistratose. Stem and perichaetial leaves imbricate, perichaetial leaves without costa or costa very poorly developed. Tristichous flagelliform shoots often present at base of stems. Capsules unknown in England.

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5 Oedipodiaceae

On the underside of moist gritstone or sandstone rock. Very rare, E. Sussex, N. E. Yorkshire. 2. GB2. Suboceanic Boreal-montane. From C. Europe north to Svalbard and Jan Mayen, Caucasus, China, Japan, western N. America, Newfoundland. For the occurrence of this plant in Britain see J. Appleyard, Trans. Br. Bryol. Soc. 3, 64–65, 1966. There is an unconfirmed nineteenth-century record from Cheshire. This species is regarded as critically endangered on the Red List of British mosses.

5 Oedipodiaceae A monotypic family with the characters of the only species. ¨ 10 OEDIPODIUM SCHWAGR., SP. MUSC. FROND. SUPPL. 2, 1823 Derivation: meaning swollen foot from the swollen hypophysis.

¨ 1 O. griffithianum (Dicks.) Schwagr., Sp. Musc. Frond. Suppl 2, 1823 (Fig. 38) Autoicous or synoicous. Acrocarpous. Lax pale green tufts or scattered plants, to 1 cm high. Leaves shrivelled when dry, soft, succulent, erect-patent to spreading when moist, obovate-spathulate to ± orbicular, with long narrow ciliate base, apices rounded; margins plane, entire; costa ending below apex; cells hexagonal, ± collenchymatous, smooth, 50–100 μm wide in mid-leaf. Discoid or oval stalked multicellular gemmae, to 300 μm long, often present in leaf axils. Setae succulent; capsules erect, shortly ellipsoid, brown, with long brownish hypophysis with numerous stomata, tapering into seta; peristome lacking; columella expanded above but not exserted after dehiscence; spores 24–30 μm. Capsules occasional, summer. On peaty soil in shaded rock crevices and boulder scree in montane areas. To 1200 m. Rare to occasional in Wales, the Lake District and the Scottish mountains, extending north to W. Ross, old records from S. Kerry and W. Donegal. 30, H2. GB48 + 30∗ , IR2∗ . Oceanic Boreal-montane. Norway, Sweden, Finland, Siberia, Japan, Canada, Alaska, Greenland, Falkland Is. Traditionally placed in the Funariales, DNA studies suggest that Oedipodium is most closely related to Tetraphis.

5 Buxbaumiales Dioicous. Acrocarpous. Protonemata persistent. Female plants with very short simple stems. Leaves very small, green in lower part, hyaline above with brown marginal cilia forming protective tomentum over base of seta; costa lacking. Perichaetial leaves similar to stem leaves, surrounding a single archegonium. Setae elongate, warty; capsules oblique, inclined, ovoid, asymmetrical, somewhat flattened on upper surface, tapering to small mouth; lid conical; outer peristome of 1–4 concentric rings of short teeth, inner conical, plicate. Male plants consisting

11 Buxbaumia

141

of a single leaf surrounding a single antheridium. One family and one genus with about 10 species.

6 Buxbaumiaceae 11 BUXBAUMIA HEDW., SP. MUSC. FROND., 1801 Derivation: named after a German botanist Johann Buxbaum (1693–1730).

Capsules glossy, cuticle not peeling from flattened upper surface 1. B. aphylla Capsules dull, upper surface scarcely flattened, cuticle splitting longitudinally and peeling from surface of capsule 2. B viridis 1 B. aphylla Hedw., Sp. Musc. Frond., 1801 (Fig. 39) Plants minute, solitary or scattered, usually but not always ephemeral, arising from brownish protonemal mat. Perichaetial leaves minute, ovate, ciliate, cilia

Fig. 39 1–6, Diphyscium foliosum: 1, leaves (×10); 2, leaf cells (×450); 3 and 4, outer and inner perichaetial leaves (×7.5); 5, capsule (×7.5); 6, shoot with sporophyte (×4). 7–8, Buxbaumia viridis: 7, sporophyte (×4); 8, part of seta (×25). 9–10, B. aphylla: 9, sporophyte (×4); 10, part of seta (×25).

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becoming filamentous with age and forming protonemal-like mass at base of setae. Male plants on side of female shoots. Setae erect, very coarsely papillose, (3–)5–10(–20) mm long; capsules glossy brown, with short neck, inclined to horizontal, ± obliquely ovoid, upper surface flattened with ± angular edges; exothecial cells sparsely and coarsely papillose; stomata immersed; cuticle peeling back from mouth but not from the upper side of ripe capsules; outer peristome teeth in a single row, filiform; spores (8–)10–13 μm. Capsules spring to autumn. n = 8. On humus-rich acidic sandy soil or occasionally on rotting wood, in shaded habitats, especially conifer woods, or on colliery spoil where colonies may persist for several years. Lowland. Very rare but widely distributed throughout Britain, S. Kerry (not seen recently). 33, H1. GB25 + 21∗ , IR1∗ . Circumpolar Boreal-montane. Europe, Caucasus, N. Asia, Japan, N. America, Australasia. The capsules of this pioneering species are disproportionately large relative to the size of the gametophyte and it is likely that in the later stages of development the sporophyte is nutritionally self-supporting. Despite the enormous spore output, c. 5 000 000 per capsule, the plant is usually only rarely encountered.

2 B. viridis (Moug. ex DC) Brid. ex Moug. & Nestl., Stirpes Cryptog. Vogeso-Rhenan, 1823 B. indusiata Brid.

(Fig. 39)

Gametophyte similar to that of B. aphylla. Setae coarsely papillose; capsules pale brown, not glossy, obliquely ellipsoid, scarcely angled or flattened on back; cuticle splitting longitudinally and peeling from upper side of capsule at maturity; stomata superficial; outer peristome of 4 concentric rows of teeth; spores c. 10 μm. Capsules summer. n = 8. Decaying wood in deciduous or more especially coniferous woodland. Lowland. Very rare and endangered; seen recently in E. Perth and E. Inverness with old records from Angus, S. Aberdeen and E. Ross. 5. GB2 + 3∗ . European Boreal-montane. Northern Europe, Corsica, Turkey, Caucasus, China, N. America. This species is considered endangered in the Red List of British Mosses and is a protected plant under the Wildlife and Countryside Act. It is also listed as vulnerable in the Red Data Book of European Bryophytes.

Class 4 Bryopsida

Acrocarpous or pleurocarpous. Plants minute to large; stems simple to much branched, with or without central strand. Leaves spirally arranged, rarely distichous; costa single or double, well developed or not, or lacking; cells usually unistratose except sometimes at margins or towards apex, isodiametric to linear, thin-walled to strongly incrassate, smooth, papillose or mamillose. Early divisions of zygote resulting in radially symmetrical embryo. Setae short or long; capsules erect to pendulous, globose to cylindrical, dehiscing by lid or more rarely cleistocarpous; mouth with peristome of one (haplolepideous mosses) or two (diplolepideous mosses) concentric rings of articulated teeth, each ring of 16 simple or variously divided teeth, teeth variously ornamented, sometimes reduced or absent; spore sac cylindrical, surrounding but not overtopping columella; spores usually small, to 40 μm, numerous, mostly 5000–50 000 000 per capsule, usually wind-dispersed. The nature of the peristome has been regarded as highly important in the classification of mosses. For accounts of the structure and ontogeny of peristome teeth see S. R. Edwards in Clarke & Duckett (1979) and S. R. Edwards in Schuster (1983).

Subclass 1 Diphysciideae Dioicous or autoicous. Acrocarpous. Protonemata persistent. Stems short, simple. Leaves lingulate or lingulate-spathulate; costa present; cells unistratose at base, 2(−3)-stratose above, rounded-quadrate, mamillose or smooth. Perichaetial leaves larger than stem leaves; margins ciliate above; costa longly excurrent. Setae very short; capsules oblique, ovoid, gibbous, terete, tapering to small mouth; lid conical; outer peristome of 16 very short teeth, inner conical with 16 plicae. One family, genera.

6 Diphysciales 7 Diphysciaceae 12 DIPHYSCIUM D. MOHR, OBSERV. BOT., 1803 About 29 mainly Northern Hemisphere genus. Derivation: referring to the double tissue of the exothecium and sporangium.

143

8 Archidiaceae

144

1 D. foliosum (Hedw.) D. Mohr, Observ. Bot., 1803 (Fig. 39) Dioicous. Green to brownish patches or scattered plants, shoots very short, to c. 5 mm high. Leaves crisped when dry, spreading, soft when moist, fragile, narrowly lingulate from a sometimes slightly sheathing base, obtuse to acute; margins plane, finely crenulate; costa poorly defined, ending below apex; cells incrassate, rounded-hexagonal, mamillose, 2–3-stratose, obscure, 10–12 μm wide, basal cells thinner-walled, smooth, basal marginal band hyaline, rectangular. Perichaetial leaves ± lanceolate, acute to obtuse; margins ciliate above; costa excurrent in long smooth or slightly denticulate setaceous point. Setae very short; capsules immersed or slightly exserted, oblique, ovoid, gibbous; peristome white, becoming brown with age; spores 8–13 μm. Capsules frequent, spring to autumn. n = 9∗ . On sheltered acidic peaty or mineral soil on banks, in rock crevices and by tracks and streams. 0–1205 m. Frequent in western and northern Britain, very rare elsewhere, Kent, E. Sussex, Oxford, Stafford, rare in most of Ireland. 67, H21. GB410 + 36∗ , IR36 + 6∗ . European Boreo-temperate. Europe north to Svalbard, Faeroes, Iceland, Caucasus, Turkey, Japan, Madeira, Azores, N. America, Mexico, Guatemala, Jamaica. When fertile readily recognised by the oblique ± immersed capsules, but sterile plants may be mistaken for Tortella species which, however, occur in base-rich usually exposed habitats and differ in leaf shape and unistratose cells.

Subclass 2 Dicranideae Plants acrocarpous or rarely cladocarpous. Peristome haplolepideous with exostome lacking, outer peristomial layer of 32 cells, primary peristomial layer of 16 cells and inner peristomial layer of 24 cells, late state division of the inner peristomial layer asymmetric.

7 Archidiales Acrocarpous. Plants small; stems with central strand. Stem leaves small, lanceolate. Perichaetial leaves larger with sheathing base. Early cell divisions of zygote resulting in a bilateral embryo. Setae lacking; capsules cleistocarpous, wall unistratose, columella and inner spore sac lacking; spores 4–176, thick-walled, 50–310 μm. One genus. It has been reported in the literature that the spores are derived from the outermost layer of the endothecium, but this is incorrect and they are derived from the amphithecium as in other mosses. For a monograph of Archidium see J. A. Snider, J. Hattori Bot. Lab. 39, 105–201, 1975.

8 Archidiaceae 13 ARCHIDIUM BRID., BRYOL. UNIV., 1826 About 30 species distributed ± throughout the world. Derivation: meaning primitive.

13 Archidium

145

1 A. alternifolium (Dicks. ex Hedw.) Mitt., Ann. Mag. Nat. Hist., 1851 (Fig. 40) Paroicous. Dense dull dark green, perennial tufts or patches, to 2 cm high. Plants consisting of simple or branched stems, often innovating from below perichaetium, or of long sterile and short fertile stems arising from old prostrate stems. Leaves distant on sterile stems, crowded on fertile stems, erect-patent when moist, lanceolate to lanceolate-subulate, acute to acuminate; margins plane, denticulate; costa ending ± in apex; cells incrassate, basal rectangular, cells above rhomboidal to narrowly hexagonal, 8–10 μm wide in mid-leaf. Perichaetial leaves much larger with broad sheathing base. Capsules immersed, cleistocarpous, globose, wall pellucid; spores angular, 127–262 μm. Capsules frequent, spring. n = 13, 26. On muddy to sandy open or disturbed soil in fields, old quarries, on moorland, woodland rides, by rivers and streams. 0–500 m. Very rare in eastern England, common in the west, occasional elsewhere, rare in Ireland. 99, H20, C. GB378 + 75∗ , IR31 + 6∗ , C2. European Southern-temperate. Europe north to southern Fennoscandia, Faeroes, Iceland, Turkey, Siberia, Macaronesia, N. Africa, N. America, Mexico. Large hyaline to pale brown moniliform gemmae, to 3(−4) mm long, have been reported from mainly southern European gatherings (T. Arts, Lindbergia 16, 59–61, 1990) but have not yet been detected in British plants.

8 Dicranales Acrocarpous. Plants very small to large. Apical cell of stem with 2 or 3 cutting faces. Leaves spirally arranged or distichous; cells quadrate to linear, usually smooth, sometimes porose, alar cells sometimes enlarged or otherwise differentiated. Setae usually long; capsules ovoid to cylindrical, frequently curved; peristome single, teeth usually bifid, with fine vertical striae between the transverse articulations, rarely capsules cleistocarpous. Thirteen families.

9 Ditrichaceae Plants usually small, stems with central strand. Upper leaves longer than lower usually straight, usually lanceolate, and acuminate or longly acuminate; costa percurrent or excurrent, narrow, in section with guide cells and two stereid bands; basal cells elongate, alar cells undifferentiated, cells above isodiametric to elongate, usually. Perichaetial leaves usually longer than stem leaves, often with sheathing bases. Setae very short or long, straight; capsules dehiscent or cleistocarpous, erect, usually cylindrical, straight or slightly curved, smooth or longitudinally striate, strumose or not, annulus usually of large cells, separating; peristome teeth 16, perforated or bifid nearly to base into terete segments, smooth below, smooth or papillose; calyptrae usually cucullate. Twenty-five genera. Differences between the Ditrichaceae and Dicranaceae are not clear cut although the differentiated alar cells of some genera of the latter are not found in the former. The Ditrichaceae differs from the Dicranaceae in the peristome teeth divided to the base into terete filiform papillose segments rather than flat teeth vertical pitted-striate below.

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Fig. 40 1–4, Archidium alternifolium: 1, plant (×15); 2, 3, stem and perichaetial leaves (×50); 4, leaf cells. 5–7, Pseudephemerum nitidum: 5, plant (×10); 6, perichaetial leaf (×20); 7, cells near leaf base. 8–10, Pleuridium acuminatum: 8, perichaetial leaf (×20); 9, leaf apex; 10, basal cells. 11–15, Pleuridium subulatum: 11, plant (×10); 12, 13, stem and perichaetial leaves (×20); 14, basal cells; 15, leaf apex. Cells ×450.

14 Pleuridium

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14 PLEURIDIUM RABENH., DEUTSCHL. KRYPT. FLORA., 1848 Small plants with usually unbranched stems. Perichaetial leaves much larger than stem leaves, with sheathing base tapering to acuminate apex. Setae very short; capsules immersed, erect, cleistocarpous, stomata only at base; calyptrae cucullate. A mainly Northern Hemisphere genus of about 30 species, a few of which occur in S. America and Australia. Derivation: meaning on one side, apparently referring to capsules being lateral.

Plants paroicous, antheridia in persistent dwarf axillary buds, cells at shoulder of perichaetial leaves unistratose 1. P. subulatum Plants paroicous, antheridia naked in outer perichaetial leaf axils, cells at shoulder of perichaetial leaves bistratose 2. P. acuminatum 1 P. subulatum (Hedw.) Rabenh., Deutschl. Krypt. Flora., 1848 P. alternifolium Dixon

(Fig. 40)

Autoicous. Green to yellowish green tufts or patches, to c. 1 cm high. Stem leaves from ovate basal part tapering to acuminate apex, upper longer, merging into perichaetial leaves; upper and perichaetial leaves from ovate basal part usually abruptly narrowed to long denticulate setaceous acumen; basal cells rectangular, cells at shoulder of perichaetial leaves unistratose, upper cells rectangular to narrowly rectangular, c. 8 μm wide. Antheridia in persistent dwarf axillary branches. Capsules common, spring, summer. n = 13. In similar to or sometimes less acidic habitats than P. acuminatum. 0–380 m. Occasional in England (except the east), Wales and S. E. Scotland, rare elsewhere, extending north to Orkney, very rare in Ireland. 90, H10, C. GB246 + 87∗ , IR4 + 9∗ , C2. Circumpolar Temperate. Europe, Iceland, Turkey, Caucasus, Palestine, Macaronesia, N. Africa, N. America, New Zealand, Oceania. ¨ 2 P. acuminatum Lindb., Ofvers F¨orh. Kongl. Svenska Vetensk Akad., 1863 (Figs. 40, 41) P. subulatum F. Weber & D. Mohr Paroicous. Green or yellowish green tufts or patches, to c. 1 cm high. Lower leaves spreading, lanceolate or ovate, acuminate, upper longer, ± erect or slightly secund, merging into perichaetial leaves; upper and perichaetial leaves from ovate-lanceolate basal part usually gradually tapering to long acuminate apex; margins entire or slightly denticulate; costa broad, obscure below, excurrent in upper leaves; basal cells rectangular, cells at shoulder of perichaetial leaves irregularly bistratose, cells above becoming ± linear, c. 8 μm wide. Pale to dark brown, spherical to elongate rhizoidal gemmae with slightly bulging cells, with a hyaline outer layer, to 120 μm diameter or 400 μm long, sometimes present. Antheridia naked in axils of perichaetial leaves. Capsules immersed and ± concealed by perichaetial leaves, cleistocarpous, ovoid with blunt apiculus; spores 22–30 μm.

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Capsules common, spring, summer. n = 13∗ , 26. In slightly shaded or exposed habitats on soil in fields, waste places, heaths, moorland, open places in woodland, calcifuge. 0–450 m. Common and sometimes locally abundant in England (except in the east), Wales and S. E. Scotland, rare elsewhere and in Ireland. 105, H21, C. GB659 + 104∗ , IR20 + 13∗ , C6. European Temperate. Europe, Caucasus, Turkey, Cyprus, Macaronesia, Algeria, China, N. America. Plants of P. acuminatum with capsules are usually devoid of antheridia but the dwarf antheridial branches of P. subulatum persist. Also, rhizoidal gemmae have only been found in P. acuminatum. It has been shown that the shape of the perichaetial leaves is an unreliable character for separating the two species but that the cells at the shoulder of the perichaetial leaves of P. subulatum are unistratose whilst those of P. acuminatum are irregularly bistratose (see K. L. Yip., Bryologist 105, 259–61, 2002). Some authorities treat P. acuminatum and P. subulatum as synonymous, as in some mixed populations intermediates occur. However, it is possible that these intermediates are of ` de Lecq and Les hybrid origin. A curious form of P. acuminatum occurs on Jersey (at Greve Landes, St. Ouen’s) in which the perichaetial leaves are about 1/2 –2/3 the length of those in typical plants. The taxonomic status of this form is uncertain as it is not known whether intermediates between it and typical plants occur.

15 PSEUDEPHEMERUM (LINDB.) I. HAGEN, NORSK VID. SELSK. SKRIFT., 1910 A monotypic genus with the characters of the species (see T. Matzui & Z. Iwarsuki, J. Hattori Bot. Lab. 68, 317–66). Derivation: referring to the resemblance to the genus Ephemerum. Placed in the Dicranaceae by many authorities but the genus seems close to Pleuridium on the basis of chromosomal similarity and this is supported by the reported occurrence of hybrids between species of the two genera. Further, DNA studies (M. Stech, Inaugural ¨ ¨ dissertation zur Erlangung der Doctorwurde Freien UniversitatBerlin) indicate a close relationship to Trichodon cylindricus.

1 P. nitidum (Hedw.) Loeske, Stud. Morph. Syst. Laubm., 1910 Pleuridium axillare (Sm.) Lindb.

(Fig. 40)

Synoicous. Patches or scattered very small plants, to 5 mm high, pale green, becoming orange-brown with age. Stems with central strand. Leaves increasing in size up stems, upper and perichaetial leaves of similar length, patent when moist, lanceolate, longly acuminate; margins entire below, denticulate above; costa ending below apex, in section with stereid band; cells lax, thin-walled, rectangular to narrowly rectangular throughout, 10–15 μm wide. Setae very short; capsules immersed but conspicuous, cleistocarpous, ovoid with conical beak, thin-walled, orange-brown when ripe; spores 20–32 μm. Capsules common throughout the year but especially late summer and autumn. In deep shade to exposed sites on damp soil on banks, cultivated ground, woodland rides. Lowland. Frequent or

17 Ditrichum

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common in most of England and Wales, rare or occasional elsewhere, occasional in Ireland. 105, H26, C. GB640 + 76∗ , IR68 + 3, C4. European Temperate. Europe, Sri Lanka, Assam, Nepal, Japan, Macaronesia, Algeria, Morocco, Congo Kenya, Rwanda, Zaire, Madagascar, British Columbia, Oregon, Mexico, Brazil, Tasmania, New Zealand. Distinguished from Pleuridium species by the upper leaves being of similar length to the perichaetial leaves and, because of the shorter perichaetial leaves, the more conspicuous capsules. Gemmae are produced by P. nitidum, but only rarely. When present they are numerous, bright yellow to pale orange-brown, mulberry-shaped, 60–160 × 45–110 μm (see T. Arts & S. Risse, Lindbergia 17, 55–8, 1992).

16 TRICHODON SCHIMP., COROLL. BRYOL. EUR., 1855 A monotypic genus with the characters of the species. Derivation: meaning hair-like tooth, referring to the divisions of the peristome teeth. For the reasons for recognising this genus see R. S. Seppelt, Bryobrotheria 5, 1189–94, 1999.

1 T. cylindricus (Hedw.) Schimp., Coroll. Bryol. Eur., 1855 Ditrichum cylindricum (Hedw.) Grout, D. tenuifolium Lindb.

(Fig. 41)

Dioicous. Dull, yellowish green tufts, patches or scattered plants, to 5 mm high. Stems usually simple. Upper leaves squarrose-flexuose, from oblong sheathing basal part abruptly narrowed to long acumen composed almost entirely of costa, denticulate all round and not just at margins; margins plane; cells in sheathing base rhomboidal, 2–3 marginal rows narrowly rectangular, upper cells rectangular. Brownish, ovoid, 1–3-celled rhizoidal gemmae, c. 130 μm long, usually present. Setae reddish below, yellow above; capsules erect, cylindrical, straight or slightly curved; lid longly rostrate; spores 12–16 μm. Capsules very rare, summer. n = 12, 13. On disturbed soil in fields, on roadsides, banks, open places in woodland. 0–700 m. Common in lowland areas, rare elsewhere. 111, H23, C. GB748 + 51∗ , IR56 + 3∗ , C2. Circumpolar Boreo-temperate. Europe north to Svalbard, Faeroes, Iceland, N. Asia, Japan, Tenerife, N. America. The squarrose longly acuminate leaves will readily distinguish T. cylindricus from most other arable mosses except Dicranella schreberiana (q.v.). Pleuridium species are autoicous or paroicous and the capsules are very common and immersed; Dicranella staphylina has much shorter non-squarrose leaves and gemmae 3–4 cells long and 1–3 cells wide.

17 DITRICHUM HAMPE, FLORA, 1876 Usually dioicous. Leaves from lanceolate basal part gradually tapering to long or short frequently channelled acumen; costa often broad, ending below apex to excurrent; cells in lower part of leaf linear to ± rectangular, in upper part quadrate or rectangular, smooth. Setae long; capsules ± erect, narrowly ellipsoid or

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Fig. 41 1–3, Trichodon cylindricus: 1, leaves (×20); 2, basal cells; 3, leaf apex. 4–7, Ditrichum zonatum var. zonatum: 4, leaves (×50); 5, basal cells; 6, mid-leaf cells; 7, leaf apex. 8, D. zonatum var. scabrifolium: leaf apex (×220). 9–12, Rhizoidal gemmae (×220): 9. Trichodon cylindricus; 10, Ditrichum heteromallum; 11, D. subulatum; 12, Pleuridium acuminatum. Cells ×450.

17 Ditrichum

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cylindrical, straight or slightly curved, smooth; peristome teeth 16, divided to base into papillose filiform segments. A cosmopolitan genus of c. 90 species. Derivation: meaning two hairs, referring to the divided peristome teeth. The sporophytes of some species of Ditrichum and Dicranella are very similar. Ditrichum differs from Dicranella in the peristome teeth divided to the base into filiform papillose not vertical pitted-striate below. In Dicranella the teeth are divided to about the middle into flat segments and are papillose above and pitted-striate below. For an account of rhizoidal and protonemal gemmae in European Ditrichum species see T. Arts, J. Bryol. 18, 43–61, 1994.

1 Plants 1–11 cm high, leaves ± abruptly narrowed from broad basal part to long acumen composed largely of costa 2 Leaves gradually tapering to long or short apex or if abruptly narrowed above basal part then plants not more than 1 cm high 3 2 Leaves mostly 1.0–3.5 mm long, basal part constituting 1/3 –1/2 total leaf length, marginal cells at middle of basal part thick-walled, not hyaline 8. D. flexicaule 1 1 Leaves mostly 3–8 mm long, basal part constituting /4 – /3 total leaf length, marginal cells at middle of basal part thin-walled and hyaline 9. D. gracile 3 Paroicous, leaves abruptly narrowed above basal part into long acumen 7 D. subulatum Dioicous, leaves ± gradually tapering from widest part to long or short apex 4 4 Leaves tapering to long acumen consisting largely or entirely of costa 5 Leaves shortly pointed, costa not constituting all or much of upper part of leaf 7 5 Leaf margins recurved at least at middle part of leaf, denticulate above 1. D. pusillum Leaf margins plane or narrowly recurved, entire or with a few denticulations near apex only 6 6 Cells in lower part of leaf narrowly rectangular to linear, mostly 40–80 μm long, sporophytes common 5. D. heteromallum Cells in lower part of leaf rectangular, mostly 10–24 μm long, sporophytes unknown 6. D. zonatum 7 Leaves erect-patent to patent when moist, cells in lower part of leaf 7–12 × 15–25 μm 2. D. cornubicum Leaves appressed when moist, cells in widest part of leaf 5–9 × 15–46 μm 8 8 Upper leaves 3–4 times as long as wide, margins recurved on one or both sides 3. D. lineare Upper leaves 2–3 times as long as wide, margins plane 4. D. plumbicola 1 D. pusillum (Hedw.) Hampe, Flora, 1867 D. tortile (Schrad.) Brockm.

(Fig. 42)

Dioicous. Dull green tufts, to 10 mm high; stems usually simple. Leaves erectpatent, slightly secund, lower ovate-lanceolate, acute, upper larger, lanceolate,

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Fig. 42 1–4, Ditrichum subulatum: 1, leaf; 2, leaf apex; 3, basal cells; 4, capsule. 5–9, D. heteromallum: 5, leaf; 6, basal cells; 7, marginal cells at middle of leaf; 8, leaf apex; 9, capsule. 10–13, D. pusillum: 10, leaves; 11, basal cells; 12, capsule; 13, rhizoidal gemmae (×175). Leaves ×30, cells ×450, capsules ×20.

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narrowing to channelled acumen; margins denticulate, recurved at least at middle of leaf; costa stout, percurrent or excurrent; cells in lower part of leaf narrowly rectangular, 10–12 μm wide, narrower and shorter towards margins, cells above quadrate to rectangular. Yellow or yellowish brown, pyriform rhizoidal gemmae, 100–150 × 75–100 μm, abundant on sterile plants, occasional on fertile plants. Setae red; capsules erect, ovoid to cylindrical; spores 12–15 μm. Capsules frequent, winter. n = 13∗ . On sandy soil and in quarries, rarely but probably overlooked in non-calcareous arable fields. 0–900 m. Rare, widely distributed from S. England to N. W. Scotland, very rare in Ireland and not seen recently. 24, H6. GB24 + 10∗ , IR4∗ . Circumpolar Boreo-temperate. Europe, Iceland, Caucasus, Siberia, Amur, India, Madeira, Tenerife, Algeria, N. America. Plants in arable fields lack capsules and may be very depauperate, resembling juvenile Ceratodon purpureus but are readily recognised by the rhizoidal gemmae (see H. L. K. Whitehouse, J. Bryol. 9, 7–11, 1976).

2 D. cornubicum Paton, J. Bryol., 1976. (Fig. 43) Dioicous. Dull green patches or scattered plants, Very small, 1–5 mm high. Lower leaves distant, upper more crowded, appressed, uppermost on well grown stems slightly secund when dry, erect-patent to patent when moist, 0.4–0.9 mm long, c. 3 times as long as wide, widest c. 1/4 from base, concave, lanceolate, tapering to obtuse to sub-acute apex; margins plane with a few obscure denticulations above; costa broad, ending just below apex; cells in lower part of leaf irregularly rectangular, 1–2 marginal rows narrower, cells above rectangular, narrowly rectangular by costa, 7–10(−12) × 15–25 μm at widest part of leaf. Brownish multicellular rhizoidal gemmae, spherical to ovoid or irregular in shape, 80–160 μm long, present. Only male plants known. On peaty soil on copper-mine waste. A very rare and endangered species known from only two localities in Cornwall. 2. GB2. Endemic (Oceanic Temperate). For a description of this plant see J. A. Paton, J. Bryol. 9, 171–5, 1976. D. plumbicola is considered endangered in the Red List of British Mosses and is a protected plant under the Wildlife and Countryside Act. It is listed as critically endangered on the European Red List.

3 D. lineare (Sw.) Lindb., Acta Soc. Sci. Fenn., 1871 D. vaginans (Sull.) Hampe

(Fig. 43)

Dioicous. Dense green or yellowish green tufts, patches or scattered plans, 5–15 mm high. Shoots slender, stems innovating from below. Leaves rigid, loosely appressed, scarcely altered when dry, lower leaves small, ovate to ovate-lanceolate, shortly pointed, upper larger, 0.6–1.4 mm long, 3–4 times as long as wide, widest c. 1/4 from base, lanceolate, channelled above, tapering to bluntly pointed to acuminate apex; margins frequently narrowly recurved on one or both sides, entire or obscurely denticulate towards apex; costa broad, percurrent to shortly

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Fig. 43 1–6, Ditrichum lineare: 1, leaf (×45); 2, basal cells; 3, mid-leaf cells; 4, leaf apex; 5, section at middle of leaf; 6, stem section. 7–13, D. plumbicola: 7, leaves (×45); 8, basal cells; 9, mid-leaf cells; 10, leaf apex; 11, section at middle of leaf; 12, stem section; 13, rhizoidal gemma (×220). 14–20, D. cornubicum: 14, leaves (×65); 15, basal cells; 16, mid-leaf cells; 17, leaf apex; 18, section at middle of leaf; 19, stem section; 20, rhizoidal gemma (×160). Sections and apices ×300, cells ×420.

17 Ditrichum

155

excurrent; cells thick-walled, in lower part of leaf narrowly rectangular, sometimes becoming narrower towards margins, cells above rectangular to narrowly rectangular, 5–8 × 15–46 μm at widest part of leaf. Setae yellowish; capsules ellipsoid; spores c. 12 μm. Only female plants known in the British Isles. n = 13, 13 + m. On disturbed acidic soil on montane ridges and in areas of late snow-lie, on banks in woodland, by streams and lanes. 100–1040 m. Rare, Mid and N. Wales, Westmorland, Kirkcudbright, Scottish Highlands, Lewis, Sligo and Antrim but not seen recently. 18, H2. GB39 + 1∗ , IR2∗ . European Boreal-montane. C. and N. Europe, Spain, Iceland, Japan, eastern N. America. Rhizoidal gemmae similar to those of Ditrichum heteromallum have been reported from Belgian and Japanese plants but have not been detected in British or Irish plants. D. cornubicum, D. lineare and D. plumbicola are somewhat similar in appearance and easily confused. D. plumbicola has more shortly pointed leaves with plane margins, the stem is less triangular in section and the costa is thinner and less prominent at the back; the plant occurs on lead-containing soils, a habitat from which D. lineare is not known. The leaves of D. cornubicum are intermediate in shape between those of the other two species but they differ in being erect-patent to patent when moist and with shorter wider cells in the widest part of the leaf. D. lineare and D. plumbicola are superficially similar in appearance to Aongstroemia longipes but differ in leaf shape and areolation.

4 D. plumbicola Crundw., J. Bryol., 1976 (Fig. 43) Dense pale yellowish green ± glossy patches. Shoots very slender, 5–15 mm high. Leaves closely appressed, scarcely altered when dry, of ± similar size except at base of stems, 0.4–0.7 mm long, 2–3 times as long as wide, widest 1/3 –1/2 from base, concave, ovate to ovate-lanceolate, channelled above, shortly tapering to blunt apex; margins plane or in young leaves incurved above, entire or with a few obscure denticulations towards apex; costa broad, percurrent; cells thick-walled, in lower part of leaf narrowly rectangular, narrower or not towards margins, cells above rectangular to quadrate, 5–9 × 15–42 μm at widest part of leaf. Dark reddish brown rhizoidal gemmae consisting of 5–8 cells spirally twisted into a subspherical helix, 150–200 μm diameter, sometimes sparsely present. Gametangia and sporophytes unknown. On lead-mine spoil. 0–460 m. Very rare, W. Cornwall, N. Somerset, Mid and N. Wales, 9. Northumberland, I. of Man, Mid Perth. 8. GB12. Oceanic Temperate. Germany. For an account of this plant see A. C. Crundwell, J. Bryol. 9, 167–9, 1976. This plant is listed as vulnerable in the Red Data Book of European Bryophytes.

5 D. heteromallum (Hedw.) E. Britton, N. Am. Fl., 1913 D. homomallum (Hedw.) Hampe

(Figs. 41, 42)

Dioicous. Slightly silky yellowish green lax tufts or patches, seldom more than 1 cm high. Leaves erect-patent to subsecund, from ovate to lanceolate basal part tapering to channelled acumen; margins plane, entire; costa ill-defined below,

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occupying most of upper part of leaf and excurrent in slightly denticulate point; cells in lower part of leaf narrowly rectangular to linear, 6–10 × (24−)40–80 μm, cells above linear by costa, rectangular at margins. Dark reddish brown rhizoidal gemmae consisting of a uniseriate row of 3–9 thick-walled cells spirally twisted into a subspherical helix c. 90–300 μm diameter, occasionally and sometimes sparsely present. Setae purple; capsules erect, narrowly ellipsoid, ± straight; spores 12–18 μm. Capsules common, spring. n = 13∗ , 13 + m. On soil on banks by streams, paths, in woods and on moorland, calcifuge. 0–820 m. Very rare in lowland England except the extreme south, common elsewhere, frequent in W. Ireland and occasional in other parts. 95, H29. GB587 + 83∗ , IR90 + 4∗ . European Boreo-temperate. Europe north to Svalbard, Faeroes, Iceland, N., W. and E. Asia, N. Africa, western N. America, Tierra del Fuego. Small forms of Dicranella heteromalla without sporophytes may be confused with this plant but differ in the relatively wider costa, which is c. 1/3 width of leaf base and is also biconvex in section, whereas in Ditrichum heteromallum it is flat on the adaxial side.

6 D. zonatum (Brid.) Kindb., Bot. Not., 1882 D. homomallum var. zonatum (Brid.) Lindb. Dioicous. Small dark tufts or large dense cushions, glossy green above, reddish below. Shoots 0.3–5.0 cm high, often with annual growth zones when forming dense tufts; stems fragile. Leaves erect to erect-patent, tapering from ovate or ovate-lanceolate basal part to short channelled acumen; margins plane below, erect or sometimes slightly incurved above, entire; costa stout, extending to apex or percurrent; cells in lower part of leaf rectangular to narrowly rectangular, (5−)6–8 × 10–24(−32) μm, shorter towards margins and costa, in upper part of leaf shortly rectangular or quadrate, bistratose. A few dark reddish brown rhizoidal gemmae, similar to those of D. heteromallum, very occasionally present. Capsules unknown in the British Isles. European Arctic-montane. Cells and abaxial side of costa in upper part of leaves smooth Cells and abaxial side of costa in upper part of leaves papillose

var. zonatum var. scabrifolium

Var. zonatum (Fig. 41) Cells and abaxial side of costa in upper part of leaf smooth. Small cushions on rocks and dense tufts in rock crevices, in areas of late snow-lie and in scree, calcifuge. (400−)800–1335 m. Rare, Mid and N. Wales, N. England, Scottish Highlands, Antrim (not seen recently). 26, H1. GB76 + 6∗ , IR2 + 1∗ . Pyrenees and Alps north to Fennoscandia, Alaska. Var. scabrifolium Dixon, J. Bot. Lond., 1902 (Fig. 41) Cells and abaxial side of costa in upper part of leaf scabrous with large conical papillae. Damp rock crevices, especially where slightly basic. Usually at high altitudes.

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157

Rare, mid and N. Wales, Westmorland, Kirkcudbright, Scottish Highlands, W. Galway, W. Donegal. 19, H2. Canada. Well grown plants are easily recognised by the dense tufts, green above and reddish-brown below but the plant also occurs, looking very different, as small cushions on exposed rocks. These, and also large plants, may be recognised by the brittle stems, which make removal of the leaves difficult, and the ± quadrate mid-leaf cells. D. zonatum is distinct from D. heteromallum in habit and lamina cells extending ± to the leaf apex. In its typical form var. scabrifolium is very distinctive, although the papillae may be lost in old specimens; as there are some ecological differences between the type and var. zonatum the variety seems to be a sound taxon.

7 D. subulatum Hampe, Flora, 1867 (Figs. 41, 42) Paroicous. Silky yellowish green tufts or patches to 8 mm high. Leaves distant below, crowded above, lower small, narrowly lanceolate, upper larger, from ovate or oblong base abruptly narrowed into long channelled acumen composed largely of costa, uppermost and perichaetial leaves falcate-secund; margins plane below, erect or inflexed and entire or slightly denticulate above; costa longly excurrent in upper leaves; basal cells in lower leaves quadrate to quadrate-rectangular, in upper leaves variable in shape, rectangular or rhomboidal to narrowly rectangular, 8–14 μm wide, narrower towards margins and apex. Dark reddish brown rhizoidal gemmae, similar to those of D. heteromallum, often present. Setae yellowish red; capsules erect, ovate-ellipsoid; spores 14–18 μm. Capsules common, winter, spring. n = 14∗ . On shaley soil in rock crevices and on rocky or earthy roadside banks. Lowland. Very rare, seen recently only in Cornwall, old records from S. Devon, E. Kent. 4. GB8 + 3∗ . Mediterranean-Atlantic. Mediterranean region, W. France, Macaronesia, N. America. ¨ 8 D. flexicaule (Schwagr.) Hampe, Flora, 1867 D. flexicaule auct. var. densum (Bruch & Schimp.) Braithw.

(Fig. 44)

Dioicous. Bright to dark green, dense or very dense, rarely lax tufts or patches, 1–5(−6) cm high. Stems fragile, densely tomentose below. Leaves erect, rarely flexuose or secund when moist, apices not twisted together when dry, 1.0–3.5 mm long, from sheathing basal part, constituting 1/3 –1/2 total leaf length, abruptly tapering to entire channelled acumen; costa broad, indistinct below, longly excurrent; cells in basal part variable in shape, near costa shortly rectangular to rectangular, cells above ± uniformly quadrate to shortly rectangular, incrassate, marginal cells about half way up basal part thick-walled, ± quadrate to oval, rarely rectangular, not hyaline, cells in acumen rectangular. Deciduous flagelliform shoots often present. Perichaetial leaves from sheathing base narrowed to long acumen. Capsules not known in the British Isles. On basic soil, in grassland, sand-dunes, quarries, on walls and cliff ledges. 0–1200 m. Widely distributed but apparently rare, from Cornwall east to E. Sussex and north to Sutherland, a few localities in

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Ireland. 37, H5, C. GB7 + 42∗ , IR5. Circumpolar Wide-temperate. Spain, Austria and Romania north to Svalbard, Caucasus, Siberia, northern N. America, Greenland. This is the plant referred to by Dixon & Jameson (1924) as D. flexicaule var. densum Bruch & Schimp. There are numerous collections of this plant made during the nineteenth and the first few years of the twentieth century, especially from Derbyshire, but it has been ignored since. It is probably considerably more common than the number of records suggests and the large number of old gatherings is a reflection of the lack of interest in the plant over the last 100 years or so. For a detailed comparison of D. flexicaule and D. gracile see A. A. Frisvoll, Bryologist 88, 31–40, 1985 and A. J. E. Smith, Bull. Br. Bryol. Soc. 61, 45–54, 1993. For differences from D. gracile see under that species.

9 D. gracile (Mitt.) Kuntze, Rev. G´en. Pl., 1891 (Fig. 44) ¨ Hal.) Paris, D. flexicaule auct. non (Schwagr.) ¨ D. crispatissimum (Mull. Hampe Dioicous. Yellowish green to green, often glossy and silky, lax to moderately dense tufts or patches, (2−)4–11 cm high. Stems fragile, usually only sparsely tomentose below. Leaves erect to secund when moist, flexuose, with apices sometimes twisted together when dry, 3–6 mm long, from sheathing basal part constituting 1/ –1/ total leaf length gradually tapering to long channelled entire to finely den4 3 ticulate acumen; costa broad, indistinct below, longly excurrent; sheathing part with basal cells near costa rectangular to very narrowly rectangular, cells above uniformly rectangular to elongate or more usually variable in size with mixed rounded to elongate often curved cells, rarely cells ± quadrate, marginal cells about half way up basal part very thin-walled, hyaline, narrowly rectangular to linear, rarely shorter, cells in acumen rectangular. Flagelliform shoots lacking. Innermost perichaetial leaves with sheathing base abruptly narrowed into acumen. Capsules ellipsoid, slightly curved; very rare, found at two localities in Scotland and not seen since 1902. n = 13. On soil in grassland, sand-dunes, quarries and on cliff ledges, calcicole. 0–1180 m. Common in basic areas, rare elsewhere. 91, H29, C. GB561 + 88∗ , IR88 + 9∗ , C2 + 2∗ . Circumpolar Boreo-temperate. Europe, Faeroes, Iceland, Siberia, China, New Guinea, N. America, Greenland, Guatemala, New Zealand. This is the plant referred to in both old and recent floras as D. flexicaule. D. flexicaule s.s. and D. gracile are very close and occasional plants are encountered that are difficult to determine. However, D. gracile usually differs in its larger size, hardly tomentose stems, lack of flagelliform shoots, the leaves flexuose when dry, the relatively shorter sheathing basal part more gradually tapering into the acumen and the areolation of the sheathing base.

18 SAELANIA LINDB., UTKAST EUR. BLADMOSS, 1878 A monotypic genus with the characters of the species. Derivation: named after a Finnish botanist Anders T. Saelan (1834–1921)

18 Saelania

159

Fig. 44 1–3, Ditrichum flexicaule: 1, leaves; 2, and 3, marginal and inner cells from middle part of leaf base; a and b, each from different gatherings. 4–7, D. gracile: 4, leaves; 5, perichaetial leaf; 6 and 7, marginal and inner cells from middle part of leaf base; c and d each from different gatherings. Leaves ×15, cells ×420.

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1 S. glaucescens (Hedw.) Broth. in Bomansson & Broth., Herb. Musc. Fenn. (ed. 2) Musci, 1894 (Fig. 46) S. caesia (Villars ex P. Beauv.) Lindb. Autoicous. Glaucous, bluish green tufts, to 3.5 cm high. Leaves appressed, upper flexuose when dry, erect-patent when moist, lower tapering ± from base to apex, upper longer, gradually tapering from narrowly lanceolate basal part to narrow acuminate apex; margins plane, bluntly toothed above; costa ending in or below apex in lower leaves, percurrent or excurrent in upper; basal cells in lower leaves rectangular, becoming ± quadrate above, in upper leaves basal cells rectangular or narrowly rectangular, becoming rectangular to quadrate-rectangular in mid-leaf, longer above, c. 10 μm wide in mid-leaf. Setae to 1 cm long; capsules erect, narrowly ellipsoid; smooth when moist, rugose when dry and empty; peristome teeth divided into papillose filiform segments; spores 14–16 μm. Capsules occasional, late summer. n = 13, 13 + m. On usually damp shaded soil over basic montane rock. C. 600 m. Very rare but locally frequent, Angus and E. Inverness. 2. GB2. Circumpolar Boreo-arctic Montane. Pyrenees, Alps and Carpathians north to Svalbard, Iceland, Turkey, Caucasus, N. Asia, Himalayas, N. America, Greenland, southern Africa, New Zealand, Hawaii. The glaucous appearance of this species is due to a covering of fungal hyphae. This species is treated as vulnerable in the Red List of British Mosses and is protected under the Wildlife and Countryside Act. It is also listed as vulnerable in the Red Data Book of European Bryophytes.

19 DISTICHIUM BRUCH & SCHIMP. IN BRUCH ET AL., BRYOL. EUR., 1846 Leaves distichous, acuminate from broad whitish sheathing basal part; cells of acumen quadrate to rectangular, papillose. Capsules ovoid to cylindrical; peristome teeth strongly perforated or irregularly divided. A cosmopolitan genus of c. 8 species. Derivation: referring to the leaves arranged in two ranks.

Plants glossy, bright green above, reddish brown below or dull green, capsules erect or slightly inclined, spores 17–22 μm, paroicous 1. D. capillaceum Plants dull green, capsules inclined, spores 30–40 μm, autoicous 2. D. inclinatum 1 D. capillaceum (Hedw.) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1846 (Fig. 45) Swartzia montana Lindb. Paroicous. Silky loose or compact tufts, bright green above reddish brown below, or more rarely dull green, to 10(−15) cm high. Stems radiculose. Leaves strongly

19 Distichium

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Fig. 45 1–3, Distichium capillaceum: 1, plant; 2, leaf; 3, cells at shoulder of sheathing base. 4–6, D. inclinatum: 4, plant; 5, leaf; 6, cells at shoulder of sheathing base. 7–9, Trematodon ambiguus: 7, leaf; 8, cells near shoulder of leaf base; 9, capsule (×15). Shoots ×5, leaves ×15, cells ×450.

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distichous, erect to spreading, flexuose when dry, reflexed, often sharply so when moist, basal part sheathing, whitish, abruptly narrowed into sharply reflexed setaceous denticulate acumen composed mainly of excurrent costa; basal cells of sheathing part narrowly rectangular, cells above rectangular, cells in acumen shortly rectangular. Antheridia naked in axils of upper leaves. Setae to 15 mm long; capsules ovoid to cylindrical, erect or slightly inclined; peristome teeth c. 40 μm wide at base, irregularly split into filiform segments; spores 17–22 μm. Capsules frequent, summer. n = 14∗ , 28. On soil, boulders and on rock ledges, in damp basic sites or where there is basic seepage, in montane habitats, also occasionally in basic lowland grassland by streams and rivers and in dune-slacks. 0–1205 m. W. Cornwall, frequent or common in the mountains in S. and N Wales, N. England and the Scottish Highlands and in N. W. Ireland, very rare elsewhere in Ireland. 49, H13. GB230 + 30∗ , IR20 + 9∗ . Circumpolar Boreo-arctic Montane. More or less cosmopolitan. When well grown the dense bright green silky tufts, reddish brown below, and sharply reflexed leaves readily distinguish this plant from D. inclinatum, but small dull green plants with less sharply reflexed leaves which may occur on sand-dunes or in other lowland habitats cannot be distinguished from D. inclinatum in the absence of capsules; such plants from N. Somerset and Surrey have been named D. capillaceum but their identity is uncertain.

2 D. inclinatum (Hedw.) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1846 (Fig. 45) Swartzia inclinata (Hedw.) P. Beauv. Autoicous. Dull or dark green tufts or patches. Plants to 5 cm high. Leaves distichous, flexuose when dry, somewhat reflexed when moist, abruptly narrowed from sheathing basal part into ± reflexed denticulate acumen composed mainly of excurrent costa; basal cells of sheathing part narrowly rectangular, cells above rectangular, cells of acumen shortly rectangular. Antheridia in dwarf axillary branches. Setae to 10 mm long. Capsules ovoid, inclined; peristome teeth 40– 50 μm wide at base, irregularly perforated but not split; spores 30–40 μm. Capsules frequent, summer. n = 13, 14. In calcareous sand-dunes and grassland, in quarries and on rock ledges. 0–950 m. Occasional but sometimes locally abundant, scattered localities from W. Cornwall, N. Somerset and S. Wales north to Shetland, rare in N. W. Ireland. 39, H10. GB62 + 13∗ , IR9 + 3∗ . Circumpolar Boreo-arctic Montane. Europe north to Svalbard, Turkey, N. and C. Asia, Japan, N. America. This and small forms of D. capillaceum may be confused with Ditrichum gracile or D. flexicaule but differ in the distichous leaves with acumen reflexed and more abruptly narrowed from the base.

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20 CERATODON BRID., BRYOL. UNIV., 1826 Dioicous. Leaves ovate to narrowly lanceolate; margins recurved; costa percurrent or excurrent; cells uniform throughout, ± quadrate, or longer towards base, smooth, unistratose. Inner perichaetial leaves with long sheathing base. Setae purplish red or yellow; capsules inclined, straight or curved, strumose, sulcate when dry; annulus of large cells; peristome teeth bifid into papillose filiform segments; calyptrae cucullate. Cosmopolitan, four species. Derivation: derived from the Greek for horn and tooth referring to the resemblance of a peristome tooth to an animal horn. For a monograph Of Ceratodon see J. S. Burley & N. M. Pritchard, Harvard Papers in Botany 2, 17–76, 1990.

Capsules inclined, strumose, peristome segments with pale margins, leaves often somewhat recurved when moist, margins often toothed near apex, calcifuge 1. C. purpureus Capsules ± erect, not or hardly strumose, peristome segments without pale margins, leaves straight, margins entire, calcicole 2. C. conicus 1 C. purpureus (Hedw.) Brid., Bryol. Univ., 1826 (Fig. 46) Tufts or patches ranging in colour from yellowish green to vinous or brownish red, to 3.5 cm high. Lower leaves closely appressed, ± straight, upper slightly twisted, flexuose when dry, erect-patent and often recurved when moist, ovate-lanceolate to linear-lanceolate, acute to acuminate, very rarely obtuse, channelled; margins ± recurved from base to apex, often bluntly toothed near apex; costa stout, percurrent or excurrent, in section c. 1.5 times as wide as thick; cells rectangular at base, becoming quadrate to irregularly hexagonal above, incrassate or not, smooth, pellucid, 9–12 μm wide in mid-leaf. Perichaetial leaves longer with expanded bases. Setae deep purplish red; capsules reddish brown, obloid, inclined to horizontal, curved, strumose, sulcate when dry; lid conical; peristome segments with pale margins from base to about middle, with 11–13(−16) articulations; spores 10–14 μm. Capsules common, spring, early summer. n = 13∗ . A primary coloniser on soil, rocks, walls, in a great variety of habitats, sometimes epiphytic, calcifuge. 0–1210 m. The most commonly found acrocarpous moss in the British Isles, pollution tolerant and occurring in urban and industrial areas. 112, H40, C. GB2120 + 192∗ , IR272 + 9∗ , C8 + 1∗ . Circumpolar Wide-boreal. Europe north to Svalbard, Caucasus, S. W, Asia, Himalayas, N. E. China, Japan, Korea, Macaronesia, N. America, Greenland. A highly polymorphic primary colonising species that may be found on almost any basepoor substrate. Usually easily recognised by the deep purple-red setae, the channelled

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Fig. 46 1–3, Saelania glaucescens: 1, leaves; 2, mid-leaf cells; 3, capsule (×10). 4–9, Ceratodon purpureus: 4, leaves; 5, basal cells; 6, mid-leaf cells; 7, costa section 1 /3 from leaf base; 8, capsule (×15); 9, peristome tooth. 10–13, C. conicus: 10, leaf; 11, costa section 1 /3 from leaf base; 12, capsule (×15); 13, peristome tooth. 14–16, Cheilothela chloropus; 14, leaf; 15, costa section 1 /3 from leaf base; 16, mid-leaf cells. Leaves ×21, sections ×300; cells ×420.

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leaves with stout costa, margins recurved almost to the apex and the smooth pellucid cells. There have been several literature reports of rhizoidal gemmae in C. purpureus but these are almost certainly erroneous (see H. L. K. Whitehouse, J. Bryol. 9, 177–84, 1976). Axillary green to pale brown filamentous, usually uniseriate propagules, 150–190 μm long, borne on older parts of the stem, have been reported from riparian habitats in N. America but I have been unable to find them on British material from similar situations. All British and Irish material belongs to ssp. purpureus, the other two subspecies occurring outside the British Isles.

2 C. conicus (Hampe) Lindb., Musci Scand., 1889 (Fig. 46) C. purpureus ssp. conicus (Hampe) Dixon, C. purpureus var. conicus (Hampe) Husn. Yellowish green tufts or patches, to 1 cm high. Leaves erect-patent, straight when moist, hardly altered when dry, forming comal tufts, ovate to ovate-lanceolate, acute; margins recurved ± from base to apex, entire; costa excurrent, sometimes longly so, in section relatively thin, about 3 times as wide as thick; basal cells rectangular, becoming quadrate above, incrassate, smooth, pellucid, 5–12 μm wide in mid-leaf. Setae orange-red; capsules ± erect, ellipsoid, not or hardly strumose, smooth or slightly sulcate when dry; lid conical; peristome segments without or with only very narrow pale margins in lower half, with 7–9(−12) articulations; spores 11–13 μm. Capsules occasional, spring. On thin dry soil, particularly over oolitic limestone, on tops of and in crevices of walls, on paths and in quarries, calcicole. Lowland. Rare and decreasing; seen recently only in Oxford, Berkshire and Warwick with old confirmed records from Northampton, E. Gloucester and S. Lincoln. 6. GB7 + 13∗ . Submediterranean-Subatlantic. Germany, Norway, Sweden, Alps, S. W. Asia, La Palma, Tenerife, N. Africa. C. conicus is readily distinguished from C. purpureus when capsules are present, but sterile plants may present problems and not all can be named. However, C. conicus is a calcicole, is usually yellowish green, has straight leaves, which are similar moist or dry, in a comal tuft and the costa relatively less thick than in C. purpureus. This species is considered endangered in the Red List of British mosses and this is because of the destruction of habitats, especially walls, where it occurs.

21 CHEILOTHELA (LINDB.) BROTH., NAT. PFLANZENFAM., 1901 Dioicous. Leaves increasing in size up stem, rigid when moist, ovate-lanceolate to triangular; costa well defined, excurrent; cells smooth at base of leaf, mamillose and bistratose above. Capsules similar to those of Ceratodon but not strumose. A mainly Southern Hemisphere genus of about 6 species. Derivation: meaning thick nipple, referring to the capsule beak.

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1 C. chloropus (Brid.) Broth., Nat. Pflanzenfam., 1901 Ceratodon chloropus (Brid.) Brid.

(Fig. 46)

Dull yellowish green sometimes extensive patches, to 1 cm high. Underground horizontal axes often present. Leaves appressed, straight when dry, erect-patent, rigid when moist, ± narrowly triangular to ovate, acuminate; margins plane, finely crenulate below, papillose-crenulate above; costa broad, excurrent in stout point; basal cells shortly rectangular, smooth, hyaline, cells above smaller, quadrate, mamillose, bistratose, very obscure, 6–8 μm wide in mid-leaf. Setae pale yellow; capsules ellipsoid, not strumose. Capsules not known in England. On thin soil overlying basic rock. Lowland. Very rare, S. Devon, N. Somerset. 2. GB4. Mediterranean-Atlantic. South-west and Mediterranean Europe, Turkey, Cyprus, Algeria, Macaronesia, southern Africa. C. chloropus is very unusual in that the vertical axes produce underground horizontal branches which ramify through the top 1 cm of soil forming an intricate network (see R. Porley, J. Bryol. 17, 164–6, 1992).

10 Bruchiaceae Leaves spirally arranged; alar cells not differentiated, cells above rectangular. Capsules dehiscent (Trematodon) or cleistocarpous (Bruchia), neck half or more total length of capsule with numerous stomata; peristome teeth bifid or perforated; annulus absent. Five genera.

22 TREMATODON MICHX., FL. BOR.-AMER., 1893 Autoicous. Leaves ± abruptly narrowed from sheathing base into acumen; costa excurrent. Capsules dehiscent, subclavate, slightly curved; peristome teeth ± entire to deeply bifid. A ± cosmopolitan genus of nearly 100 species. Derivation: meaning perforated tooth, referring to the peristome.

1 T. ambiguus (Hedw.) Hornsch., Flora, 1819 (Fig. 45) Green or brownish tufts, to 1 cm high. Leaves erect-patent when moist, from oblong or oblong-lanceolate sheathing basal part rapidly narrowed to long blunt acumen composed mainly of costa, acumen about 1/2 length of lamina in leaves from middle part of stem, shorter in upper and perichaetial leaves; margins plane, entire; costa stout, excurrent, obscurely toothed on abaxial side towards apex; basal cells of sheathing portion narrowly rectangular, narrower towards margins, shorter above, rectangular at shoulder, cells in acumen narrowly rectangular. Setae yellow, 1–3 cm long; capsules erect, slightly curved, neck about same length as capsule body, slightly strumose; spores 30–36 μm. Capsules common, summer. n = 13 + 2m. On moist peaty soil in montane areas. 350 m. Probably extinct, Mid

23 Rhabdoweisia

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Perth, 1883, not seen since. 1. GB1∗ . European Boreal-montane. N. and C. Europe, Iceland, Himalayas, Kamchatka, Japan, N. America. Although widely scattered in northern Europe this species has only been found once in the British Isles, although when capsules are present it is hardly likely to be overlooked.

11 Rhabdoweisiaceae Usually autoicous. Stems with or without central strand. Leaves spirally arranged, linear-lanceolate to ovate; alar cells differentiated or not, cells above quadrate, smooth or mamillose. Capsules erect, ovoid to ellipsoid, symmetrical or not, often longitudinally furrowed or sulcate when dry and empty; stomata present; annulus cells small; peristome teeth entire, perforated or deeply cleft, smooth or with oblique striations alternating in direction with each articulation; calyptrae cucullate. Eleven genera.

23 RHABDOWEISIA BRUCH & SCHIMP. IN BRUCH ET AL., BRYOL. EUR., 1846 Autoicous. Stems without central strand. Leaves crisped when dry, spreading when moist, narrowly linear-lanceolate to lingulate, acute to obtuse; margins plane or recurved below, toothed above; costa ending below apex; basal cells rectangular, alar cells not differentiated, cells above ± quadrate, slightly mamillose or not. Setae short; capsules erect, ovoid, striate; lid with oblique beak; peristome teeth entire, smooth or with oblique striations alternating in direction with each articulation. A small genus of 5 species occurring in Europe, E. and C. Asia, W. and C. Africa, Macaronesia and the Americas. Derivation: meaning fluted column, referring to the striate capsules.

1 Cells in upper part of leaf 12–20 μm wide, margins irregularly dentate 3. R. crenulata Cells in upper part of leaf 8–12(−14) μm wide, margins entire or denticulate above 2 2 Lamina 3–4(−5) cells wide on either side of costa 220 μm from apex, peristome teeth very narrow, fugacious 1. R. fugax Lamina 5–7 cells wide on either side of costa 220 μm from apex, peristome teeth lanceolate, not fugacious 2. R. crispata 1 R. fugax (Hedw.) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1846 (Fig. 47) Bright green or yellowish green tufts, 0.5–1.0 cm high. Leaves crisped when dry, flexuose-spreading when moist, ligulate or linear-lanceolate, gradually tapering to acuminate apex, lamina 6–9 cells wide on each side of costa at middle of leaf, 3–4(−5) cells wide 220 μm from apex; margins plane, entire or denticulate near

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Fig. 47 1–4, Rhabdoweisia fugax: 1, leaves; 2, cells at leaf apex; 3, capsule; 4, peristome tooth. 5–8. R. crispata: 5, leaves; 6, cells at leaf apex; 7, capsule; 8, peristome tooth. 9–11, R. crenulata: 9, leaves; 10, cells at leaf apex; 11, capsule. Leaves ×25, cells ×420, capsules ×15, teeth ×175.

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apex; costa ending below apex; basal cells rectangular, rounded-quadrate or wider than long above, 8–12 μm wide in upper part of leaf. Setae yellowish; capsules ovoid, longitudinally striate, contracted or not below mouth when dry; lid with oblique beak; peristome teeth very narrow from a broad base, fugacious; spores 14– 20(−22) μm. Capsules common, ± throughout year. n = 13. In shaded non-basic rock crevices in ravines, woods and on cliffs. 0–800 m. Frequent in N. W. Wales, occasional in other montane parts of Britain, rare in Ireland. 45, H11. GB125 + 22∗ , IR5 + 9∗ . European Boreal-montane. Europe, Faeroes, Caucasus, Macaronesia, S. Africa, Mexico, S. America. 2 R. crispata (Dicks. ex With.) Lindb., Acta Soc. Sci. Fenn., 1871 R. denticulata (Brid.) Bruch & Schimp.

(Fig. 47)

Bright yellowish green tufts, 0.5–1.5 cm high. Leaves crisped when dry, flexuosespreading when moist, narrowly lingulate to ligulate, abruptly to gradually tapering to acute to obtuse apex, lamina 6–12 cells wide on each side of costa in middle of leaf, 5–7 cells wide 220 μm from apex; margins plane or narrowly recurved below, denticulate towards apex; costa ending below apex; basal cells rectangular, cells above quadrate-hexagonal, 10–12(−14) μm wide in upper part of leaf. Setae yellowish; capsules ovoid, longitudinally striate when dry; lid with oblique beak; peristome teeth gradually tapering from base to apex; spores 18–20 μm. Capsules common, ± throughout year. n = 13, 13 + m∗ , 14. Shaded rock crevices, amongst rocks in ravines, rarely on peat, usually in acidic habitats but occasionally where basic. 0–950 m. Frequent or common in western Britain, rare to occasional in Ireland. 53, H18 GB172 + 24∗ , IR20 + 7∗ . Suboceanic Boreal-montane. Europe, Faeroes, Amur, China, Korea, Japan, Java, N. Africa, N. and S. America, Greenland, Hawaii. R. crispata is intermediate between the other two British species. R. crenulata differs in its usually larger size, and its wider more shortly pointed and more coarsely toothed leaves, although sometimes the only reliable character is cell size and leaf width near the apex. R. fugax has the leaves narrower near the apex and very narrow fugacious peristome teeth.

3 R. crenulata (Mitt.) H. Jameson, Rev. Bryol., 1890 (Fig. 47) Bright yellowish green or green tufts, cushions or patches, 1–3 cm high. Leaves crisped when dry, erect-patent to spreading or recurved when moist, narrowly lingulate, acute to obtuse, lamina 9–14 cells wide on either side of costa in middle of leaf, 6–10 cells wide 220 μm from apex; margins plane or narrowly recurved below, strongly irregularly dentate above; costa ending below apex; basal cells rectangular, cells above ± quadrate-hexagonal, sometimes wider than long, 12–20 μm wide in upper part of leaf. Setae yellowish; capsules ovoid or ovate-ellipsoid, longitudinally striate; lid with oblique beak; peristome teeth gradually tapering from base to apex; spores 18–24 μm. Capsules common, spring,

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summer. n = 13 + m∗ . In rock crevices and on damp rocks in sheltered nonbasic montane habitats, often by waterfalls. 0–800 m. Occasional to frequent in N. W. Wales, N. W. England and W. Scotland north to W. Sutherland, very rare in S. and Mid Wales, Cheshire, Durham, N. Northumberland, occasional in W. Ireland. 35, H15. GB89+15∗ , IR19+2∗ . Oceanic Boreal-montane. Belgium, Czechoslovakia, France, Germany, Norway, Spain, Switzerland, Sikkim, China, Taiwan, N. America, Greenland, Columbia, Hawaii.

24 OREOWEISIA DE NOT., ATTI REALE UNIV. GENOVA, 1869 Autoicous. Stems with central strand. Leaves incurved and crisped when dry, erect-patent to spreading when moist, linear-lanceolate; cells quadrate, mamillose. Capsules ± erect, ovoid, smooth when moist and when dry; annulus cells small, persisting. Derivation: meaning mountain Weissia.

1 O. bruntonii (Sm.) Milde, Bryol. Siles., 1860 Cynodontium bruntonii (Sm.) Bruch & Schimp.

(Fig. 49)

Dense dark green cushions or tufts, 1–3 cm high. Leaves strongly curled inwards when dry, erect-spreading with tips often recurved when moist, narrowly lanceolate, gradually tapering to acute apex; margins recurved to about half way up leaf, remotely crenulate-denticulate above; costa ending in or below apex, slightly rough on abaxial side above; basal cells rectangular, cells above quadrate, mamillose on both sides, partially bistratose, opaque, 7–14 μm wide in mid-leaf. Yellowish brown rhizoidal gemmae 50–90 μm long, consisting of unbranched or branched row of cells, sometimes present. Perigonial leaves subacute. Setae yellowish; capsules pale brown, erect, ovoid, smooth, ± symmetrical, slightly contracted at mouth, when dry sometimes slightly plicate; annulus persisting; lid entire at base; peristome teeth irregular, to 160 μm long, variously divided; spores 15–19 μm. Capsules frequent, late spring, early summer. n = 13∗ , 14∗ , 15∗ . In clefts and crevices of sheltered non-basic rocks and walls, in montane areas. 0–480 m. Occasional in western England, frequent in Mid and N. Wales, occasional in eastern Scotland, very rare elsewhere and in Ireland, Jersey. 64, H11, C. GB188 + 40∗ , IR8 + 6∗ , C1. European Temperate. Europe north to Svalbard, Iceland, Turkey, Azores, Canary Islands. Differs from Cynodontium species in capsule characters. When sterile it may be distinguished from C. polycarpon and C. strumiferum by the more densely tufted habit, the leaves strongly curled inwards when dry and the lower leaves smaller than the upper; the leaf cells are bistratose and opaque. It is more likely to be confused with Dicranoweisia cirrata, which, however, grows on exposed rather than sheltered rocks and walls as well as on trees. The presence of rhizoidal gemmae in O. bruntonii may also be a useful character.

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25 CYNODONTIUM BRUCH & SCHIMP. IN BRUCH ET AL., BRYOL. EUR., 1856 Autoicous. Lax or dense tufts. Leaves crisped when dry, erect-patent to spreading when moist, narrowly lanceolate, channelled; margins recurved to about half way, ± toothed above, often bistratose; costa ending at or just below apex or (in non-British species) excurrent; basal cells rectangular, shorter at margins, alar cells not or scarcely differentiated, cells above quadrate, thick-walled, slightly collenchymatous, smooth to conically mamillose. Setae long; capsules ± erect or inclined, straight or curved, usually striate, sometimes strumose; lid with long oblique beak; peristome teeth divided to half way or below, sometimes irregular and short, longitudinally striate below, papillose above. About 12 species occurring mainly in Europe. Derivation: meaning dog tooth, referring to the appearance of a peristome tooth of Cynodontium (Oreoweisia) bruntonii. This genus has been misunderstood in Britain. For an account of Cynodontium (including Oreoweisia bruntonii) see A. C. Crundwell, Trans Br. Bryol. Soc. 3, 706–12, 1960. The present account of the genus is based upon an unpublished manuscript by A. C. Crundwell.

1 Cells 11–22 μm wide in mid-leaf, smooth 2. C. jenneri Cells 9–14 μm wide in mid-leaf, smooth or mamillose 2 2 Leaf margins unistratose throughout 4. C. fallax Leaf margins bistratose above 3 3 Capsules inclined, curved, strumose 1. C. strumiferum Capsules ± straight, not or hardly strumose 4 4 Leaf cells distinctly mamillose especially on adaxial side, perigonial leaves ± acute, annulus separating, lid crenulate at base 3. C. polycarpon Leaves smooth or slightly mamillose with mamillae mainly on abaxial side, perigonial leaves obtuse, annulus persisting, lid entire at base 5. C. tenellum ¨ 1 C. strumiferum (Hedw.) Lindb., Ofvers F¨orh. Kongl. Svenska Vetensk-Akad., 1869 (Fig. 48) C. polycarpon var. strumiferum (Hedw.) Schimp. Dense green tufts, 1–4 cm high. Leaves somewhat crisped when dry, spreading, subsecund when moist, narrowly lanceolate, gradually tapering to acute apex; margins strongly recurved to middle of leaf or above, irregularly crenulatedenticulate above; costa ending in or below apex; basal cells rectangular, cells above quadrate, bistratose at margins, unistratose elsewhere, strongly mamillose on both sides, pellucid, 9–12 μm wide in mid-leaf. Perigonial leaves subacute. Setae yellowish; capsules oblong-ellipsoid, inclined, curved, striate, conspicuously strumose; lid crenulate at base; annulus of 3 rows large cells, separating; peristome teeth all of similar length, 300–400 μm long, divided to half way or below; spores

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Fig. 48 1–6, Cynodontium strumiferum: 1, dry shoot; 2, leaf (×20); 3, marginal cells at middle of leaf; 4, leaf margin section; 5, capsule; 6, peristome tooth. 7–12, C. polycarpon: 7, dry shoot; 8, leaf (×15); 9, marginal cells at middle of leaf; 10, leaf margin section; 11, capsule; 12, peristome tooth. 13–17, C. fallax: 13, leaf (×15); 14, marginal cells at middle of leaf; 15, leaf margin section; 16, capsule; 17, peristome tooth. 18–22, C. gracilescens: 18, leaf (×15); 19, marginal cells at middle of leaf; 20, leaf margin section; 21, capsule; 22, peristome tooth. Cells ×450, capsules ×10, teeth ×100.

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18–24 μm. Capsules common, early summer. n = 14, 15. On sheltered acidic rocks and in scree. (30−)350–600 m. Very rare, E. Perth, Angus, Aberdeen, E. Inverness, Skye, E. Ross. 7. GB8 + 5∗ . Circumpolar Boreo-arctic Montane. Europe north to Svalbard, Iceland, Caucasus, Siberia, N. America, Greenland. Plants without sporophytes cannot be distinguished from C. polycarpon but both species produce sporophytes freely and differ markedly in capsule form although in central Europe the distinction is less clear cut and some authorities treat C. strumiferum as a variety of C. polycarpon. C. strumiferum is the only British species with peristome teeth of equal length.

2 C. jenneri (Schimp.) Stirt., Ann. Scot. Nat. Hist., 1906 (Fig. 49) Dense or lax bright green tufts, 1–4 cm high. Leaves crisped when dry, erectspreading when moist, narrowly lanceolate, gradually tapering to acute apex; margins narrowly recurved to about half way up leaf, rarely plane, coarsely dentate to almost entire above; costa ending in or below apex, usually slightly toothed on abaxial side above; basal cells rectangular, cells above quadrate, unistratose throughout, smooth on both surfaces, pellucid, 11–22 μm wide in midleaf. Perigonial leaves ± acute. Setae yellowish; capsules erect, symmetrical, ellipsoid with long neck, striate, not or only slightly strumose; lid crenulate at base; annulus of 2 rows of large cells, separating; peristome teeth shorter on one side of capsule than on the other, 300–400 μm long; spores 18–24 μm. Capsules common, summer. n = 14. On sheltered acidic rocks or rock ledges, occasionally on soil in woodland. 0–730 m. Occasional in N. Wales, N. W. England and Scotland (mainly in the east and centre), extending north to Caithness and Orkney. 23. GB37 + 11∗ . Suboceanic Boreal-montane. Westphalia, Scandinavia, Newfoundland, Pacific N. America. May be recognised when sterile by the leaves with unistratose margins and the cells larger than in other Cynodontium species.

3 C. polycarpon (Hedw.) Schimp., Coroll. Bryol. Eur., 1856 (Fig. 48) Dense or lax green tufts, 2–4 cm high. Leaves crisped when dry, erect-spreading when moist, narrowly lanceolate, gradually tapering to acute apex; margins recurved to above half way up leaf, crenulate-denticulate above; costa ending in or below apex, slightly mamillose on abaxial side above; basal cells rectangular, cells above quadrate, bistratose at margins, unistratose elsewhere, mamillose, especially on adaxial side, pellucid, 8–14 μm wide in mid-leaf. Perigonial leaves acute. Setae yellowish; capsules ± erect, ellipsoid, neck short, not or scarcely strumose; lid crenulate at base; annulus of 3 rows of cells, separating; peristome teeth shorter on one side of capsule than on the other, 300–400 μm long, bifid to below middle; spores 20–25 μm. Capsules common, early summer. n = 14. Sheltered rocks in montane habitats. Ascending to 880 m. Very rare, Merioneth, N. Northumberland, Cumberland, Angus, S. Aberdeen, E. Inverness (old record). 6. GB5 + 2∗ . European Boreal-montane. Europe north to Svalbard, Iceland, Turkey, Caucasus, C. Asia, Japan, Canada (Northern Territories), Greenland.

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Fig. 49 1–6, Cynodontium jenneri: 1, dry shoot; 2, leaf; 3, marginal cells at middle of leaf; 4, leaf margin section; 5, capsule; 6. peristome tooth. 7–12, C. tenellum: 7, dry shoot; 8, leaf; 9, marginal cells at middle of leaf; 10, leaf margin section; 11, capsule; 12, peristome tooth. 13–19. Oreoweisia bruntonii: 13, dry shoot; 14, leaf; 15, marginal cells at middle of leaf; 16, leaf margin section; 17, capsule; 18, peristome teeth; 19, rhizoidal gemmae (×300). Shoots ×5, leaves ×15, capsules ×10, cells ×450, teeth ×150.

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4 C. fallax Limpr., Laubm. Deutschl., 1886 (Fig. 48) Dense or lax green tufts, 2–6 cm high. Leaves crisped when dry, erect-spreading when moist, narrowly lanceolate to linear-lanceolate, gradually tapering to acute apex; margins recurved to about half way, crenulate-denticulate above; costa ending in or below apex, strongly mamillose on abaxial side above; basal cells rectangular, cells above quadrate, bistratose at margins, unistratose elsewhere, with numerous pointed mamillae on adaxial side, smooth or mamillose on abaxial side, pellucid, cells 9–14 μm wide in mid-leaf. Perigonial leaves acuminate. Setae yellowish; capsules ± erect, almost symmetrical, ellipsoid, neck short, striate, not strumose; lid entire at base; annulus a single row of small persistent cells; peristome teeth shorter on one side of capsule than on the other, 250–350(−450) μm long, bifid to below half way and usually with slits and perforations below; spores 18– 23 μm. Capsules common, summer. On sheltered acidic rocks. The single British record is based upon a gathering from Glen Phee, Angus, made in 1868. 1. GB1∗ . Eurasian Boreal-montane. C. and E. Europe north to Svalbard, N. Asia east to the Altai. In N. Europe the leaf cells of C. fallax are mamillose on the adaxial side only but in central Europe the cells may also be mamillose on the abaxial side. A record of C. gracilescens (D. Weber & F. Mohr) Schimp. (Fig. 48, 18–22), based upon a single unlocalised gathering from Wales by Evans in 1821 is questionable and the species should be deleted from the British list.

5 C. tenellum (Bruch & Schimp.) Limpr., Krypt.-Fl. Schlesien, 1877 (Fig. 49) Dense green tufts, 1–3 cm high. Leaves crisped when dry, erect-spreading when moist, narrowly lanceolate, gradually tapering to acute apex; margins recurved to more than half way up leaf, irregularly crenulate-denticulate or rarely entire above; costa ending in or below apex, smooth or slightly roughened on abaxial side above; basal cells rectangular, cells above quadrate, bistratose at margins, elsewhere unistratose, smooth on adaxial side, smooth or slightly mamillose on abaxial side, pellucid, cells 7–12 μm wide in mid-leaf. Perigonial leaves obtuse. Setae yellowish; capsules ± erect and symmetrical, ellipsoid with short neck, striate, not strumose; lid entire at base, annulus of 2 rows of small cells, persisting; peristome teeth shorter on one side of capsule than on the other, 220–280 μm long, divided nearly to base; spores 16–20 μm. On sheltered acidic rocks and scree. 150–600 m. Rare, Berwick, Perth, Angus, Kincardine, S. Aberdeen, Moray, E. Inverness. 8. GB14+4∗ . Circumpolar Boreo-arctic Montane. C. and N. Europe north to Svalbard, Caucasus, N. America. Confused in the past with C. polycarpon from which it differs in the obtuse perigonial leaves, the upper cells smooth on the abaxial side, the persistent annulus and the peristome teeth divided nearly to the base.

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26 ONCOPHORUS (BRID.) BRID., BRYOL. UNIV., 1826 Autoicous. Leaves crisped when dry, spreading when moist, from ± sheathing basal part narrowed to lanceolate, acuminate limb; costa reaching apex or excurrent; basal cells rectangular, alar cells enlarged or not; cells above roundedquadrate to rectangular, ± smooth. Setae straight; capsules inclined, curved, gibbous, strumose, not striate when moist but often sulcate when dry; peristome teeth divided almost to base. A small genus of c. 13 species occurring in temperate and arctic regions, Sri Lanka and southern S. America. Derivation: the name refers to the goitre-like swelling at the capsule base.

Leaf margins recurved at least on one side, alar cells enlarged, sometimes forming auricles, capsules mostly 2–3 times as long as wide 1. O virens Leaf margins plane, alar cells not enlarged, capsules 1.5–1.7 times as long as wide 2. O. wahlenbergii 1 O. virens (Hedw.) Brid., Bryol. Univ., 1826 Cynodontium virens(Hedw.) Schimp.

(Fig. 50)

Dense tufts or patches, yellowish green above, brownish below, 2–9 cm high. Leaves flexuose to crisped when dry, spreading when moist, upper leaves longer than lower, ± reflexed, tapering from ovate or oblong sheathing basal part to narrowly lanceolate acuminate limb; margins recurved below at least on one side, entire or toothed above; costa percurrent or shortly excurrent; basal cells rectangular or narrowly rectangular, alar cells shorter, wider, 2–3-stratose, sometimes forming weak auricles, cells above rounded-quadrate, smooth, bistratose at margins, 8–12 μm wide in mid-leaf. Setae reddish; capsules inclined, ellipsoid, curved, strumose, smooth, 1.5–2.0 mm long, (1.5−)2.0–3.0 times as long as wide; lid with oblique beak; peristome teeth bifid; spores 20–28 μm. Capsules frequent, summer. n = 14. On damp ground, on wet rocks by streams and in flushes, in basic habitats. 640–970 m. Rare, Westmorland, Cumberland, Perth, Angus, S. Aberdeen, Inverness, Skye, Sutherland. 10, GB21 + 2∗ . Circumpolar Boreo-arctic Montane. Montane and northern Europe north to Svalbard, Faeroes, Iceland, Turkey, Caucasus, Himalayas, N. Asia, Morocco, California, Greenland. Differs from Cynodontium species in occurring in habitat and in the smooth strumose capsules. O. wahlenbergii differs in the shorter capsules and more narrowly pointed leaves which lack auricles.

2 O. wahlenbergii Brid., Bryol. Univ., 1826 Cynodontium wahlenbergii (Brid.) Hartm.

(Fig. 50)

Green or yellowish green tufts or patches, to 3 cm high. Leaves crisped when dry, patent when moist, upper leaves scarcely longer than lower, gradually or abruptly tapering from short sheathing basal part to lanceolate or linear-lanceolate

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Fig. 50 1–4, Oncophorus virens: 1, leaves; 2, alar cells (×320); 3, mid-leaf cells (×450); 4, capsule. 5–8, O. wahlenbergii: 5, leaves; 6, alar cells (×320); 7, mid-leaf cells (×450); 8, capsule. Leaves ×20, capsules ×10.

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acuminate limb; margins plane, denticulate towards apex; costa ending below apex to excurrent; basal cells rectangular, alar cells shorter but not enlarged, unistratose, cells above irregularly quadrate, incrassate, smooth, bistratose at margins above, 8–12 μm wide in mid-leaf. Setae reddish; capsules inclined, ovoid, curved, smooth, strumose, 1.2–1.7 mm long, 1.5–1.7 times as long as wide; lid with oblique beak; spores 20–28 μm. Capsules frequent, summer. n = 14. Damp rocky hillsides and by streams and springs. 700–1000 m. Rare, Mid Perth, S. Aberdeen, W. Inverness, Argyll, Skye, E. Ross, old records from E. Perth, Dunbarton, and W. Ross. 10. GB12 + 6∗ . Circumpolar Boreo-arctic Montane. Montane and northern Europe north to Svalbard, Caucasus, Himalayas, E. Asia, Arizona, Greenland.

27 DICHODONTIUM SCHIMP., COROLL. BRYOL. EUR., 1856 Plants forming tufts or patches; stems with central strand. Leaves narrowly lanceolate to ovate, acute to obtuse; margins usually dentate; cells in upper part of leaf mamillose and often opaque, rounded-quadrate. Capsules ovoid to cylindrical, straight or curved, smooth; annulus lacking; peristome teeth divided and papillose above, pitted -striate below; calyptrae cucullate. Six species occurring in Europe, Asia, America, New Zealand. Dervation: Referring to the peristome teeth split in two.

1 Leaves squarrose when moist, cells smooth, pellucid 3. D. palustre Leaves spreading to reflexed when moist, cells coarsely mamillose, usually opaque 2 2 Capsules curved, 1–2 times as long as wide, leaves 2.4–3.9 times as long as wide 1. D. pellucidum Capsules straight or nearly so, ± erect, 2–4 times as long as wide, leaves 4.0–5.5 times as long as wide 2. D. flavescens

1 D. pellucidum (Hedw.) Schimp., Coroll. Bryol. Eur., 1856 (Fig. 51) Lax, dull or light green tufts or patches, to 7 cm high. Leaves incurved when dry, spreading to sharply reflexed when moist, 2.4–3.9 times as long as wide, lanceolate to ovate from broad basal part, widest c. 1 /5 from base, acute to obtuse; margins recurved below, serrulate to coarsely dentate, sometimes undulate above; costa stout, 60–100 μm wide near base, strongly toothed on abaxial side above, teeth 12–14 μm wide; cells incrassate, sometimes opaque above, lower narrowly rectangular, becoming smaller and moderately to coarsely mamillose above, mamillae concealing lumens, ± quadrate from mid-leaf in ovate-leaved forms, towards apex in narrow-leaved forms, 8–10 μm wide in mid-leaf, marginal cells above similar to other cells. Brown globular ellipsoid or clavate, several-celled gemmae, 60–100 μm long, on filamentous branches arising below leaf insertions, occasionally produced. Setae straight, thick, yellow; capsules inclined, ovoid to

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Fig. 51 1–5, Dichodontium pellucidum: 1, leaves (×15); 2, basal cells; 3, mid-leaf cells; 4, capsule; 5, gemmae (×300). 6–8, D. flavescens: 6, leaf (×15); 7, mid-leaf cells; 8, capsules. 9–10, Aongstroemia longipes: 9, leaves (×25); 10, mid-leaf cells. Cells ×420, capsules ×15.

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ellipsoid, curved, smooth, 1.5–3.0 times as long as wide excluding lid; lid rostrate, less than half length of capsule; spores 10–12 μm. Capsules occasional, autumn to spring. n = 14∗ , 14 + m. On gravelly soil, sand and rocks by streams and rivers, on damp soil and on dune-slacks, often but not necessarily where there is some base, rarely in limestone grassland. Very rare in most of lowland England although frequent in the south-east, common elsewhere, frequent in the west of Ireland, rare to occasional elsewhere. 99, H33. GB1017 + 91∗ , IR57 + 4∗ . Circumpolar Boreoarctic Montane. Europe north to Svalbard, Faeroes, Iceland, Turkey, Siberia, China, Japan, Madeira, Algeria, Colorado. An extremely variable species. Distinguished from D. flavescens when sporophytes are present by the shorter inclined or curved capsules. When sterile it may be distinguished by the relatively wider leaves, more strongly papillose cells and the upper marginal cells of similar size to other cells. D. flavescens is regarded by some authorities as a variety of or synonymous with D. pellucidum. Thus, Nyholm (1987) says that plants with straight and curved capsules occur in the same tuft. However, examination of herbarium specimens showed capsule differences to be consistent. This is born out by recent observation by J. Werner, J. Bryol. 24, 215–21, 2002. Both Werner’s observations and mine were made on herbarium material rather than random field gatherings and the dangers of using only such material when coming to taxonomic conclusions must be borne in mind. Plants with small sharply reflexed ovate leaves have been named var. fagimontanum (Brid.) Schimp., but because of the large number of intermediates the variety is not recognised here. Stunted forms of D. pellucidum may be mistaken for Leptodontium flexifolium but that species differs in the shorter basal cells, rounded-hexagonal upper cells and the row of pale marginal cells near the leaf base. Gemmae are only occasionally produced but when present may be so abundant as to render the plants dusty in appearance. For a description of the gemmae see M. E. Newton, J. Bryol. 15, 806–8, 1989.

2 D. flavescens (Dicks. ex With.) Lindb., Bot. Not., 1879 D. pellucidum var. flavescens (Dicks. ex With.) Kindb.

(Fig. 51)

Yellowish to dark green tufts or patches, to 7 cm high. Leaves lanceolate from wide erect basal part, widest near base, acute to obtuse, 4.0–5.5 times as long as wide; margins irregularly toothed to coarsely toothed; costa stout, ending below apex, 55–110 μm wide near base, teeth on abaxial side 10–12 μm wide; cells incrassate, lower narrowly rectangular, becoming ± quadrate towards the apex, mamillose, mamillae not covering lumen, 8–10 μm wide in mid-leaf, upper marginal cells larger than other cells. Gemmae similar to those of D. pellucidum very rarely produced. Capsules ± erect, narrowly ellipsoid to cylindrical, straight, smooth, 12– 4 times as long as wide excluding lid; lid more than half length of capsule; spores 20–24 μm. Capsules autumn to spring. n = 7∗ , 14. In similar habitats to D. pellucidum. Mainly at low altitudes. Rare in western and northern Britain, Dublin,

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Wicklow, Antrim, Londonderry (but many records require confirmation). 27, H4. GB10 + 30∗ , IR1 + 3. Belgium, France, Italy, Luxembourg, Spain, Caucasus, British Columbia. 3 D. palustre (Dicks.) M. Stech, Nova Hedwigia, 1999 (Fig. 52) Anisothecium palustre (Dicks.) I. Hagen, Dicranella palustris (Dicks.) Crundw. & E. F. Warb., Dicranella squarrosa (Schrad.) Schimp. Dioicous. Yellowish green to bright green tufts or patches, 1–10(−15) cm high. Leaves squarrose when moist, basal part oblong, sheathing, decurrent, gradually tapering to squarrose oblong-lanceolate limb, apex obtuse; margins plane, crenulate or rarely entire above; costa thin, ending well below apex, cells in sheathing basal part narrowly rectangular or narrowly rhomboidal, hyaline, in limb gradually becoming smaller, irregular in shape and more incrassate, smooth, rectangular, 8–12 μm wide in mid-leaf. Spherical reddish brown or brown rhizoidal gemmae, 200–250 μm diameter, often present. Setae purple; capsules ovoid, inclined, gibbous, smooth; lid with oblique beak; spores 16–22 μm. Capsules rare, autumn to spring. n =15∗ . In marshes, flushes, springs, at edges of small streams. 0–1100 m. Almost absent from lowland England, common elsewhere. 93, H32. GB714 + 57∗ , IR104 + 9∗ . European Boreal-montane. Europe north to Svalbard, Faeroes, Iceland, Caucasus, Turkey, Japan, N. America, Greenland. Although usually placed in Dicranella, DNA studies show that this species is closely related to D. pellucidum (see M. Stech, Nova Hedwigia 69, 237–40, 1999). Stunted forms may be confused with D. pellucidum, which, however, differs in toothed leaves and strongly mamillose obscure cells.

28 DICRANOWEISIA LINDB. IN MILDE, BRYOL. SILES., 1869 Autoicous. Plants forming dense tufts or cushions; stems with central strand. Leaves crisped when dry, patent to spreading when moist, from ovate or lanceolate basal part abruptly narrowed or gradually tapering to apex; margins plane or recurved; costa ending below apex; alar cells enlarged or not, cells above quadrate or rectangular, mamillose or smooth. Setae straight; capsules erect, symmetrical, smooth; peristome teeth deeply inserted; entire or bifid at tips. Twenty-four species occurring in temperate, arctic, antarctic and tropical montane regions. Derivation: a combination of Dicranum and Weissia.

Leaves with recurved unistratose margins, auricles absent, mid-leaf cells 12–14 μm wide, capsules narrowly ellipsoid to subcylindrical 1. D. cirrata Leaf margins plane, bistratose above, at least some leaves with distinct brownish auricles, mid-leaf cells 6–8(−10) μm wide, capsules ovate-ellipsoid 2. D. crispula

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Fig. 52 1–3, Dichodontium palustre: 1, leaves (×12.5); 2, mid-leaf cells; 3, capsule (×15). 4–7, Dicranoweisia crispula: 4, leaf (×25); 5, basal cells; 6, mid-leaf cells; 7, capsule. 8–12, D. cirrata: 8, leaf; 9, basal cells; 10, mid-leaf cells; 11, capsule; 12, gemmae (×280). Cells ×420, capsules ×15.

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1 D. cirrata (Hedw.) Lindb. in Milde, Bryol. Siles., 1869 (Fig. 52) Yellowish green to green tufts or cushions, 0.5–3.0 cm high. Leaves strongly crisped and incurved when dry, erect-patent to spreading when moist, lower lanceolate, upper narrowly lanceolate, gradually tapering to acute apex; margins entire, recurved at middle of leaf; costa ending below apex; basal cells rectangular, (9−)12–18 μm wide, alar cells shorter and wider but not forming auricles, cells above quadrate or rounded-quadrate, smooth, pellucid, unistratose at margins, 10–14 μm wide in mid-leaf. Ellipsoid to cylindrical gemmae, to 150 μm long, often present and sometimes abundant on adaxial side of leaves near leaf base. Setae yellow; capsules narrowly ellipsoid to subcylindrical; lid obliquely rostrate; spores 12–20 μm. Capsules common, autumn to spring. n = 11, 11 + m, 13∗ , 14. On bark, thatch, rocks and walls, tolerant of some degree of pollution and occurring in urban and industrial areas, calcifuge. 0–625 m. Common at low altitudes, rare in northern Scotland and Ireland. 109, H19, C. GB1473 + 96∗ , IR30 + 16∗ , C1 + 2∗ . European Temperate. Europe, Faeroes, Turkey, Cyprus, Caucasus, Himalayas, Mongolia, Macaronesia, N. Africa, N. America, Tasmania, Hawaii. Only likely to be confused with Oreoweisia bruntonii (q.v.) and Dicranum montanum (q.v.). One of the few mosses that seems to be increasing, possibly because acidification of substrates reduces competition from other more pollution susceptible species.

2 D. crispula (Hedw.) Milde, Bryol. Siles., 1869 (Fig. 52) Yellowish green to green or sometimes blackish tufts or cushions, 1–3 cm high. Leaves crisped, incurved when dry, flexuose-spreading, sometimes secund when moist, from ovate or lanceolate basal part abruptly narrowed or gradually tapering to linear acuminate limb; margins plane, entire; costa shortly excurrent; basal cells linear, 6–8 μm, alar cells enlarged or inflated and forming auricles, becoming brownish with age in most leaves, cells above irregularly quadrate, smooth, pellucid, bistratose at margins, 6–8(−10) μm wide in mid-leaf. Setae yellow; capsules ovate-ellipsoid; spores 12–20 μm. Capsules common, spring, summer. n = 11, 14. On exposed siliceous, rarely basic rocks, on stony soil. (60−)300–1335 m. Cornwall, Devon, Caernarfon, Yorkshire, Lake District, frequent in the central Scottish Highlands, rare elsewhere in Scotland. 24. GB45 + 11∗ . Circumpolar Boreoarctic Montane. Montane and northern Europe north to Svalbard, Faeroes, Iceland, Turkey, Caucasus, Himalayas, Siberia, Japan, Morocco, N. America, Greenland, Peru.

12 Dicranaceae Plants small to large. Stems with central strand, often tomentose. Leaves usually of ± uniform size up stems, straight to falcate, narrowly to broadly lanceolate, usually acuminate; costa ending below apex to excurrent, in section with stereids; cells often porose, basal elongate, alar cells often differentiated, cells above quadrate to elongate, smooth or mamillose. Setae usually long, straight to cygneous; capsules

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ovoid to cylindrical, straight or curved, sometimes strumose, very rarely cleistocarpous; peristome teeth 16, well developed, deeply bifid, papillose above, pittedstriolate below; calyptrae cucullate. About 50 genera. Subfamily 1 ANISOTHECIOIDEAE Plants usually small. Leaves lanceolate, acuminate; without differentiated alar cells, cells smooth. Capsules erect or inclined, straight or curved, sometimes strumose, smooth or striate; peristome teeth divided to about midway, papillose above.

29 AONGSTROEMIA BRUCH & SCHIMP. IN BRUCH ET AL., BRYOL. EUR., 1846 Dioicous. Plants small. Leaves imbricate, ovate with wide base, obtuse to acute; costa thin; cells lax, thin-walled. Perigonia and perichaetia bud-like with leaves larger, more acute and with stronger costa than stem leaves. Capsules erect, ovoid; lid obliquely rostrate; peristome teeth entire or irregularly cleft to midway. A mainly tropical genus with about 17 species. ¨ (1813–1879). Derivation: named after the Swedish botanist J. Ångstrom

1 A. longipes (Sommerf.) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1846 (Fig. 51) Dense, bright green tufts, patches or scattered shoots, 10(−15) mm high; stems innovating from below inflorescences. Leaves imbricate when wet and when dry, difficult to detach from fragile stems, concave, ovate-oblong, obtuse; margins plane, entire; costa ending below apex; cells rectangular, thick-walled, decreasing in size from costa to margins, shorter and smaller towards apex, in mid-leaf 10–15 μm wide. Perigonia and perichaetia swollen, bud-like, bracts larger than stem leaves, tapering to blunt or acute apex, costa stouter, ending in apex. Vegetative propagation by fragile stems. Setae red; capsules erect, ± ovoid; spores 15–20 μm. Capsules rare, summer. On damp sandy soil in open habitats below dams, in quarries, on gravel by rivers, where slightly basic. Ascending to 400 m. Very rare, Mid and E. Perth, Moray, Inverness, Argyll, Dunbarton, Islay, W. Ross. 8. GB10. Circumpolar Boreal-montane. Northern and central Europe north to Svalbard, Iceland, Siberia, N. America, Greenland. Somewhat resembling Pohlia filum in general appearance but differing in the obtuse leaves, areolation and lack of axillary bulbils. For the occurrence of this plant in Scotland see A. C. Crundwell, Trans. Br. Bryol. Soc. 4, 67–74, 1965.

¨ 30 DICRANELLA (MULL. HAL.) SCHIMP., COROLL. BRYOL. EUR., 1856 Usually dioicous. Leaves narrow, differentiated into sheathing base and acuminate limb or gradually tapering from insertion, ± secund or squarrose; margins usually plane, entire or denticulate above; costa ending apex to excurrent; cells

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rectangular, smooth, alar cells not differentiated. Setae straight; capsules inclined, symmetrical or gibbous, sometimes strumose; annulus present or not; peristome teeth reddish, 16, bifid or divided to about middle into flat segments, papillose above, point-striate below; calyptrae cucullate. About 100 mainly terrestrial species, cosmopolitan. Derivation: meaning diminutive Dicranum. Many authorities recognise two genera, Dicranella and Anisothecium Mitt., but the latter is not recognised here as it separates closely related species.

1 Costa occupying 1/3 or more width of leaf base, setae yellow at maturity (becoming brown with age) 2 Costa occupying up to 1/5 width of leaf base, setae red to purple (but becoming brown with age) 3 2 Capsules strumose, leaf margins entire or finely denticulate towards apex, basal cells 70–115 μm long 8. D. cerviculata Capsules not strumose, leaf margins denticulate above, basal cells 30–50 μm long 9. D. heteromalla 3 Leaves squarrose or reflexed from erect sheathing base 4 Leaves ± erect-spreading to secund 6 4 Capsules suberect, symmetrical, cells in mid-leaf 4–6 μm wide 3. D. crispa Capsules inclined, gibbous, mid-leaf cells 6–14 μm wide 5 5 Leaf margins usually denticulate above, mid-leaf cells 8–14 μm wide, capsules smooth 1. D. schreberiana Leaf margins usually entire, mid-leaf cells c. 6 μm wide 2. D. grevilleana 6 Leaves abruptly narrowed or gradually tapering from erect sheathing basal part, capsules striate 7. D. subulata Leaves gradually tapering ± from insertion, basal part not sheathing, capsules smooth 7 7 Plants usually reddish tinged, leaf margins plane, capsules ± erect 6. D. rufescens Plants greenish, leaf margins narrowly recurved below, capsules erect or inclined 8 8 Upper leaves linear-lanceolate, mid-leaf cells 4–9 μm wide, perichaetial leaves similar in shape to stem leaves, capsules inclined, common 4. D. varia Upper leaves lanceolate, mid-leaf cells 10–14 μm wide, perichaetial leaves from sheathing basal part abruptly narrowed to long acumen, capsules erect, unknown in the British Isles 5. D. staphylina

Section 1 Dicranella (Mull.) ¨ Nyholm, Ill. Fl. Nord. Mosses, 1987 Stem and perichaetial leaves ± similar in shape but perichaetial leaves larger. Rhizoidal gemmae often present. Setae red; exothecial cells parenchymatous, stomata present; lid narrowly conical or ± obliquely rostrate

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1 D. schreberiana (Hedw.) Hilfarty ex H. A. Crum & L. E. Anderson, Mosses E. N. Amer., 1981 (Fig. 53) Anisothecium schreberianum (Hedw.) Dixon, D. schreberi (Hedw.) Schimp. Dioicous. Yellowish green patches or scattered plants, 3–10(−30) mm high. Leaves loosely crisped when dry, squarrose-flexuose when moist, from oblong sheathing basal part abruptly narrowed to lanceolate, acuminate limb; margins plane, denticulate at least towards apex, rarely entire; in taller forms leaves shorter, wider, less sharply reflexed, margins more strongly toothed; costa thin, ending in or below apex; cells in basal part rectangular to narrowly rectangular, in limb shorter, narrower, ± irregular in shape, 8–14 μm wide in mid-leaf. Brown to reddish brown ± spherical gemmae, 90–140 μm. Setae purple; capsules inclined, ovoid, gibbous, not strumose, smooth; exothecial cells with longitudinal walls more heavily thickened than transverse walls; lid with conical to acuminate beak; spores 12–16 μm. Capsules frequent, autumn to winter. n = 7, 14, 14 + m. On damp heavy often calcareous soil in fields, gardens, on woodland rides, ditch banks, moorland. Lowland. Common in lowland areas, rare elsewhere. 105, H36 C. GB688 + 85∗ , IR59 + 8∗ , C1 + 1∗ . Circumpolar Boreo-temperate. Europe north to Fennoscandia, Iceland, Caucasus, Siberia, Korea, Azores, N. America, Australasia. May occur with Ditrichum cylindricum but that plant has the costa longly excurrent and denticulate all the way round, not just on the margins.

2 D. grevilleana (Brid.) Schimp., Coroll. Bryol. Eur., 1856 Anisothecium grevilleanum (Brid.) H. Arnell & C. E. O. Jensen

(Fig. 53)

Dioicous or autoicous. Yellowish green tufts, 3–8 mm high. Leaves loosely crisped when dry, squarrose-flexuose when moist, from oblong sheathing basal part abruptly narrowed to channelled acumen; margins entire or obscurely denticulate near apex; costa thin, percurrent; basal cells narrowly rectangular, cells above ± rectangular, c. 6 μm wide in mid-leaf. Spherical brown or reddish brown rhizoidal gemmae, 90–140 μm diameter, sometimes present. Setae purple; capsules inclined, ovoid, slightly curved, very slightly strumose, faintly striate when dry; exothecial cells with uniformly thickened walls; lid with long beak; spores 12–22 μm. Capsules frequent, late summer, early autumn. n = 15. On disturbed damp basic soil on rock ledges, banks and in old quarries. Rarely below 380 m. Very rare, Mid and E. Perth, Argyll, E. Ross, W. Sutherland, Wicklow (not seen recently), Sligo, Antrim. 5, H3. GB7 + 1∗ , IR3 + 1∗ . Circumpolar Boreal-montane. Montane and northern Europe north to Svalbard, Iceland, Caucasus, China, N. America. Differs from D. schreberiana in its montane habitat, smaller leaf cells and the cells of the exothecium with uniformly thickened walls.

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Fig. 53 1–3. Dicranella schreberiana: 1, leaves (×40); 2, mid-leaf cells; 3, capsule. 4–6, D. grevilleana: 4, leaves (×40); 5, mid-leaf cells; 6, capsule. 7–9, D. subulata: 7, leaves (×25); 8, mid-leaf cells; 9, 10, capsules. Cells ×420, capsules ×15.

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3 D. crispa (Hedw.) Schimp., Coroll. Bryol. Eur., 1856 Anisothecium vaginale (Dicks. ex With.) Loeske

(Fig. 54)

Dioicous or autoicous. Yellowish green to green tufts, 5–10 mm high. Leaves loosely crisped when dry, squarrose-flexuose when moist, basal part oblong, sheathing, abruptly narrowed to long channelled linear acuminate limb; margins plane, entire below, erect or inflexed above, entire or denticulate towards apex; costa thin, ending in apex to excurrent, occupying most of acumen; cells in basal part linear to rectangular or rhomboidal, above very narrow, linear, 4–6 μm wide. Setae reddish brown; capsules erect, ellipsoid or obovoid, ± symmetrical, striate when dry; lid with long oblique beak; spores 16–20(−26) μm. Capsules common, autumn to winter. n = 14, 15. In open habitats on disturbed soil on banks by ditches, streams, rivers and roadsides, vertical sandstone rocks and dune-slacks. 0–550 m. Widely distributed but rare in Britain, very rare in Ireland. 44, H10. GB28 + 40∗ , UR4 + 7∗ . Circumpolar Boreo-arctic Montane. Europe north to Svalbard, Faeroes, Iceland, Siberia, N. America, Greenland.

4 D. varia (Hedw.) Schimp., Coroll. Bryol. Eur., 1856 Anisothecium varium (Hedw.) Mitt.

(Fig. 54)

Dioicous. Lax or dense bright or yellowish green tufts, patches or scattered plants, 2–10(−30) mm high. Leaves rigid, straight to slightly secund when dry, erectpatent, sometimes slightly secund when moist, basal part not sheathing, upper leaves linear-lanceolate, gradually tapering from insertion to acuminate apex, lower leaves shorter and wider; margins usually narrowly recurved, entire or slightly denticulate near apex; costa ending in apex to slightly excurrent, c. 55– 85(−100) μm wide near base, in section with scattered stereids on adaxial side and with 2 rows of guide cells; basal cells rectangular, incrassate, smaller near margins, cells above narrowly rectangular to linear, unistratose throughout, 4–9 μm wide in mid-leaf. Perichaetial leaves similar in shape to stem leaves, subsecund, margins denticulate. Irregular pale brown rhizoidal gemmae, 100–140(−250) × 60– 95 μm, often present. Setae purplish brown; capsules inclined, ovoid, gibbous, smooth when dry; exothecial cells with straight longitudinal walls more heavily thickened than transverse walls; lid conical or shortly beaked; spores 24–28 μm. Capsules common, autumn to spring. n = 7, 14∗ , 15. In open habitats, on damp, usually basic soil on roadsides, ditch banks, in fields, quarries, on heavy-metal mine waste. 0–490 m. Occasional in Scotland, frequent or common elsewhere. 111, H40, C. GB1128 + 89∗ , IR193 + 5∗ , C2 + 1∗ . Circumpolar Boreo-temperate. Europe north to Svalbard, Faeroes, Iceland, Turkey, Cyprus, Siberia, Kashmir, Yunnan, Macaronesia, N. Africa, N. America south to Guatemala, Cuba, Jamaica, Hawaii. A curious form, referred to as var. callistoma (With.) Schimp., occurs occasionally. The setae are very short, the capsules erect, symmetrical, very small but with normal size lids; the

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Fig. 54 1–3, Dicranella crispa: 1, leaves (×25); 2, mid-leaf cells; 3, capsule. 4–5, Plant intermediate between D. varia and D. howei: 4, leaves (×40); 5, exothecial cells. 6–11, D. varia: 6, leaves (×40); 7, mid-leaf cells; 8, rhizoidal gemmae (×175); 9, normal capsule; 10, capsule, possibly of apogamous origin, from plant referred as var. callistoma; 11, exothecial cells. Cells ×420, capsules ×15.

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spores are shrunken. The plant possibly has apogamous or hybrid sporophytes but cannot be considered a variety in the true sense of the word. D. rufescens differs in its usually reddish tinge, the leaves with plane denticulate margins and larger cells, and the erect capsules with uniformly thickened exothecial cell walls. A closely related species, D. howei Renauld & Cardot occurs in southern Europe (see A. C. Crundwell & E. Nyholm, Lindbergia 4, 34–8, 1977). This differs from D. varia in the usually plane leaf margins, the costa 85–100 μm wide near the base and occupying about 1/3 the width of the leaf base, and in section with only a single row of guide cells. The longitudinal walls of the exothecial cells are slightly sinuose and hardly thicker than the transverse walls. This plant has not been detected in the British Isles, but plants with sporophytes intermediate between those of the two species, possibly of hybrid origin, have been found in Caernarfon and it is very possible that D. howei occurs in Britain.

5 D. staphylina H. Whitehouse, Trans. Brit. Bryol. Soc., 1969 Anisothecium staphylinum (H. Whitehouse) Sipman et al.

(Fig. 55)

Dioicous. Dense bright green tufts or scattered plants, to 1 cm high. Leaves erect when dry, erect-patent to spreading, rarely secund when moist, lanceolate, tapering to acute apex; margins plane or recurved below, with a few obscure teeth towards apex; costa thin, ending below apex; cells ± rectangular, 10–14 μm wide in mid-leaf. Perichaetial leaves with sheathing basal part, abruptly narrowed to long flexuose or squarrose limb, not secund. Brownish rhizoidal gemmae, irregular in shape but often ± isodiametric, 50–100 × 50–80 μm always present. Setae bright yellow to orange (probably red at maturity); capsules erect; lid rostrate with slightly oblique beak; spores 15–18(−20) μm. Capsules unknown in the British Isles. On disturbed soil in fields, gardens, bare patches in grassland, gravel pits, by paths and roads, on banks and woodland rides. Lowland. Common in England and Wales, rare to occasional in Scotland, rare in Ireland. 108, H23, C. GB231, IR24 + 1∗ , C4. European Temperate. Europe north to Finland, Faeroes, Tenerife, Canada. Somewhat similar to D. varia and D. rufescens and more closely related to the former, which differs in the narrower more secund leaves, stronger costa, narrower cells and perichaetial leaves similar to stem leaves. D. rufescens is usually reddish, has longer narrower secund leaves with plane more obviously toothed margins, perichaetial leaves similar to stem leaves and most particularly the reddish coloration of the older parts of the plants. In D. staphylina the gemmae are constantly present but they are usually only present in senescing plants of D. rufescens and D. varia. For an account of this plant see H. L. K. Whitehouse, Trans. Br. Bryol. Soc. 5, 757–65, 1969. The description of the sporophyte was taken from T. Arts, Lindbergia 11, 55–9, 1985.

6 D. rufescens (With.) Schimp., Coroll. Bryol. Eur., 1856 Anisothecium rufescens (With.) Lindb.

(Fig. 55)

Dioicous. Yellowish green, usually strongly red-tinged tufts, patches or scattered plants, 3–8(−10) mm high. Leaves erect or flexuose-secund when dry, secund

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Fig. 55 1–4, Dicranella rufescens: 1, leaves (×40); 2, mid-leaf cells; 3, capsule; 4, rhizoidal gemmae (×250). 5–7, D. staphylina: 5, leaves (×63); 6, mid-leaf cells; 7, rhizoidal gemmae (×250). 8–11, D. cerviculata: 8, leaves (×25); 9, cells near leaf base; 10, cells from upper part of leaf; 11, capsule. Cells ×420, capsules ×15.

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when moist, narrowly lanceolate, base not sheathing, gradually tapering from near base to acuminate apex; margins plane, denticulate at least above; costa thin, ending in apex to excurrent; basal cells irregularly narrowly rectangular, cells above smaller, 8–14 μm wide in mid-leaf. Perichaetial leaves similar to upper stem leaves, flexuose-secund. Red moniliform rhizoidal gemmae, composed of 2(−4) cells, each cell 70–100 μm diameter, sometimes present, especially in senescing plants. Setae deep red; capsules erect, ellipsoid, symmetrical, smooth; exothecial cells with uniformly thickened walls; lid with oblique beak; spores 12–16 μm. Capsules occasional to frequent, autumn to spring. n = 10, 11∗ , 14. On usually fine damp acidic soil by streams, pools, beds of dried-out reservoirs, paths and occasionally woodland rides. 0–450 m. Frequent in southern England but very rare elsewhere in lowland England, frequent or common in other parts except N. E. Scotland, occasional in Ireland. 102, H28, C. GB532 + 66∗ , IR51 + 12∗ , C1 + 1∗ . Circumpolar Boreo-temperate. Europe north to Fennoscandia, Iceland, Turkey, Caucasus, Japan, Madeira, N. America. Readily recognised by its small size, reddish colour, regularly secund leaves and erect capsules.

Section 2 Pseudodicranella (Mull. ¨ Hal.) Nyholm, Ill. Fl. Nord. Mosses, 1987 Stem leaves tapering from ± ovate-lanceolate basal part. Perichaetial leaves with broad sheathing basal part ± abruptly narrowed into acuminate point. Setae red or yellow; exothecial cells prosenchymatous, stomata present or not; lid with subulate, often oblique beak. 7 D. subulata (Hedw.) Schimp., Coroll. Bryol. Eur., 1856 D. curvata (Hedw.) Schimp., D. secunda Lindb.

(Fig. 53)

Dioicous. Yellowish green to dark green tufts, 5–20 mm high. Leaves erect to curved or secund when dry, erect-patent or more usually secund when moist, basal part sheathing, oblong, gradually tapering or abruptly narrowed to long channelled acumen; margins plane below, erect or incurved above, towards apex entire or denticulate; costa thin, excurrent; cells in basal part narrowly rectangular, above linear, 4–6 μm wide in mid-leaf. Perichaetial leaves sheathing or not. Dark brown rhizoidal gemmae, 110–170 × 95–150 μm, often present. Setae reddish purple to brownish purple; capsules ovoid, erect and symmetrical to inclined and gibbous, striate or sulcate when dry; lid with long acuminate beak; spores 16–20 μm. Capsules common, autumn, winter. n = 13∗ , 14, 14 + m. On disturbed sandy or stony ground in turf, on banks by roads and streams, on damp sandstone and in sandstone quarries. 0–1050 m. Very rare in lowland Britain, occasional elsewhere, rare in Ireland. 64, H11. GB120 + 45∗ , IR4 + 6∗ . Circumpolar Boreo-arctic Montane. Europe north to Svalbard, Faeroes, Iceland, Turkey, Caucasus, Siberia, China, California, Greenland.

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8 D. cerviculata (Hedw.) Schimp., Coroll. Bryol. Eur., 1856 (Fig. 55) Dioicous. Yellowish green to green patches, 5–20 mm high. Leaves flexuose when dry, erect-patent to secund when moist, basal part half-sheathing, ovate to oblong, gradually or rapidly tapering to long channelled acumen, lower leaves smaller, more gradually tapering; margins plane below, erect or reflexed above, entire or finely denticulate towards apex; costa stout, 1/3 –1/2 width of leaf base, excurrent in entire or denticulate point in upper leaves, ending below apex in lower; cells in basal part narrowly rectangular, 70–115 μm long, 6–10 times as long as wide, cells above smaller, narrowly rectangular, bistratose, 4–5 × 20–40 μm in mid-leaf. Perichaetial leaves from sheathing basal part abruptly narrowed to long acumen. Setae yellowish, becoming brown with age; capsules inclined, ovoid, curved, strumose, sulcate when dry; lid with curved acuminate beak; spores 16–22 μm. Capsules common, summer to winter. n = 13∗ , 14, 15. On damp, acidic, sandy or gravelly soil, ditch banks, partially shaded peat especially in peat cuttings. Lowland. Generally distributed, occasional to frequent but rare in N. Scotland and Ireland. 84, H32. GB178 + 102∗ , IR15 + 3∗ . Circumpolar Boreal-montane. Europe, Faeroes, Iceland, Siberia, Japan, N. America, Greenland. May occur mixed with D. heteromalla but differs in the shorter curved strumose capsules, the leaves only finely denticulate towards the apex and with longer cells.

9 D. heteromalla (Hedw.) Schimp., Coroll. Bryol. Eur., 1856 (Fig. 56) Dioicous. Dull green or yellowish green tufts or patches, 1–3(−6) cm high. Leaves falcate-secund, rarely erect-patent when moist, scarcely altered when dry, from ovate or lanceolate basal part gradually tapering to long channelled acumen;

Fig. 56 1–4, Dicranella heteromalla: 1, leaves (×25); 2, basal cells (×420); 3, cells from upper part of leaf (×420); 4, capsule (×15).

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margins plane, denticulate above especially towards apex; costa strong, percurrent or excurrent, occupying c. 1/3 width of leaf base, occupying greater part of acumen; cells in basal part rhomboidal to narrowly rectangular, 30–50 μm long, 2–6 times as long as wide, smaller and narrower towards margins, cells above smaller, rectangular to narrowly rectangular and extending in narrow band towards apex, 4–6 × 10–14 μm wide in mid-leaf. Perichaetial leaves abruptly narrowed from sheathing basal part to long acumen. Setae yellowish, becoming brown with age; capsules inclined or horizontal, ellipsoid, gibbous, not strumose, sulcate when dry; lid with long curved acuminate beak; spores 12–17 μm. Capsules common, winter, spring. n = 7, 11, 11 + m, 13∗ , 14. 13 + 2–3m, 14. On banks in hedgerows, ditches, woods, among rocks, on tree boles and stumps, peaty banks on heaths and moorland, calcifuge but occurring in calcareous areas on leached soil and tree boles. 0–1100 m. Common and sometimes abundant or locally dominant. 112, H38, C. GB1940 + 79, IR255 + 7∗ , C3. Circumpolar Boreo-temperate. Europe north to northern Scandinavia, Faeroes, Iceland, Caucasus, Turkey, Lebanon and Himalayas northwards, Malaysia, Macaronesia, Kenya, N. America, Bolivia. Easily recognised by the silky falcate-secund leaves and yellow setae. Plants on sandstone may have narrower erect-spreading or subsecund leaves and have been referred to as var. sericea (Schimp.) Schimp. but such plants are merely an extreme form of a continuous series.

Subfamily 2 DICRANOIDEAE Plants usually large. Leaves straight or falcate, narrowly lanceolate, acuminate; basal cells often porose, alar cells usually differentiated from other basal cells, often coloured, upper cells smooth or papillose. Capsules ovoid to cylindrical, straight or curved, rarely strumose, smooth or striate; peristome teeth divided to about half way, pitted-striolate below, papillose above. 31 ARCTOA BRUCH & SCHIMP. IN BRUCH ET AL., BRYOL. EUR., 1846 Autoicous. Leaves from ovate or lanceolate basal part abruptly or gradually narrowed to long channelled acumen; costa longly excurrent; in section with or without stereids; basal cells elongate, walls not porose, a few alar cells differentiated, brownish, cells above shorter. Perigonia bud-like, immediately below perichaetia. Setae short, thick; capsules erect, slightly asymmetrical, furrowed when dry. Three north temperate and arctic species. Derivation: from the northern distribution of the genus.

1 A. fulvella (Dicks.) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1846 Dicranum fulvellum (Dicks.) Sm. (Fig. 57) Dense yellowish green to green tufts, brownish or blackish below, 0.5–3.0 cm high. Leaves slightly crisped or secund when dry, erect-flexuose to falcate-secund

31 Arctoa

195

Fig. 57 1–5, Arctoa fulvella: 1, leaves (×20); 2, alar cells (×320); 3, cells c. 1 /3 way up leaf (×320); 4, 5, mature and dry empty capsules (×15). 6–11, costa sections, all except 11 c. 1 /4 from base. 6, Arctoa fulvella; 7, Kiaeria falcata; 8, K. starkei; 9, K. blyttii; 10, K. glacialis; 11, K. glacialis, c. 3 /4 from base. Costa sections ×320.

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when moist, from ovate or lanceolate basal part narrowed to long faintly denticulate acumen composed almost entirely of longly excurrent costa; basal cells elongate, not porose, alar cells quadrate, brownish, distinct, cells above narrowly rectangular, in upper part irregularly quadrate at margins, narrowly rectangular by costa, 4–8 μm wide in mid-leaf. Setae short, 2–4 mm long, thick, yellowish; capsules erect, ovoid, slightly asymmetrical, contracted below mouth and widemouthed with spreading peristome teeth when dry and empty; lid with oblique beak; spores c. 20 μm. Capsules common, summer. n = 14. On basic or acidic rocks, in crevices on mountain tops and cliffs, often in areas of late snow-lie. 450–1340 m. Rare to occasional in N. Wales, Lake District and Scottish Highlands, S. Kerry, W. Donegal. 23, H2. GB45 + 28∗ , IR2. European Arctic-montane. Europe north to Svalbard, Faeroes, Iceland, Japan, N. America. When fertile it is readily recognised by the erect wide-mouthed capsules with spreading peristome teeth. When sterile it may be distinguished from Kiaeria species by the leaves more abruptly contracted above the basal part and with longly excurrent costa. Blindia acuta is a plant of damper habitats and has inflated orange alar cells.

32 KIAERIA I. HAGEN, KONGEL NORSKE VIDENSK. SELSK. SKR. (TRONDHEIM)., 1915 Autoicous. Leaves lanceolate, longly tapering to acuminate apex; costa in section usually without stereids; alar cells brownish, distinct or not; basal cells porose or not. Perigonia bud-like, immediately beneath or far from perichaetia. Capsules ovoid to subcylindrical, inclined, strumose. An arctic–alpine genus of 5 species. Derivation: named after the Norwegian bryologist F. C. Kiaer (1835–1893).

1 Alar cells grading into other basal cells, leaf acumen with low papillae 2 Alar cells ± differentiated from other basal cells, forming distinct group, leaf acumen not papillose 3 2 Plants usually yellowish green or green, leaves scarcely altered when dry, exothecial cells thick-walled, annulus persisting 1. K. falcata Plants dull or dark green, leaves crisped when dry, exothecial cells thin-walled, annulus fugacious 2. K. blyttii 3 Leaves falcate, basal cells not or only slightly porose, cells above not porose 3. K. starkei Leaves erect-spreading to secund, basal and sometimes cells above porose 4. K. glacialis 1 K. falcata (Hedw.) I. Hagen, Kongel Norske Vidensk. Selsk. Skr. (Trondheim), 1915 (Figs. 57, 58) Dicranum falcatum Hedw. Dense yellowish to green tufts or patches, 1–2(−5) cm high. Leaves falcate-secund, hardly altered when dry, from lanceolate base tapering to papillose channelled

32 Kiaeria

197

Fig. 58 1–4, Kiaeria falcata: 1, leaves; 2, mid-leaf cells; 3, capsule (×15); 4, exothecial cells (×320). 5–8, K. blyttii: 5, leaves; 6, mid-leaf cells; 7, capsule (15); 8, exothecial cells (×320). 9–12, K. starkei: 9, leaf; 10, mid-leaf cells; 11, capsule (×15); 12, exothecial cells (×320). 13–16, K. glacialis: 13, leaves; 14, basal cells; 15, mid-leaf cells; 16, capsule (×10). Leaves ×15, leaf cells ×420.

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acumen; margins entire or slightly denticulate above; costa excurrent, in section without stereids; cells not porose, basal rectangular to narrowly rectangular, alar cells quadrate, brownish, grading with other basal cells and not forming distinct group, upper cells quadrate to shortly rectangular or rhomboidal, in upper part of leaf with low papillae. Perigonia immediately below perichaetia. Setae to 10 mm long; capsules inclined, ovoid, curved, strumose, sometimes furrowed but not striate when dry and empty; exothecial cells mostly less than twice as long as wide, strongly incrassate; annulus of 2–4 rows of small persisting cells; spores 14– 15 μm. Capsules common, summer. n = 7, 14. On or among sheltered boulders or on stones or coarse detritus, especially in areas of late snow-lie. 950–1340 m. Frequent on the higher Scottish mountains, very rare elsewhere, Caernarfon, Lake District, Dumfries. 24. GB44 + 6∗ . European Arctic-montane. Montane and northern Europe north to Svalbard, Jan Mayen, N. America. When lacking capsules, K. falcata may be distinguished from K. blyttii by its colour and the leaves being hardly altered when dry. It differs from K. starkei in its smaller size, indistinct alar cells and papillose leaf acumen; it also forms more compact tufts and the leaves are more regularly falcate.

2 K blyttii (Bruch & Schimp.) Broth., Laubm. Fennoskand., 1923 Dicranum blyttii Bruch & Schimp.

(Figs. 57, 58)

Dull to dark green or blackish green tufts or patches, 1–3(−5) cm high. Leaves somewhat crisped when dry, patent-flexuose, hardly secund when moist, 2–4 mm long, from lanceolate basal part tapering to papillose channelled acumen; margins entire; costa excurrent, in section without stereids; basal cells quadrate to quadrate-rectangular, rarely porose, alar cells quadrate, brownish, grading into other basal cells and not forming a distinct group, upper cells quadrate-rectangular to quadrate, in upper part of leaf papillose with protruding cell walls. Perigonia distant from perichaetia or on separate branches. Setae to 15 mm long; capsules inclined, ovate-ellipsoid, curved, strumose, not striate when dry and empty; exothecial cells mostly more than twice as long as wide, thin-walled; annulus a single row of fugacious cells; spores 16–19 μm. Capsules frequent, summer. n = 7, 8, 13 + m, 14. Among boulders and on rocks in block scree and on detritus on mountain ridges. 100–1340 m. Rare in N. W. Wales, Lake District, N. W. Yorkshire, N. Northumberland, S. W. Scotland, frequent in the Scottish Highlands, W. Mayo, W. Donegal, Londonderry. 24, H3. GB94 + 8∗ , IR3. European Boreo-arctic Montane. Montane and northern Europe north to Svalbard, Himalayas, N. Asia, Azores, N. America. K. blyttii differs from the other three British species of Kiaeria in having the perigonia distant from the perichaetia or on separate branches, in its dark green colour and the leaves somewhat crisped when dry. The other species are typically although mot exclusively late snow-patch species, a habitat in which K. blyttii is not found. K. falcata and K. starkei usually have strongly falcate leaves, which is not a feature of K. blyttii.

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3 K. starkei (F. Weber & D. Mohr) I. Hagen, Kongel Norske Vidensk. Selsk. Skr. (Trondheim)., 1915 (Figs. 57, 58) Dicranum starkei F. Weber & D. Mohr Yellowish green to green tufts or patches, 2–6(−10) cm high. Leaves flexuose when dry, erect to falcate-secund when moist, 2.0–4.5 mm long, from lanceolate basal part tapering to channelled acumen; margins entire or denticulate towards apex; costa excurrent, in section without stereids; basal cells quadrate to quadraterectangular, sometimes slightly porose, alar cells brown, often forming a distinct group, upper cells quadrate to rectangular, neither papillose nor porose, Perigonia immediately below perichaetia. Setae to 16 mm long; capsules ellipsoid to subcylindrical, curved, ± strumose, striate when dry and empty; exothecial cells mostly twice as long as wide, thin-walled; annulus of one row of large fugacious cells; spores 14–16 μm. Capsules frequent, summer. n = 7, 13 + m, 14. On stony ground, among rocks and boulders and on slabs, especially in areas of late snow-lie. 560–1340 m. Frequent on the higher Scottish mountains, very rare elsewhere, N. W. Yorkshire, Westmorland. 18. GB48 + 4∗ . Circumpolar Arctic-montane. Montane and northern Europe north to Svalbard, Turkey, N. Asia, N. America, Greenland. Easily confused with K. falcata as sometimes the alar cells do not form a distinct group. The thin-walled exothecial cells and fugacious annulus are distinctive. The plants are usually larger than those of K. falcata and the leaf acumen is not papillose.

4 K. glacialis (Berggr.) I. Hagen, Kongel Norske Vidensk. Selsk. Skr. (Trondheim)., 1915 (Figs. 57, 58) Dicranum glaciale Berggr. Lax tufts, yellowish green to green above, brown below, to 12 cm high. Leaves flexuose, erect to secund when dry, erect-patent to secund when moist, 5–7 mm long, from ovate or ovate-lanceolate basal part tapering to entire or obscurely denticulate channelled acumen; costa ending ± in apex, without lamellae or teeth on abaxial side above, in section with a few stereids on abaxial side; cells porose at least in lower part of leaf and often throughout, basal cells narrowly rectangular, alar cells brownish, forming distinct group, upper cells rectangular to narrowly rectangular, not papillose, 6–13 μm wide in mid-leaf. Setae to 15 mm long; capsules inclined, subcylindrical, curved, strumose, furrowed when dry and empty; exothecial cells more than twice as long as wide, incrassate; spores c. 16 μm. Capsules frequent, autumn. On stony or rocky ground or among boulders in areas of late snow-lie and on high-altitude ridges. 900–1330 m. Rare, Perth, Angus, S. Aberdeen, Banff, Inverness, Argyll, Ross. 11. GB18 + 6∗ . Circumpolar Arcticmontane. Czechoslovakia and Fennoscandia north to Svalbard, N. Asia, N. America, Greenland. More likely to be mistaken for a Dicranum species, especially D. scoparium, than for another Kiaeria species. Montane forms of D. scoparium may have entire leaves lacking lamellae and

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teeth on the abaxial side of the costa. However, it has wider mid-leaf cells, two rows of stereids in costa section, dwarf males and non-strumose capsules with a persisting annulus.

33 DICRANUM HEDW., SP. MUSC. FROND., 1801 Dioicous. Female plants usually robust, male plants minute or of similar size to female plants. Leaves erect to falcate-secund, from ovate or lanceolate basal part gradually tapering to acuminate apex; margins usually plane, frequently dentate or denticulate above; costa ending below apex to excurrent, in section usually with one or two stereid bands; cells incrassate, porose or not, basal linear or narrowly rectangular, becoming narrowly rectangular to quadrate above, mamillose or not. Setae straight; capsules erect or inclined, straight or curved, not strumose, often ± striate; peristome teeth reddish, divided to about half way into 2–3 unequal segments, pitted-striolate below, papillose above; lid rostrate; calyptrae cucullate. About 150 mainly north temperate and arctic–alpine species but also occurring on tropical mountains; replaced in the Southern Hemisphere by Dicranoloma (Renauld) Renauld. Derivation: from the Greek for a two-pronged fork, referring to the peristome teeth. D. montanum, D. flagellare, D. tauricum and sometimes D. scottianum are placed by some authorities in the genus Orthodicranum (Bruch & Schimp) Loeske but the characters separating this from Dicranum are poorly defined and the genus is not recognised here.

1 Leaf cells porose throughout 2 Only basal cells with porose walls or cells non-porose throughout 6 2 Leaf margins recurved below, spinosely toothed above 1. D. polysetum Leaf margins plane below, usually dentate but not spinosely so above 3 3 Leaves falcate-secund, 9–15 mm long, setae yellowish green 5. D. majus Leaves erect to secund, to 10 mm long, setae reddish at least below 4 4 Upper part of leaves deeply channelled or ± tubular, margins entire or weakly toothed above 3. D. leioneuron Leaves not deeply channelled or tubular above, margins usually toothed above 5 5 Leaves transversely undulate above, costa 40–70 μm wide at widest part of leaf, with 2–4 low lamellae and not or scarcely toothed on abaxial side above 2. D. bonjeanii Leaves plane or undulate above, costa 75–120 μm wide at widest part of leaf, with 4 toothed lamellae on abaxial side above 4. D. scoparium 6 Leaves rugose or undulate when moist 7 Leaves not rugose or undulate 8 7 Leaves incurved and crisped when dry, cells mamillose on abaxial side towards apex 6. D. spurium Leaves ± erect when dry, cells not mamillose 7. D. bergeri 8 Leaves flexuose, curved or crisped when dry 9 Leaves straight, appressed when dry 13

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9 Costa percurrent or excurrent, supra-alar cells longer than alar cells 10 Costa ending below apex, alar cells and supra-alar cells of similar length 12 10 Capsules erect, leaves erect-flexuose when dry, basal cells 2–4 times as long as wide, margins usually entire 11. D. scottianum Capsules inclined, leaves crisped when dry, basal cells 3–8 times as long as wide, margins entire to dentate 11 11 Leaf margins usually denticulate, costa papillose or toothed and cells smooth to coarsely mamillose on abaxial side above, cells towards apex ± quadrate 8. D. fuscescens Leaf margins entire or weakly denticulate, costa usually smooth and cells smooth on abaxial side above, cells towards apex variable in shape 9. D. flexicaule 12 Cells in upper part of leaf mamillose, margins and abaxial side of costa in upper part of leaf dentate, flagelliform branches absent 13. D. montanum Cells smooth, costa smooth, margins denticulate only near apex, flagelliform shoots usually present 14. D. flagellare 13 Leaves not fragile, usually intact, stems densely tomentose, montane 10. D. elongatum Leaves fragile, usually with missing tips, stems not tomentose, lowland 12. D. tauricum

Subgenus 1 Dicranum Costa ending below apex, occupying up to c. 1/8 width of leaf base, with stereids in section; alar cells unistratose, delimited from other basal cells and not extending to costa, cell walls porose throughout or only basal cells porose or all cells nonporose. Capsules inclined, curved. Section 1 Dicranum Male plants usually minute. Costa with distinct or indistinct lamellae on adaxial side above; cells elongate, smooth, walls porose throughout. Capsules inclined, curved, annulus lacking; peristome teeth striolate in lower part, papillose above. 1 D. polysetum Sw., Monthly Rev., 1801 (Fig. 60) D. undulatum F. Weber & D. Mohr, D. rugosum (Dicks.) Hoffm. ex Brid. Yellowish green tufts or patches, to 15 cm high. Stems tomentose. Leaves spreading, occasionally subsecund, strongly transversely undulate; margins recurved below, plane and coarsely spinosely toothed above; costa ending below apex, with 2 strongly toothed lamellae on abaxial side above; alar cells brownish, distinct, other cells ± uniformly narrowly elliptical with porose walls throughout leaf. Setae 1–5 per perichaetium; capsules inclined, strongly curved; unknown in Britain. n = 12, 12 + m, 12 + 3m, 14. In conifer and birch woods, on heaths and raised bogs. Lowland. Widely distributed but rare, extending from S. Hampshire north to

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Elgin. 33. GB34 + 17∗ . Circumpolar Boreal-montane. Europe north to Fennoscandia, Caucasus, Turkey, Siberia, Japan, N. America. The leaves scarcely altered when dry, strongly undulate and margins recurved below and coarsely spinosely toothed above will readily distinguish D. polysetum from other Dicranum species. D. spurium has the leaves incurved and crisped when dry and in D. bergeri the leaves are acute to obtuse rather than acuminate and the margins are entire to denticulate.

2 D. bonjeanii De Not. in Lisa, Elenco Muschi, 1837 (Fig. 59) Usually bright green tufts or turfs, to 13 cm high, rarely more. Stems tomentose. Leaves erect-patent to subsecund, transversely undulate above, scarcely altered when dry, 4–9 mm long, lanceolate, tapering to acute to obtuse apex; margins plane below, erect, dentate above; costa ending below apex, narrow, 40–70 μm wide at widest part of leaf, with 2(−4) low, scarcely toothed lamellae on abaxial side above, in section with one row of large empty cells; cell walls porose throughout leaf, basal cells linear to narrowly rectangular, alar cells brownish, distinct, cells above linear-rectangular to elliptical-rectangular, smooth. Flagelliform propaguliferous shoots occasionally present. Sporophytes 1–2 per perichaetium; setae reddish below, yellowish above; capsules inclined, cylindrical, curved; spores 18–20 μm. Capsules very rare, autumn. On wet or marshy ground, wet moorland, in fens, damp woods, and well drained basic grassland, rarely on acidic soils or among Sphagnum. 0–430 m. Widespread, rare to occasional in central England, southern and northern Scotland and Ireland, frequent to common elsewhere. 108, H27, C. GB615 + 138∗ , IR52 + 11∗ , C1 + 1∗ . Circumpolar Boreo-temperate. Europe north to Svalbard, Faeroes, Iceland, Turkey, Azores, N. and C. Africa, N. America, Greenland. A variable species some forms of which may be difficult to separate from paludal plants of D. scoparium which may have strongly undulate leaves. The latter has a wider costa, which has toothed lamellae on the abaxial side above, and the upper leaf cells are shortly rectangular to irregularly quadrate. D. bonjeanii is usually found in more eutrophic habitats than the next two species.

3 D. leioneuron Kindb., Bull. Torrey Bot. Club, 1889 (Fig. 59) Yellowish green tufts, to 8 cm or more high; stems sparsely tomentose. Leaves erect-flexuose when moist, not undulate, to 5 mm long, erect, narrowly lanceolate, gradually tapering to deeply channelled or ± tubular acumen; margins entire or weakly denticulate above; costa ending below apex, with two poorly developed toothless lamellae on abaxial side above; cells incrassate, walls porose throughout leaf, basal cells linear or narrowly rectangular, alar cells brown, distinct, cells above gradually becoming shorter narrowly rectangular. Flagelliform branches with small ovate to lanceolate concave appressed leaves sometimes present. Capsules unknown in Britain. On Sphagnum tussocks on raised and blanket bogs

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Fig. 59 1–3, Dicranum bonjeanii: 1, leaf; 2, basal cells; 3, mid-leaf cells. 4–6, D. leioneuron: 4, leaf; 5, basal cells; 6, mid-leaf cells. 7–13, costa sections, 7, 9, 11, 12 c. 1 /4 from apex, 8, 10, 13 c. 3 /4 from base. 7, 8, D. bonjeanii; 9, D. leioneuron; 10, 11, D. scoparium; 12, 13, D. majus. Leaves ×10, cells and sections ×320.

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and in drier habitats under heather and in thin turf over boulders. 0–800 m. Very rare, Brecon, Cardigan, Montgomery, S. Northumberland, Cumberland, Mid Perth, Angus. 7. GB9 Circumpolar Boreal-montane. Norway, Sweden, Finland, Spain, W. Russia, Mongolia, Siberia, N. America. Most likely to be confused with and overlooked as D. scoparium as it occurs in a wider range of habitat types than was originally thought (see M. F. V. Corley, J. Bryol. 16, 485–6, 1991). It differs from that species and D. bonjeanii in the leaf margins being entire or only weakly denticulate and the upper part of the leaf being deeply channelled or almost tubular. D. bonjeanii has strongly undulate leaves. The flagelliform branches of D. leioneuron are a useful character when present but they may also occur on D. bonjeanii growing amongst Sphagnum. For the occurrence of this plant in Britain see T. Ahti et al., Bryologist 68, 197–201, 1965. This species is treated as vulnerable in the Red List of British Mosses.

4 D. scoparium Hedw., Sp. Musc. Frond., 1801 (Figs. 59, 60) Lax or dense, yellowish green to dark green tufts or patches, to c. 10 cm high; stems tomentose. Leaves crowded, erect to secund, flexuose when moist, hardly altered when dry, sometimes undulate above, 5–10 mm long, gradually tapering from ovate-lanceolate or lanceolate basal part to channelled acumen; margins plane, entire to serrate above; costa ending below apex, 75–120 μm wide at widest part of leaf, with 4 toothed lamellae on abaxial side above, in section with 1 row of large cells; cells incrassate, walls porose throughout leaf, basal cells narrowly rectangular, alar cells brown, distinct, cells becoming shorter above, 12–16 μm wide in mid-leaf, upper cells rectangular to irregularly quadrate, at margins rhomboidal, cells in lower half of leaf ± quadrate in section. Sporophytes usually 1 per perichaetium; setae yellowish above, reddish below; capsules suberect, cylindrical, curved, smooth, 3–4 mm long excluding longly rostrate lid; spores 12–22 μm. Capsules frequent in wetter parts of the British Isles and in humid habitats, rare elsewhere, summer to winter. n = 11, 12∗ , 12 + m∗ , 13, 13 + m, 14, 14 + 3m. In a wide range of exposed to sheltered habitats including acidic or leached soil in woodland, grassland, bogs, marshes, on heaths, moorland, sand-dunes, rocks, bark, walls, calcifuge. 0–1220 m. Frequent or common and sometimes locally abundant. 112, H40, C. GB1998+91∗ , IR164 + 7∗ , C2 + 1∗ . Circumpolar Wide-boreal. Europe north to Svalbard, Faeroes, Iceland, Turkey, Caucasus, N. Asia, Mongolia, Japan, Macaronesia, N. Africa, N. and C. America, Andes, Greenland, New Zealand. A very variable plant for which a number of varieties have been described but because of phenotypic plasticity these cannot be satisfactorily discriminated (see D. Briggs, New Phytol. 64, 366–86, 1965). Luxuriant plants with secund leaves may resemble D. majus but differ in the leaves having toothed lamellae on the abaxial side of the costa and, in section, with laminal cells ± quadrate and the costa with only one row of large cells. Small plants with entire leaves lacking toothed lamellae may be confused with the alpine species Kiaeria glacialeis (q.v.). In D. fuscescens, D. flexicaule and D. scottianum the leaf cells are narrower and non-porose at least above the basal part, and in the first two species the leaves are crisped when dry. For the differences from D. bonjeanii see under that species.

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Fig. 60 1–4, Dicranum scoparium: 1, leaves of (a) woodland plant, (b) marsh plant, (c) exposed dry ground plant; 2, basal cells; 3, mid-leaf cells; 4, capsule. 5–7, D. polysetum: 5, leaf; 6, basal cells; 7, upper cells. 8–11, D. majus: 8, leaf; 9, basal cells; 10, mid-leaf cells; 11, capsule. Leaves ×10. cells ×320, capsules ×7.5.

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5 D. majus Turner, Muscol. Hibern. Spic., 1804 (Figs. 59, 60) Lax light green to dark green tufts or patches, to 15 cm high; stems tomentose. Leaves not crowded, uniformly falcate-secund, flexuose when moist, hardly altered when dry, not undulate, 9–15 mm long, from lanceolate basal part narrowing to long channelled acumen; margins plane, serrate above; costa ending below apex, 90–120 μm wide at widest part of leaf, without lamellae but toothed on abaxial side above, in section with two rows of large cells; cells incrassate with porose walls throughout leaf, basal cells narrowly rectangular, alar cells brownish, distinct, cells above narrowly rectangular or rectangular, rhomboidal at margins, cells in lower half of leaf rectangular in section. Sporophytes 1–5 per perichaetium; setae yellowish green; capsules inclined to horizontal, shortly cylindrical, curved, to 3 mm long excluding longly rostrate lid; spores 14–26 μm. Capsules occasional to frequent in wetter parts of the British Isles and in humid habitats, rare elsewhere. n = 11, 12∗ , 12 + m∗ , 13. On rocks, soil and bark in woods, among boulders, on heaths and moorland, rock ledges and sheltered banks, calcifuge. 0–1080 m. Rare in lowland Britain except in the south, frequent or common and sometimes locally abundant elsewhere. 101, H33, C. GB1055 + 103∗ , IR115 + 19∗ , C4 + 1∗ . Circumpolar Boreo-temperate. Europe north to Svalbard, Faeroes, Iceland, Turkey, Caucasus, N. and C. Asia, China, Korea, Japan, N. America, Greenland. Section 2 Spuria Bruch & Schimp. in Bruch et al., Bryol. Eur., 1847 Male plants minute. Leaves transversely undulate; margins serrate; costa ending below apex or excurrent, abaxial side smooth or mamillose; cell walls in lower part of leaf porose, in upper part isodiametric, not porose. Peristome teeth rough. 6 D. spurium Hedw., Sp. Musc. Frond., 1801 (Fig. 61) Tumid green or yellowish green cushions, to 10 cm high; stems tomentose. Leaves incurved, crisped, rugose when dry, erect on new growth, otherwise spreading, rugose when moist, 5–7 mm long, from ovate or ovate-lanceolate basal part narrowed to acuminate often twisted apex; margins entire to serrate; costa ending below apex, mamillose but not toothed on abaxial side above; basal cells ± linear with porose walls, alar cells brownish, distinct, cells above rhomboidal, not porose, coarsely mamillose on abaxial side. Capsules suberect, curved; spores 14–24 μm. Capsules very rare, summer. n = 12. On wet and dry heaths and on banks in sparse Pinus sylvestris woodland. Lowland. Occasional in Hampshire, Sussex, Surrey and eastern central Scotland, very rare elsewhere and decreasing. 30. GB43 + 36∗ . European Boreal-montane. N., W. and C. Europe, Siberia, Sikkim, eastern N. America. This species is treated as vulnerable in the Red List of British Mosses.

7 D. bergeri Blandow in Sturm, Deutschl, Fl., 1805 D. affine Funck, D. undulatum Schrad. ex Brid.

(Fig. 61)

Large dull to yellowish green tomentose tufts, to 15 cm high. Leaves erect-patent, transversely undulate and rugose when moist, hardly altered when dry, 4–7 mm

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Fig. 61 1–3, Dicranum spurium: 1, leaf (×10); 2, basal cells; 3, mid-leaf cells. 4–6, D. bergeri: 4, leaf (×10): 5, basal cells; 6, mid-leaf cells. 7–9, D. elongatum: 7, leaves (×20); 8, basal cells; 9, mid-leaf cells. 10–14, D. fuscescens: 10, leaves (×10); 11, basal cells; 12, mid-leaf cells; 13, cells near leaf apex; 14, capsule (×7.5). 15–17, D. flexicaule: 15, leaves (×10); 16, basal cells; 17, cells near leaf apex. Cells ×320.

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long, from lingulate to ovate-lanceolate basal part tapering to acute to obtuse apex; margins plane, denticulate or occasionally entire above; costa not mamillose and not or only slightly toothed on abaxial side above; basal cells linear with porose walls, alar cells brownish, distinct, cells above quadrate-rectangular to elliptical or rhomboidal, neither porose nor mamillose. Capsules suberect, narrowly ellipsoid, curved; spores 20–24 μm. Capsules rare, summer. n = 11, 12, 13. Mainly on raised bogs, rare and decreasing. 0–350 m. Scattered localities from Cardigan and Shropshire north to Caithness, Offaly. 15, H1. GB16 + 11∗ , IR3. Circumpolar Boreo-arctic Montane. N., W. and C. Europe, Iceland, Caucasus, C. Asia, Japan, N. America. This species is treated as vulnerable in the Red List of British Mosses.

Section 3 Fuscescentiformia Kindb., Eur. N. Amer. Bryin., 1897 Male and female plants of similar size. Leaves falcate to falcate-secund, deeply channelled above with inflexed margins; costa ending below apex to excurrent, occupying up to 1/4 width of leaf at widest part of leaf; cells near base sometimes porose. Capsules inclined and curved or erect and straight; annulus of 1–3 rows large cells; peristome teeth striate below, papillose above. 8 D. fuscescens Turner, Muscol. Hibern. Spic., 1804 (Fig. 61) Dull green or yellowish green tufts or patches, to 12 cm high. Stems tomentose. Leaves ± crisped when dry, suberect to strongly falcate-secund, rarely ± erect and straight when moist, 4–8 mm long, from ovate-lanceolate or lanceolate basal part tapering to denticulate or occasionally entire long channelled acumen; costa ending below apex to excurrent, 100–200 μm wide at widest part of leaf, usually denticulate on abaxial side above; basal cells narrowly rectangular, 3–8 times as long as wide, walls porose or not, alar cells brownish, distinct, cells above not porose, in mid-leaf 8–12(−16) μm wide, cells in upper part of leaf of ± uniform shape, quadrate or shortly rectangular, smooth to strongly mamillose on abaxial side. Setae yellowish, becoming reddish with age; capsules inclined, subcylindrical, curved, striate; spores 18–24 μm. Capsules occasional, autumn. n = 8, 9∗ , 10∗ , 10 + m∗ , 12, 24. On soil, rocks, rock faces and bark in deciduous and coniferous woodland and ravines, on boulders, cliff faces and on Racomitrium heath. 0–1205 m. Very rare in lowland England, frequent or common elsewhere, occasional in Ireland. 83, H22. GB499 + 55∗ , IR45 + 6∗ . Circumpolar Boreo-arctic Montane. Europe north to Svalbard, Faeroes, Iceland, Turkey, N. and C. Asia, Japan, N. America, Greenland. A very variable species which may be confused with D. flexicaule (q.v.) or D. scottianum. D. fuscescens is easily distinguished from the latter by its inclined capsules and, when sterile, by the leaves usually crisped when dry. However, forms of D. fuscescens with ± straight leaves may present problems. Such plants can be recognised by one or more of the following characters: leaf margins denticulate above, upper cells mamillose on abaxial side, costa

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toothed and/or papillose on abaxial side above, basal cells 3–8 times as long as wide; none of these characters is present in D. scottianum but one or more of them, except length of basal cells, may be absent in plants of D. fuscescens.

9 D. flexicaule Brid., Bryol. Univ., 1826 (Fig. 61) D. congestum auct. non Brid., D. fuscescens var. congestum auct. non (Brid.) Kindb. Lax or dense dull green or yellowish green tufts, patches or turfs, to 10 cm high. Leaves flexuose to crisped when dry, subsecund to strongly falcate-secund when moist, lanceolate, tapering to long channelled entire or weakly denticulate acumen; costa ending in apex to excurrent, smooth or sparsely toothed on abaxial side above; basal cells narrowly rectangular, 3–8 times as long as wide, walls porose or not, alar cells brownish, distinct, cells above not porose, in mid-leaf 8–12(−16) μm wide, cells towards apex of variable shape, rectangular, rhomboidal and quadrate mixed together, not mamillose on abaxial side. Capsules inclined, subcylindrical, curved; unknown in the British Isles. On rocks, cliff ledges and soil, usually at high altitudes but descending to near sea level in W. Sutherland. 10–1340 m. Rare, N. W. Yorkshire, N. Northumberland and Mid Perth north to Caithness, Outer Hebrides. 11. Circumpolar Boreo-arctic Montane. Montane and northern Europe north to Svalbard, N. and E. Asia, N. America. Probably under-recorded, being mistaken for high-altitude D. fuscescens, which is indistinguishable in the field. D. flexicaule is a poorly defined species as some of the characters distinguishing it from D. fuscescens – ± entire acumen, non-mamillose upper cells, costa not toothed on abaxial side – may occur individually in the latter species. Experimental studies into the status of D. flexicaule are required.

Section 4 Elongata I. Hagen, Kongel Norske Vidensk. Selsk. Skr. (Trondheim), 1914 Leaves acute to obtuse, margins incurved above; upper cells quadrate to shortly rectangular, not porose or elongate and porose. Capsules curved or ± straight; annulus cells large; peristome teeth papillose and striate or smooth above or throughout. ¨ 10 D. elongatum Schleich. ex Schwagr., Sp. Musc. Frond. Suppl. 1, 1811 (Fig. 61) Densely matted, yellowish green tufts, to 6(−12) cm high; stems tomentose. Leaves ± straight, appressed when dry, erect-patent, sometimes secund when moist, lanceolate or narrowly lanceolate, tapering to short entire or denticulate acumen; costa wide, ending in or below apex; basal cells narrowly rectangular or rectangular, porose, alar cells brownish, distinct, cells above rhomboidal, not porose, 6–10(−12) μm wide in mid-leaf. Capsules suberect, ovoid, curved; not known in Britain. n = 13. On peaty soil or peat overlying rocks. To 1150 m. Very rare and seen recently only in S. Aberdeen, old records from N. Northumberland, Angus, Inverness, W. Ross, Caithness, Shetland. 8. GB1 + 5∗ . Circumpolar

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Arctic-montane. Montane and northern Europe north to Svalbard, Iceland, Caucasus, C. Asia, Japan, Colorado, Greenland. This is a critically endangered species in the Red List of British Mosses.

Section 5 Crassinervia Roth, Eur. Laubm., 1904 Costa broad, excurrent; cells in upper part of leaf rounded-quadrate, partially bistratose, in section with projections between cells. Capsules straight or slightly curved; annulus cells large; peristome teeth slightly striate or weakly papillose. Leaf tips fragile, caduceus. 11 D. scottianum Turner, Muscol. Hibern. Spic., 1904 Orthodicranium scottianum (Turner) Roth

(Fig. 62)

Dull green tufts or cushions, to 7.5 cm high. Leaves usually erect-flexuose when dry, erect-patent, sometimes slightly secund when moist, lanceolate to narrowly lanceolate, tapering to entire or rarely weakly denticulate channelled acumen; costa excurrent, smooth on abaxial side above, 17–30% width of lamina at widest part; basal cells rectangular, 2–4 times as long as wide, walls very rarely porose, alar cells brownish, distinct, cells above ± uniformly quadrate, not porose or mamillose, 8–11 μm wide in mid-leaf. Capsules erect, cylindrical, straight or slightly curved; spores 25–30 μm. Capsules occasional to frequent, summer. n = 8∗ , 12∗ . On usually ± vertical, exposed or sheltered rock faces, rarely on bark. 0–430 m. Occasional to frequent in the Weald, S. W. and N. England, W. Wales, W. Scotland, W. Ireland, very rare elsewhere, Jersey. 46, H21, C. GB176 + 38∗ , IR55 + 24∗ , C1 + 1∗ . Western Europe from Portugal north to Svalbard, Switzerland, Macaronesia, N. America.

Subgenus 2. Orthodicranum Bruch & Schimp. in Bruch et al., Bryol. Eur., 1851 Leaves longly acuminate from lanceolate basal part, costa ending below apex or excurrent, occupying 1/5 –1/3 width of leaf base, with or without stereids in section; alar cells unistratose, extending nearly to costa, basal cells elongate, walls ± porose, cells above quadrate to shortly rectangular, not porose. Capsules erect. 12 D. tauricum Sapjegin, Bot. Jahrb. Syst., 1911 D. strictum (Dicks.) Sm., Orthodicranum strictum (Dicks.) Broth.

(Fig. 62)

Light green tufts or patches, to 4 cm high. Leaves straight, appressed when dry, erect-patent when moist, lanceolate, tapering to narrow channelled acumen composed mainly of costa which is frequently broken off; margins entire or finely denticulate; costa longly excurrent, smooth or very finely denticulate on abaxial side above, without stereids in section; alar cells hyaline or brownish, extending almost to costa, ± unistratose, cells near base rectangular, walls not or slightly porose, cells above rectangular to quadrate, smooth, not porose, 9–12 μm wide in

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Fig. 62 1–4, Dicranum scottianum: 1, leaf (×10); 2, basal cells; 3, mid-leaf cells; 4, capsule. 5–8, D. montanum: 5, leaf (×20); 6, leaf apex (×125); 7, basal cells; 8, mid-leaf cells. 9–12, D. flagellare: 9, leaf (×20); 10, basal cells; 11, mid-leaf cells; 12, capsule. 13–15, D. tauricum: 13, leaves (×20); 14, basal cells; 15, mid-leaf cells. Cells ×320, capsules ×7.5.

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mid-leaf. Capsules erect, cylindrical, straight; spores 14–18 μm. Capsules very rare. n = 12∗ , 12 + 2m, 14. In woodland on logs, tree stumps, bark, rarely on rock. Lowland. Occasional to frequent and increasing in lowland England, rare elsewhere, from N. Somerset east to Kent and north to Elgin. 66. GB213 + 11∗ . European Temperate. Europe north to Fennoscandia, Iceland, Turkey, Algeria, Kerguelen Is., N. America. D. tauricum is tolerant of some degree of atmospheric pollution and has increased markedly since 1930. Broken-off leaf tips probably act as a means of vegetative propagation.

13 D. montanum Hedw., Sp. Musc. Frond., 1801 Orthodicranum montanum (Hedw.) Loeske

(Fig. 62)

Small, green or dark green tufts or cushions, to 3 cm high. Leaves strongly curled when dry, spreading, flexuose, sometimes subsecund when moist, lanceolate, tapering to long denticulate acumen; costa ending below apex, toothed on abaxial side above, in section with stereids; cell walls not porose, alar cells hyaline or brownish, ± extending to costa, cells near base rectangular, cells above shortly rectangular to quadrate, mamillose on abaxial side, 12–16 μm wide in mid-leaf. Small propaguliferous shoots sometimes produced at stem tips; deciduous leaves also common. Capsules erect, cylindrical, straight; not known in Britain. n = 7, 12, 13, 14. On trunks, branches and exposed roots, rarely on sandstone, in woods and on banks. Lowland. Frequent and increasing in S. E. England, rare elsewhere, extending north to Elgin. 63. GB165 + 18∗ . Circumpolar Boreo-temperate. Europe north to Fennoscandia, Turkey, Siberia, Kashmir, Himalayas, China, Azores, N. America, Peru. When dry very similar in appearance to Dicranoweisia cirrata but differing in the denticulate leaf margins and differentiated alar cells extending to the costa.

14 D. flagellare Hedw., Sp. Musc. Frond., 1801 Orthodicranum flagellare (Hedw.) Loeske

(Fig. 62)

Green or yellowish green tufts or patches, to 5 cm high. Leaves crisped when dry, erect-patent to subsecund when moist, tapering to ± tubular entire or weakly denticulate acumen; costa ending below apex, slightly toothed on abaxial side above, in section with stereids; alar cells brownish, unistratose, extending ± to costa, cells near base rectangular, walls not porose, cells above rhomboidal to irregularly quadrate, not mamillose or porose, c. 12 μm wide in mid-leaf. Small, erect, propaguliferous flagelliform branches usually present. Capsules erect, subcylindrical, straight. Capsules very rare, summer. n = 12. On decaying logs and tree stumps in woodland. 0–370 m. Occasional in S. E. England, very rare elsewhere, extending from Glamorgan and N. Lincolnshire north to Mid Perth. 20. GB31 + 12∗ . Circumpolar Boreo-temperate. Europe north to northern Fennoscandia, Caucasus, Asia, Madeira, N. America, Guatemala, Mexico. Readily distinguished from all other species of Dicranum by the flagelliform propagules.

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Subfamily 3 CAMPYLOPODIOIDEAE Leaves lanceolate, longly tapering; costa usually occupying more than half width of leaf near base, usually with dorsal and ventral stereid bands with a median row of guide cells; alar cells differentiated, forming auricles or not, cells above ovate to elongate. Setae usually strongly cygneous so that capsules are frequently buried in the perichaetial leaves; peristome teeth opening when moist. 34 DICRANODONTIUM BRUCH & SCHIMP. IN BRUCH ET AL., BRYOL. EUR., 1847 Dioicous. Leaves gradually or abruptly narrowed to long, channelled, entire or denticulate acumen composed mainly of costa; costa in section with one row of guide cells and an adaxial and abaxial band of stereids; alar cells ± inflated, sometimes extending to costa, hyaline or brownish, often not persisting; basal cells near costa rectangular, becoming narrower towards margins, cells above becoming narrower, porose or not. Setae straight or cygneous; peristome teeth vertically striate below, papillose or not above; calyptrae entire or fringed. A mainly Northern Hemisphere genus of 7 species. Derivation: meaning two-pronged tooth, referring to the peristome teeth. For a monograph of the genus see J.-P. Frahm, Acta Bot. Fenn. 34, 179–204, 1997.

1 Leaf margins toothed almost to base 2. D. asperulum Margins toothed in upper half of leaf only 2 2 Costa in lower part of leaf clearly defined, cells beside costa above auricles hyaline 1. D. uncinatum Costa not clearly defined, cells beside costa above auricles not hyaline 2. D. denudatum ¨ 1 D. uncinatum (Harv.) A. Jaeger, Ber. Thatigk. St. Gallischen Naturwiss. Ges., 1880 (Figs. 63, 64) Dicranum uncinatum (Dicks.) Sm. Silky tufts, golden yellow above, brownish below, to 12 cm high. Leaves falcatesecund, less commonly erect or secund when moist, hardly altered when dry, from ovate or oblong sheathing basal part with entire margins rapidly narrowed to long setaceous acumen with margins denticulate from c. half way up leaf; costa longly excurrent, well defined below, to c. 1/4 width of leaf base, excurrent, finely denticulate on abaxial side above; alar cells inflated, hyaline to brownish, not persisting, cells by costa above alar cells broadly rectangular, hyaline, other basal cells quadrate-rectangular, walls not porose, at margins ± linear, forming border extending to shoulder of basal part, cells above narrowly rectangular to linear, with single marginal row shorter. Setae arcuate or straight; capsules erect; calyptrae fringed. Capsules unknown in the British Isles. On acidic humus on montane slopes, cliff ledges and rock faces, in moist shaded situations. 0–750 m. Frequent

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Fig. 63 1–3, Dicranodontium uncinatum: 1, leaf (×10); 2, leaf apex; 3, basal cells. 4–6, D. asperulum: 4 leaf (×10); 5, leaf apex; 6, basal cells. 7–10, D. denudatum: 7, leaf (×10); 8, leaf apex; 9, basal cells; 10, capsule (×7). 11–13, Campylopus subporodictyon: 11, leaves (×7.5); 12, alar cells; 13, cells c. 1/4 from leaf base. Apices ×130, cells ×320.

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Fig. 64 Costa sections about 1 /4 from leaf base. 1. Campylopus subporodictyon; 2, Dicranodontium asperulum; 3, D. uncinatum; 4, D. denudatum. All ×420.

in N. W. Scotland, rare elsewhere, Lake District, Kirkcudbright, eastern Scottish Highlands, W. Galway, W. Mayo, old records from N. Kerry and Wicklow. 18, H4. GB50 + 11∗ , IR8 + 2∗ . Suboceanic Boreal-montane. Western and central Europe, Yugoslavia, Himalayas, Sri Lanka, Java, Philippines, Taiwan, Japan, Morocco. Whilst easily identified microscopically, this and D. asperulum may be difficult to separate in the field. D. uncinatum usually has falcate-secund leaves, whereas D. asperulum usually has the leaves ± straight to secund.

2 D. asperulum (Mitt.) Broth., Nat. Pflanzenfam., 1901 Dicranum asperulum Mitt.

(Figs. 63, 64)

Silky yellowish green tufts, to 7.5 cm high. Leaves flexuose when dry, erect-patent to secund, occasionally falcate-secund when moist, often deciduous, from ovate sheathing basal part abruptly narrowed to long spinosely denticulate setaceous subula; margins denticulate from shoulders of and sometimes almost from base of sheathing part; costa longly excurrent, well defined below, 1/4 –1/3 width of leaf near base, spinosely denticulate on abaxial side above; alar cells inflated, hyaline to brownish, cells beside costa above alar cells enlarged, other basal cells quadrate to quadrate-rectangular, walls not porose, linear at margins, cells above narrowly rectangular to linear, single marginal row shorter. Setae straight; capsules erect; calyptrae entire. Capsules not known in the British Isles. On acidic humus among rocks, on steep mountain slopes and rock ledges in damp sheltered situations. 330–850 m. Rare, Caernarfon, Roxburgh, Stirling and Perth north to Sutherland, Leitrim, Cavan, Fermanagh. 19, H3. GB27 + 3∗ , IR4 + 1∗ . Suboceanic Boreal-montane. Central and northern Europe, Carpathians, Sikkim, Taiwan, Japan, N. America.

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3 D. denudatum (Brid.) E. Britton in R. D. Williams, N. Amer. Fl., 1913 (Figs. 63, 64) Dicranodontium longirostre (F. Weber & D. Mohr) Bruch & Schimp. Silky yellowish green or green patches or lax or rarely dense tufts, to 5(−10) cm high; stems with reddish brown tomentum. Leaves soft, rarely rigid, often deciduous, erect to secund, flexuose when dry, spreading to secund when moist, from ovate-lanceolate sheathing basal part gradually tapering to smooth or slightly denticulate acumen; margins recurved, ± entire; costa longly excurrent, poorly defined in lower part of leaf, 1/3 –1/2 width of leaf base, smooth on abaxial side above; alar cells inflated, forming hyaline or brownish auricles, cells beside costa above alar cells narrowly rectangular, not hyaline, other basal cells rectangular, not porose, narrower at margins, cells above rectangular to rhomboidal. Setae straight or cygneous; capsules cylindrical, straight, smooth; calyptrae entire. Capsules very rare. n = 11, 11–12. On damp shaded rocks, decaying wood and peaty soil in woods and occasionally in open habitats. 0–950 m. Frequent or common in montane areas, very rare elsewhere, E. Cornwall, S. Devon, S. Hampshire, Sussex, Stafford, Cheshire, Waterford, Wexford, Wicklow, Dublin, frequent in western Ireland. 57, H17. GB239 + 27∗ , IR37 + 6∗ . European Boreal-montane. Europe north to Finland and Sweden, Iceland, Caucasus, Siberia, Himalayas, China, Taiwan, Korea, Japan, N. America, Mexico, Colombia, Hawaii. D. denudatum may be distinguished from other Dicranodontium species by its habitat and deciduous leaves. Var. alpinum (Schimp) I. Hagen is regarded as no more than a habitat variant.

35 CAMPYLOPUS BRID., MUSCOL. RECENT. SUPPL., 1819 M. F. V. Corley

Dioicous or sterile. Moderate-sized to very robust plants; stems with central strand. Leaves long with wide basal part, tapering to channelled or tubular acuminate upper part; margins ± incurved throughout. Costa wide, 1/3 or more leaf width near base, reaching apex or excurrent, sometimes forming a hyaline hair-point; in section with median layer of large transversely oval cells, an adaxial layer of clear cells of very variable size and an abaxial layer of small cells of which alternate cells usually project downwards to form low ribs which are rarely produced to form lamellae several cells high; between median and abaxial band is another layer of clear cells or an intermediate band of groups of stereid cells. Alar cells often differentiated to form auricles; basal cells rectangular, wider beside costa than at margins, gradually or abruptly passing into upper cells which are of very variable shape and size, vermicular or more often consisting of longitudinal rows of mainly trapezoid and shortly rectangular cells mixed with a few quadrate and triangular cells. Vegetative propagation frequently occurs by one or more of the following deciduous structures: whole leaf tips, shoot tips or specialised diminutive leaves.

35 Campylopus

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Perichaetial leaves have wider basal portion and narrower costa. Male plants as large as female, rarely reduced and gemmiform. Setae yellow to light brown, cygneous with capsules buried in the leaves before maturation but erect and flexuose when the capsules are ripe (except in C. subulatus where it is erect throughout); capsules inclined, ellipsoid, straight or slightly curved with mouth slightly oblique, striate; calyptrae cucullate, fringed at base but fringe often deciduous; lid conicalrostrate; annulus of 2–3 rows of cells, separating; peristome teeth 16, divided to a little over half way, orange-brown below with transverse bars and minute vertical striations, becoming hyaline and papillose above; spores finely verrucose. Derivation: meaning bent foot, referring to the arcuate setae. A very large genus of c. 750 species, primarily occurring in the tropics; in temperate regions most numerous in areas of high rainfall. The British Isles are richer in species, all of which are calcifuge, than any other part of Europe. Hybrid sporophytes (C. flexuosus × C. fragilis) have been found once; the spores were abortive.

Notes on the identification of Campylopus species In the following key and descriptions measurements are made as follows: costa width is measured just above the auricles or in an equivalent position if auricles are absent; costa sections are taken c. 1/4 way up leaf unless otherwise stated; the proportion of the thickness of the costa (in the middle) in section occupied by the adaxial cells is given as a percentage of the total costa thickness. Costa section characters are of great importance for the identification of Campylopus species. The key that follows uses other characters first but costa section characters are also given. Wherever there is any doubt sections should be made. 1 Costa c. 3/4 width of leaf near base, cells porose ± throughout leaf, basal cell deep brown, alar cells longer and narrower, costa in section with stereids forming broad band on adaxial side of costa, rare plant 13. C. subporodictyon Plants lacking above combination of characters 2 2 Tall, usually blackish plants with long hair-points on some leaves (often broken off others), cells usually vermicular, lower cells pigmented 9. C. atrovirens Plants lacking above combination of characters 3 3 Basal cells above auricles hyaline, sharply delimited from green cells along an oblique line from costa to margins (as in Tortella species), leaves often with hair-points 4 Basal cells pigmented or if hyaline not delimited as above, hair-points absent 6 4 Lower green cells ± vermicular, costa section with stereids on both sides (although few on adaxial side) 12. C. brevipilus

218

5

6 7

8

9

10

11

12

12 Dicranaceae Lower green cells not vermicular, costa section with stereids confined to abaxial side 5 Fertile plants usually with nodose shoots (sterile plants usually not nodose), abaxial side of costa smooth or with ribs one cell high, widespread plant 11. C. introflexus Nodose shoots never present, abaxial side of costa in upper part of leaf with lamellae 2–4 cells high (best seen in section from upper part of leaf), plant of western coasts 10. C. pilifer Auricles absent or very rarely weakly developed 7 Auricles conspicuous 10 Lower cells narrow, to 14 μm wide, plants often with deciduous shoot tips, costa section without stereids 8 Lower cells wider, to 20 μm or more wide, plants often with deciduous leaves, costa section with abaxial stereids 9 Slender non-tomentose loosely growing plants, leaves less than 4 mm long 1. C. subulatus Small to robust, densely tufted plants, either with tomentose stems or with leaves more than 4 mm long 2. C. schimperi Leaves widest at 1/8 –1/4 from base, tapering towards base, plants robust 4. C. fragilis Leaves widest at or almost at base, shoots slender 5. C. pyriformis Costa 2/3 or more of leaf width at base, costa section without stereids 3. C. gracilis 2 11 Costa less than /3 leaf width near base, costa in section with stereids Leaves gradually tapering to stout acumen, costa section without adaxial stereids and with adaxial cells smaller and more numerous than median cells 6. C. flexuosus Leaves distinctly contracted above basal part into slender acumen, costa section not as above 12 Stems without tomentum, costa section with adaxial cells occupying up to half costa thickness, leaves toothed above 7. C. setifolius Stems tomentose, costa section with adaxial cells occupying more than half costa thickness, leaves almost entire 8. C. shawii

Subgenus Pseudocampylopus Limpr., Laubm. Deutschl., 1886 Costa in section without stereids. 1 C. subulatus Schimp. in Rabenh., Bryoth. Eur., 1861 (Figs. 65, 68) Slender golden yellow or yellowish green loose turfs, low patches or scattered plants, 0.4–3.0(−5.0) cm high; tomentum lacking or rarely present at base in taller plants. Leaves 2–4 mm long, erect, straight when moist, more appressed when dry, parallel-sided at base for (1/10)1/5 –1/3 of length, tapering above at first strongly then

35 Campylopus

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Fig. 65 Campylopus: transverse sections of costa c. 1 /4 from leaf base. 1, C. subulatus: 2, C. schimperi: 3, C. gracilis: 4, C. fragilis: 5, C. setifolius: 6, C. pyriformis var. pyriformis, from typical plant; 7, C. pyriformis, from slender plant; 8, C. flexuosus, from typical plant; 9, C. flexuosus, from xeromorphic form; 10, C. shawii. All ×420.

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12 Dicranaceae

gradually to apex, acumen rather short; margins entire below, faintly denticulate near apex which ends in 1–2 larger teeth; lamina cells in 2–9 rows at mid-leaf. Costa shortly excurrent, 1/2 –2/3 leaf width, in section with adaxial cells larger than median, occupying 32–47% of costa thickness, stereid cells absent, abaxial side of costa rough with low ribs. Basal cells thin-walled, hyaline, linear to rectangular, with hyaline cells continuing up margins in a tapering band; alar cells slightly wider and more incrassate than basal cells but usually little differentiated, rarely forming ± distinct hyaline auricles; upper cells subquadrate, shortly rectangular and trapeziform, 4–9 μm wide. Vegetative propagation by deciduous shoot tips. Setae erect, straight when moist and when dry, 1 cm long; capsules erect, ellipsoid, symmetrical or slightly asymmetrical; very rare, found only once in Britain. In sheltered sandy or gravelly places on roadsides, banks, by streams, rarely on damp rocks. 0–850 m. Occasional in western Britain from Cornwall north to W. Ross and Orkney, very rare in S. E. England and eastern Scotland, very rare in Ireland, Jersey. 34, H8, C. GB67 + 16∗ , IR3 + 6∗ , C1. Suboceanic Temperate. From Spain east to Yugoslavia and north to Scandinavia, Faeroes, Iceland, Turkey, Bhutan, Yunnan, California, C. America. 2 C. schimperi Milde, Bot. Zeit., 1864 C. subulatus var. schimperi (Milde) Husn.

(Figs. 65, 66)

Densely matted green to yellowish green tufts, 2.5–8.0 cm high; matted with reddish tomentum in lower part or rarely almost without tomentum. Leaves 2.5– 7.5 mm long, erect, often lightly secund when moist, becoming more appressed when dry, basal part parallel-sided for up to 1/3 of leaf length then tapering gradually to apex, apex entire or minutely denticulate, ending in 1–3 teeth; upper part of leaf sometimes finely papillose on abaxial side; lamina cells in 1–3(–8) rows at mid-leaf. Costa shortly excurrent, 1/2 –2/3 width of leaf base; in section with adaxial cells much larger than median, occupying 46–55% of costa thickness; stereids absent; adaxial side of costa with low ribs which are sometimes obsolete. Basal cells hyaline or slightly chlorophyllous, thin-walled, linear or rectangular, often not clearly delimited from upper cells; alar cells fragile, slightly wider than basal cells, hyaline or brownish, sometimes forming distinct hyaline auricles, upper cells shortly rectangular or trapeziform, 3–10 μm wide. Vegetative propagation by fragile leaf tips and occasionally deciduous leaves or shoot tips. Capsules not known in the British Isles. In areas of late snow-lie, in corries and gullies, on mountain ridges and banks below cliffs. (60−)400–850 m. Very rare but occasionally locally abundant, from Stirling and Arran north to Shetland, Kerry, Wicklow, W. Donegal. 18, H4. GB24 + 19∗ , IR3 + 6∗ . Circumpolar Arctic-montane. Montane and northern Europe north to Svalbard, Faeroes, Iceland, Caucasus, China, Himalayas, Japan, Alaska, Greenland. This species varies considerably in size, plants from lower altitudes in W. Scotland and Ireland being taller and longer leaved, while those from C. and E. Scotland and high

35 Campylopus

221

Fig. 66 1–4, Campylopus fragilis: 1, leaf (×15); 2, alar cells; 3, cells from shoulder of leaf base; 4, capsule (×10). 5–7, C. gracilis: 5, leaf (×20); 6, alar cells; 7, cells 1 /4 from leaf base. 8–10, C. schimperi: 8, leaf (×25); 9, alar cells; 10, cells 1 /4 from leaf base. Cells ×320.

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altitudes in the west are more stunted with short leaves and more abundant tomentum. C. schimperi is very close on the one hand to C. subulatus and on the other to C. gracilis. Some authors have relegated it to varietal status under C. subulatus but it differs markedly in size, leaf length, distinctness of basal areolation, habit and habitat from that species and is not very likely to be confused with it, so it seems best to keep them apart. Confusion is more likely with C. gracilis, but this has the costa wider and excurrent for about half the leaf length besides having auricles constantly present and generally lacking tomentum. The leaf base of C. schimperi is longer and more sharply contracted into the acumen than in C. gracilis.

¨ 3 C. gracilis (Mitt.) A. Jaeger, Ber. Thatigk. St. Gallischen Naturwiss. Ges., 1872. (Figs. 65, 66) C. schwarzii Schimp. Gametangia unknown. Robust dense glossy yellow-green or golden tufts or turfs, 1–8 cm high; tomentum absent or very scanty. Leaves 2.5–8.0 mm long, erectpatent, straight or slightly secund, rarely strongly falcate when moist, becoming more erect and appressed when dry, tapering gradually from just above auricles to entire or faintly toothed apex, ending in 1–3 teeth; lamina cells in 0–2 rows in mid-leaf. Costa longly excurrent, excurrent part comprising about half total leaf length, very wide, 3 /5 –4 /5 leaf width; in section with adaxial cells large, occupying 40–53% of costa thickness; stereids absent; abaxial side of costa with low ribs. Basal cells hyaline or slightly chlorophyllous, thin-walled, linear or rectangular, not clearly differentiated from upper cells; alar cells forming conspicuous hyaline or mauve-red auricles, upper cells thick-walled, rectangular or trapeziform, 3–12 μm wide, linear at margins. Vegetative propagation by fragile leaf tips and shoot tips. Capsules unknown. In shallow bogs and flushes, on soil amongst rocks on steep slopes and on flushed rocks, slabs and dripping rocks. 0–900 m. Sometimes frequent on upland moorland and on mountains, occasional to frequent in N. W. Wales, the Lake District and W. Scotland north to W. Sutherland and the Outer Hebrides, Angus, occasional in Ireland especially in the west. 24, H13. GB99 + 16∗ , IR28 + 5∗ . Suboceanic Boreal-montane. Montane Europe north to Norway, Faeroes, Iceland, Himalayas, Taiwan, Japan, Korea, Kamchatka, British Columbia. Var. huntii (Stirt.) Dixon is a highly aberrant plant, possibly belonging to this species.

Subgenus Campylopus Costa in section with stereids on abaxial side only. 4 C. fragilis (Brid.) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1847 (Figs. 65, 66) Lax green turfs or dense tufts, 0.5–8.0 cm high, with abundant red-brown tomentum in large plants. Leaves 3–6 mm long, erect-patent, straight, rather rigid when

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moist, more erect and appressed, slightly flexuose when dry, often strongly imbricate at apex of shoots, base obcuneate, widest at 1/3 –3/4 from base, then rapidly contracted to a tapering acumen, finely toothed in upper part with a few coarser teeth at apex; lamina cells in 1–6 rows at mid-leaf. Costa 1/3 –2/3 leaf width, ending in apex; in section with adaxial cells larger than median, occupying 35–66% of costa thickness, about equal in number to median cells; back of costa with low ribs. Basal cells rectangular, hyaline, in dried material tending to remain full of air bubbles after moistening, alar cells not differentiated, upper cells irregular, mainly trapeziform and rectangular, 3–19 μm wide. Abundant minute deciduous leaves often present at shoot tips; normal leaves and occasionally leaf tips may also break off. Capsules straight or slightly curved; peristome teeth 300–470 μm long; spores 9–20 μm. Capsules occasional, spring. More base-tolerant than other species of the genus, most commonly on peat on moorland and peaty soil on rocks and in rock crevices in woodland and near the sea, on rotting tree boles and logs, in limestone grassland and on sand-dunes. 0–760 m. Frequent in the south-west, west and north-west of Britain but rare or absent from much of lowland England and eastern Scotland, frequent in western Ireland. 86, H26. GB564 + 71∗ , IR106 + 10∗ , C2. Suboceanic Temperate. Europe north to Scandinavia, Faeroes, Turkey, Himalayas, Japan, Canary Islands, British Columbia, Arkansas, C. and S. America. Often confused with C. pyriformis, which has similar areolation and also lacks auricles but differing markedly in leaf shape and habit. C. fragilis has the leaves widest at some distance from the base, tapering gradually towards the base and rapidly above the widest point to the acumen. The wide leaf bases are conspicuous and usually whitish in moist plants. The shoots are thick and pencil-like (if of any length) with the leaves very closely placed on them and spreading widely when moist. The thickness of the shoots causes them to be rather few in number on a given area of ground. C. pyriformis has the leaves widest at or very shortly above the base, soon contracted to the shorter acumen; the leaves may or may not be contracted at the extreme base; the short basal lamina sometimes appears whitish as in C. fragilis but is never so conspicuous; the shoots are slender with the leaves less densely placed and more erect, allowing the shoots to grow closer together. The whitish leaf bases and habit should distinguish C. fragilis from all other non-piliferous Campylopus species.

5 C. pyriformis (Schultz) Brid., Bryol. Univ., 1826 C. fragilis var. pyriformis (Schultz) Agst. Low bright or yellowish green mats, 0.2–2.5 cm high; tomentum reddish, present only on large forms. Leaves 2.5–7.5 mm long (perichaetial leaves to 9.5 mm) long, erect-patent when moist, ± straight, the lower more appressed, the upper somewhat flexuose when dry, basal part ovate to ovate-lanceolate, abruptly contracted to long slender acumen, widest at or very near the insertion; margins toothed in upper half of leaf or only towards apex; lamina cells in 1–3(–4) rows at middle of leaf. Costa reaching apex or shortly excurrent, 1/3 –3/5 leaf width; in section with adaxial cells as large as or larger than median, occupying 32–54% of costa

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12 Dicranaceae

thickness, the two rows of cells about equal in number; stereids present on abaxial side of median cells in well grown plants but these cells are often thin-walled; abaxial side of costa with low ribs. Basal cells rectangular, hyaline, sometimes remaining air-filled when moistened; alar cells variable, usually undifferentiated, hyaline or pale red, rarely forming distinct auricles; upper cells irregular, mostly trapeziform or rectangular, 3–23 μm wide. Vegetative propagation by means of deciduous leaves or less frequently by diminutive leaf tips or shoot tips. Male plants similar to female or sometimes gemmiform. Capsules straight or sometimes asymmetrical, mouth slightly oblique; peristome teeth 260–400 μm long; spores 8–17 μm. Capsules occasional in well developed plants, spring. n = 10∗ , 12. The commonest species of Campylopus in the south and east of England. Leaf apices 20–42 μm wide 200 μm from tip, costa usually more than 2/3 of leaf width, in section with adaxial cells 14–19 μm high var. pyriformis Leaf apices very slender, 11–32 μm wide 200 μm from the tip, costa usually less var. azoricus than 2/3 leaf width, in section with adaxial cells 9–14 μm high Var. pyriformis (Figs. 65, 67) Pale or yellowish green, rarely dark green turfs, usually more than 1.5 cm high; tomentum sparse or absent. Leaf tips (16−)20–42 μm wide c. 200 μm from apex, toothed in upper part with teeth rather close together. Costa 2/3 –3/4 leaf width; in section with adaxial cells 14–19 μm high. Alar cells colourless, undifferentiated. Vegetative propagation by deciduous leaves, sometimes of reduced size, rarely by shoot tips or fragile leaf tips. On light, acid soils especially in open woodland and on peat on heaths and moorland, also on rotting tree stumps and logs. 0–800 m. Common in suitable habitats throughout the British Isles. 112, H39, C. GB1121 + 91∗ , IR175 + 10∗ , C8. Suboceanic Temperate. Europe north to Scandinavia, Madeira, Azores, north-east N. America, S. America, Australia, New Zealand. Var. azoricus (Mitt.) M. F. V. Corley, J. Bryol., 1976 (Fig. 67) C. azoricus Mitt. Loose yellowish green tufts, 0.5–3.5 cm high; tomentum sparse to abundant. Leaves long and slender, leaf tips narrow in all leaves but markedly so in perichaetial leaves, toothing very variable, sometimes from mid-leaf but most often only in upper quarter of leaf, teeth rather distant, rarely entire. Costa more excurrent, 1/3 –2/3 of leaf width; in section with adaxial cells 9–14 μm high. Alar cells rarely differentiated from other cells of leaf base, frequently pale red or brown. Vegetative propagation by fragile leaf tips, occasionally also by deciduous leaves but these never of reduced size. In bogs, on decaying tussocks of Molinia and Cyperaceae on damp peat, peaty soil and wet rotten logs. 0–580 m. Rare but widely distributed from E. Cornwall to Kent and north to W. Sutherland and

35 Campylopus

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Fig. 67 Campylopus pyriformis. 1–7, var. pyriformis: 1, shoot with sporophyte (×10); 2, leaf; 3, leaf apex; 4, alar cells; 5, cells at leaf base shoulder; 6, capsule (×10); 7, peristome tooth (×250). 8–10, var. pyriformis, juvenile form: 8, leaf; 9, leaf apex; 10, alar cells. 11–13, var. azoricus: 11, leaf; 12, leaf apex; 13, alar cells. Leaves ×15, apices ×115, cells ×320.

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Caithness, Longford, old records from Wicklow, W. Mayo and W. Donegal. 43, H4. GB40 + 18∗ , IR1 + 2∗ . Suboceanic Temperate. France, Germany, Denmark, Azores. C. pyriformis is a distinct species rarely confused in its typical form with related species. The numerous deciduous leaves scattered on the tops of the plants are characteristic but not always present. Some shoots of some plants superficially resemble Dicranodontium denudatum but the stems are not bare of leaves below as in the latter. Dicranella heteromalla has all the leaf cells rectangular and strongly chlorophyllous and the leaves are usually secund. In some plants of C. pyriformis there are no stereid cells in the costa section, the relevant cells being thin-walled; such plants could be mistaken for C. subulatus but this has the leaf cells smaller and narrower, the upper part of the leaf almost entire and the whole plant of a golden yellow colour and often taller than C. pyriformis. For the differences from C. fragilis and C. flexuosus see notes under those species. Most of the confusion that has arisen in the past between these two species and C. pyriformis has been due to var. azoricus not having been recognised as a distinct taxon. This variety does not resemble C. fragilis any more than does the type, except that the leaf bases are more conspicuous and whitish, especially in the perichaetial leaves. Confusion with C. flexuosus is due to the existence of forms of this variety with coloured alar cells and the absence of deciduous leaves. Otherwise, the variety differs from C. flexuosus in the same ways as does the type. Var. azoricus intergrades with var. pyriformis and not all plants can be assigned with certainty to one variety or other. The ´ M. F. V. Corley has been shown to be plant referred to as C. pyriformis var. fallaciosus (Ther.) a juvenile form of var. pyriformis. Rhizoidal gemmae have been reported from this species in Belgian and non-European material (see T. Arts & J.-P. Frahm, Bryologist 93, 290–4, 1990). On the basis of its world distribution, which is similar to that of C. introflexus i.e. western European and Southern Hemisphere, it has been suggested that C. pyriformis may have been introduced into Europe in historical times (see M. F. V. Corley & J.-P. Frahm, J. Bryol. 12, 187–90, 1982).

6 C. flexuosus (Hedw.) Brid., Muscol. Recent. Suppl., 1819 C. paradoxus Wilson

(Figs. 65, 68)

Forming dark green tufts, sometimes with shoots very uneven in length, plants 0.5–9.0 cm high; tomentum present but very variable in abundance, reddish, occasionally zoned in different colours. Leaves 2–7 mm long, erect-patent, straight or falcate-secund when moist, more appressed below, flexuose above when dry, parallel-sided or slightly tapering in basal 1/8 –1/4 , then gradually tapering to apex; lamina cells in (3−)4–19 rows at mid-leaf. Costa reaching apex but not excurrent, 1/ –3 / leaf width; in section with adaxial cells more numerous than median cells 5 2 (1.3:1 to 1.9:1) and smaller than them (16–36% of costa thickness); leaves of large plants occasionally have a few of the adaxial cells divided transversely giving the impression of stereid cells on adaxial side of costa; abaxial side of costa with or without low ribs. Basal cells rectangular, usually thick-walled; alar cells differentiated to form hyaline or reddish brown auricles, upper cells irregular, mainly

35 Campylopus

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Fig. 68 1–4, Campylopus flexuosus: 1, leaf (×15); 2, alar cells; 3, cells 1 /3 from leaf base; 4, capsule (×10). 5–7, C. subulatus: 5, leaf (×25); 6, alar cells; 7, cells 1 /4 from leaf base. 8–10, C. setifolius: 8, leaf (×15); 9, alar cells; 10, cells 1 /3 way up leaf. Cells ×320.

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trapeziform and shortly rectangular, 3–19 μm wide. Vegetative propagation by deciduous leaves or shoot tips, rarely by leaf tips. Capsules curved and asymmetrical with mouth ± oblique; peristome teeth 290–560 μm long; spores 10–17(−24) μm. Capsules occasional, spring. n = 10∗ , 11∗ , 12∗ . In exposed or sheltered situations on bare peat on heaths and moorland, humus in woodland, on rotten wood, less frequently on rocks on moorland and shaded vertical rock faces. 0–800 m. 111, H37, C. GB1279 + 105∗ , IR240 + 12∗ , C1 + 2∗ . Suboceanic Temperate. Europe north to Scandinavia, Faeroes, Iceland, Asia, Macaronesia, Africa, N., C. and S. America, Australia, New Zealand. Differs from all other British species of the subgenus Campylopus in the costa section, in which the adaxial cells are smaller and more numerous than the other cells of the median layer. Confusion can only arise with abnormal plants. Some robust forms have stereid-like cells on the adaxial side of the costa, which might lead to their being taken for a muticous form of C. brevipilus which, however, has quite different areolation. Stunted forms of C. flexuosus have poorly developed auricles and the adaxial cells of the costa section about as large as the median cells. Such plants might be mistaken for C. pyriformis but differ markedly in leaf shape, having gradually tapering leaves with many rows of cells at mid-leaf, whereas C. pyriformis has rapidly contracted leaves with slender acumens and only 1–3(−4) rows of lamina cells at mid-leaf.

7 C. setifolius Wilson, Bryol. Brit., 1855 (Figs. 65, 68) Deep loose dark green or olive-green tufts, often tinged dark brown, (1−)3– 13(−25) cm high; tomentum absent or a few pale rhizoids present. Leaves 3.0– 8.5 mm long, when moist straight, never falcate, erect-patent, often very laxly placed on stem, more flexuose when dry; parallel-sided or slightly narrowed towards base, gradually tapering to long acumen from 1 /12 –1/8 from base, upper quarter of base (rarely less) with numerous spinose teeth, apex crowned with 1–4 large teeth; lamina cells in 2–9 rows at mid-leaf. Costa not excurrent, 2/5 –3/5 width of leaf; in section with adaxial cells about equal in number and of similar size to median cells, occupying 30–52% of costa thickness; costa smooth or with low toothed ribs near apex. Basal cells rectangular, usually thick-walled with few to many cells with porose walls, rarely hyaline, becoming thick-walled above; alar cells forming large orange-red auricles, upper cells thick-walled, irregular, mostly trapeziform or rectangular, occasionally shortly vermicular, 4–23 μm wide. Vegetative propagation by broken-off leaf tips or whole leaves, very rarely by shoot tips. Male plants much rarer than female. Capsules unknown. In very humid situations, on wet rock ledges and in block scree under tall heather on steep slopes, in spray zones of waterfalls and elsewhere where water drips from above, and in shallow bogs. 0–800 m. Rare but very locally frequent, N. W. Wales, the Lake District, Kirkcudbright and the far west of Scotland from Arran north to W. Sutherland and the Outer Hebrides, the far west of Ireland. 13, H12. GB62 + 6∗ , IR42 + 6∗ . Hyperoceanic Temperate. N. Spain.

35 Campylopus 8 C. shawii Wilson in Hunt, Mem. Lit. Soc. Manchester, 1868 ¨ C. setifolius var. shawii (Wilson) Monk.

229 (Figs. 65, 69)

Extensive yellowish green turfs, 3–11 cm high; tomentum reddish brown, abundant, conspicuous, rarely absent. Leaves 5.0–11.5 mm long, widely spreading to almost erect, straight or falcate when moist, becoming slightly appressed and flexuose when dry; parallel-sided at base for 1/8 –1/5 of leaf length or slightly narrowed towards base, gradually tapering above to long slender acumen, finely toothed at extreme apex only, rarely entire or toothed in the upper 1/8 of leaf, ending in 1–2(−3) small teeth; lamina cells in 1–4(−6) rows at mid-leaf. Costa not or scarcely excurrent, 2 /5 –2/3 of leaf width; in section with adaxial cells equal in number to median cells but not much larger, occupying 48–70% of costa thickness; abaxial side of costa smooth or slightly roughened with very low ribs. Basal cells rectangular, thick- or thin-walled, if thin-walled then these cells giving way to thick-walled cells further up leaf, lowest thick-walled cells with or without porose walls; alar cells forming conspicuous hyaline or reddish brown auricles, upper cells rather thin-walled, walls sometimes porose, mostly trapeziform or rectangular, 3–22 μm wide. Vegetative propagation by fragile leaf tips or occasionally whole leaves. In wet turf, flush bogs and flushes, in peat cuttings and wet rock ledges, in high rainfall districts. 0–440 m. Very local but abundant in some areas, W. Inverness, Mull, Skye, W. Ross, W. Sutherland and the Outer Hebrides, Kerry, W. Cork, W. Mayo. 6, H4. GB51 + 12∗ , IR8 + 3∗ . Hyperoceanic Southern-temperate. Azores, S. America. A striking plant more resembling one of the larger Dicranum species than a Campylopus but yellower in colour than is usual in the former genus and with wider costa. C. gracilis is somewhat similar but its leaves are shorter and have wider costa. The costa section of C. shawii with its very large adaxial cells will distinguish it at once from all other species with auriculate leaves.

9 C. atrovirens De Not., Syll. Musc., 1838 Plants 1–13(−20) cm; scarcely tomentose. Leaves 3.5–9.0 mm long, the terminal pieces of stem sometimes becoming detached and when this occurs these leaves may be very long, to 18 mm. Leaves erect-patent to erect, straight or rarely falcate when moist, more appressed, slightly flexuose or straight when dry, basal part lanceolate, tapering above to long entire acumen; lamina cells in 5–16 rows at mid-leaf. Costa excurrent in a spinose-dentate hair-point of very variable length, often lacking in some leaves and rarely in all leaves; costa 2 /5 –3 /5 leaf width; in section with adaxial cells slightly larger than median cells and about equal to them in number, 24–40% of costa thickness, abaxial side of costa with ribs one cell high. Basal cells shortly rectangular or quadrate, very incrassate, ± porose, rarely thinwalled; alar cells forming distinct hyaline or red-brown auricles, upper cells from very shortly above the base becoming trapeziform, linear or vermicular, rarely without some vermicular cells, incrassate throughout, walls usually porose in lower part of leaf only, 4–19 μm wide. Vegetative propagation by deciduous shoot

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Fig. 69 1–3, Campylopus shawii: 1, leaf; 2, alar cells; 3, cells near shoulder of leaf base. 4–6, C. atrovirens var. atrovirens: 4, leaf; 5, alar cells; 6, cells 1 /3 from leaf base. 7, C. atrovirens var. gracilis: leaf. 8, C. atrovirens var. falcatus: leaf. Leaves ×15, cells ×320.

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tips, and leaf tips which often break off at the base of the hair-point, occasionally whole leaves are deciduous. Capsules unknown in the British Isles. 1 Leaves strongly falcate, not flexuose when dry var. falcatus Leaves straight or if slightly falcate then flexuose when dry 2 2 Slender yellowish green plants with narrow leaves, basal cells thin-walled, upper cells not vermicular var. gracilis Plants without above combination of characters var. atrovirens

Var. atrovirens (Figs. 69, 71) Tall tufts or deep turfs, brownish black or greenish at shoot tips, yellowish brown or blackish within, whole plants commonly having a deep brown appearance. Leaves straight, erect or if falcate then becoming flexuose when dry. Basal cells walls very incrassate, porose, upper cells mostly vermicular or linear, rarely rectangular or trapeziform. n = 11∗ . In bogs and on wet rocks on moors and mountains. 0–940 m. Frequent in western Britain from Cornwall north to Shetland, common in the west of Ireland, occasional on mountains elsewhere. 60, H30. GB512 + 43∗ , IR121 + 13∗ . Hyperoceanic Temperate. Montane Europe north to Scandinavia, N. Caucasus, Pacific coast of N. America, N. Carolina. Var. falcatus Braithw., Brit. Moss Fl., 1882 (Fig. 69) Similar to var. atrovirens but leaves strongly falcate-secund with different shoots facing in different directions, unaltered when dry. Sporophytes unknown. In bogs and on wet rocks. Rare in areas of high rainfall near the west coast, Westmorland north to Sutherland and the Outer Hebrides, Shetland, S. Kerry, W. Cork, W. Galway, Sligo, W. Donegal, Antrim. 9, H6. GB17 + 7∗ , IR3 + 2∗ . Hyperoceanic Temperate. Norway. Var. gracilis Dixon, J. Bot., 1902 (Fig. 69) Plants more slender than the type, yellowish green, brown below, never blackish. Leaves sometimes slightly flexuose when dry, very slender, narrower than in the type. Basal cells thin-walled, walls scarcely porose, upper cells rectangular or trapeziform, not vermicular. In rocky or stony places. Very rare from Merioneth north to Angus and Skye but seen recently only in Dumfries, Angus, W. Inverness and the Outer Hebrides with an old record from W. Cork. 11, H1. Hyperoceanic Temperate. Endemic. C. setifolius and C. brevipilus are similarly coloured. The first has the leaf margins strongly toothed, whilst they are entire in C. atrovirens, teeth being confined to the hair-point. C. brevipilus has the basal cells thin-walled and hyaline, these cells ascending higher at the margins than next to the costa, but the costa section is the surest way to distinguish them.

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10 C. pilifer Brid., Muscol. Recent. Suppl., 1819 (Figs. 70, 71) C. polytrichoides De Not., C. introflexus var. polytrichoides (De Not.) Giacom. Loose green tufts or patches, brown or blackish below with individual stems densely leaved and rather thick as in C. fragilis, 0.5–5.0(−9.0) cm high; tomentum reddish, variable in abundance, Leaves 3.0–5.5 mm long, straight, erect-patent when moist, more tightly appressed when dry, with straight hair-points; parallelsided at base for 1/4 –1/3 of leaf length with a short evenly tapering entire acumen; lamina cells in 5–16 rows at mid-leaf. Costa excurrent in a short straight spinosetoothed hyaline hair-point; costa 1/2 –3/4 leaf width; in section with adaxial cells large, occupying 30–50% of costa thickness, approximately equal to median cells in number; numerous stereid cells in each group with rather thinner walls than is usual for such cells; abaxial rib cells large in lower part of leaf, smaller and thicker-walled in upper part and forming lamellae 2–3(−4) cells high. Basal cells rectangular, thin-walled, hyaline or chlorophyllous, extending higher at margins than at costa, usually sharply demarcated from upper cells along a straight oblique line (as in Tortella spp.); alar cells thin-walled, hyaline or pale reddish, forming auricles of very variable size; upper cells thicker-walled, rectangular or trapeziform, rather short, 4–15 μm wide. Vegetative propagation by deciduous leaves and shoot tips. Setae c. 4 mm long; capsules small, 0.76–0.87 mm long; spores c. 17 μm. Capsules very rare, found only once, in Ireland. On acid rocks or stony ground, usually near the sea, in warm, exposed situations. Lowland. Very rare on southwest and west coasts, Cornwall, S. Devon, Merioneth, Caernarfon, Jura, Skye, Lewis, Kerry, W. Cork, W. Galway, W. Mayo, Jersey, Guernsey. 8, H5, C. GB19 + 1∗ , IR17 + 1∗ , C9. Oceanic Southern-temperate. Coastal Europe north to Belgium and east to Italy, Turkey, Macaronesia, Africa, India to Java, southern N. America, C. America, Venezuela, Galapagos Islands. Similar in appearance to some forms of C. brevipilus but differs in habitat, in the costa section with no adaxial stereids and in the areolation which is of short trapeziform cells. Muticous forms are known from the Channel Islands and the Azores. Some plants are blackish below and might be mistaken for C. atrovirens, but that plant differs in the areolation, having the basal cells incrassate and the upper cells generally vermicular; it is also normally taller with longer leaves.

11 C. introflexus (Hedw.) Brid., Muscol. Recent. Suppl., 1819 (Figs. 70, 71) Olive-green or rarely green patches or loose tufts, often hoary when dry, 0.5– 5.0 cm high; fertile plants with swollen perichaetial or perigonial nodes and slender internodes; tomentum reddish brown, often rather scanty. Leaves 2.5–6.5 mm long, straight, erect-patent when moist, more tightly appressed when dry with hair-points strongly reflexed, particularly on nodal leaves, but sometimes straight if very short, leaves widest 1/8 –1/3 from base or parallel-sided for a similar length with upper part of leaf tapering, acuminate, entire; lamina cells in 3–13 rows at mid-leaf. Costa excurrent in strongly toothed hyaline hair-point, 1/4 –1/2 length of

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Fig. 70 1–4, Campylopus pilifer: 1, dry shoot tip (×5); 2, leaf; 3, alar cells; 4, cells c. 1 /3 from leaf base. 5–8, C. introflexus: 5, dry shoot tip (×7); 6, leaf; 7, cells c. 1 /3 from leaf base; 8, capsule (×15). Leaves ×20, cells ×320.

lamina but sometimes very short or lacking in some leaves, especially in the internodes, costa very variable in width, 1/3 –3/4 leaf width; in section with adaxial cells occupying 23–50% of costa thickness, approximately equal to the median cells in number or slightly more numerous; stereid cells few in each group and

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with large lumens; upper part of costa with ribs one cell high. Basal cells rectangular, becoming short and trapeziform above, thin-walled, hyaline, rarely slightly chlorophyllous, extending higher at margins than by costa, demarcated from upper cells along a curved or irregular line; alar cells thin-walled, hyaline to dark red-brown, forming auricles of variable size or auricles absent when the leaf base may be decurrent; upper cells very irregular, shortly rectangular, trapeziform or triangular, strongly incrassate, 8–15 μm wide. Vegetative propagation by deciduous leaves. Setae 7–12 mm long, shoots sometimes apparently polysetous (one seta from each of several perichaetia at one node); capsules ovoid-cylindrical, 1.0–1.4 mm long, deeply furrowed and shrunken when dry; peristome teeth 280– 420 μm long; spores 10–14 μm long. Capsules rare in drier areas, frequent and sometimes locally abundant in wetter parts of the British Isles, spring. n = 12∗ . Most commonly on bare peat and sandy or gritty soil in bogs, peat cuttings, by forestry tracks, on burnt moorland, rotten wood or tree boles, rarely on rocks and tiles. 0–400 m. Frequent except in the Midlands and parts of eastern Britain, common and often very abundant in Ireland. 110, H39, C. GB979 + 1∗ , IR223 + 2∗ , C2. Introduced (Suboceanic Temperate). Europe from Spain to southern Scandinavia and east to Czechoslovakia, Poland and Switzerland, Faeroes, New Guinea S. Africa, Southern N. America, C. and S. America, Galapagos Islands, New Zealand, Kerguelen Island, Falkland Islands. Introduced, first found in Sussex in 1941 and in Co. Dublin in 1942, since when it has spread very rapidly. Hardly likely to be confused with any other species except C. pilifer, from which it differs in the stems commonly having slender internodes and swollen nodes whereas in C. pilifer the stems are of uniform thickness. Some hair-points are usually strongly reflexed when dry, often to an angle of 90◦ or more; in C. pilifer they are straight or slightly reflexed. The two species also differ in colour and in habitat but the most useful distinction is in the costa section, taken in the upper part of the leaf, where C. pilifer has lamellae 2–3 cells high, whereas C. introflexus has low ribs one cell high. The setae and capsules are much larger in C. introflexus and capsules are so rare in C. pilifer that fruiting plants are almost certain to be C. introflexus. A form of C. introflexus occurs on acid gravelly soil such as tracks through heathland and forestry plantations with leaves lacking hair-points or with short straight hair-points and as the plants are sterile the stems are not nodose. Although they have the leaf morphology and areolation of C. introflexus they may be mistaken for C. flexuosus, especially as they may have deciduous shoot tips, or for C. pilifer. For the occurrence of this plant in the British Isles see P. W. Richards, Trans. Br. Bryol. Soc. 4, 404–17, 1963, and P. W. Richards & A. J. E. Smith, J. Bryol, 8, 293–8, 1975.

Subgenus Palinocraspis Limpr., Laubm. Deutschl., 1886 Costa section with stereids on adaxial and abaxial sides. 12 C. brevipilus Bruch & Schimp. in Bruch et al, Bryol. Eur., 1847 (Fig. 71) Yellowish green, olive or blackish brown, close turfs or loose patches, 0.5– 5.0 cm high; tomentum fairly plentiful but inconspicuous, pale brown. Leaves

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Fig. 71 1–3, Campylopus brevipilus: 1, leaf (×20); 2, alar cells (×330); 3, cells 1/2 from leaf base (×320). 4–11, leaf costa sections: 4, C. atrovirens var. atrovirens, 1 /4 from leaf base; 5, C. brevipilus, 1 /4 from leaf base. 6–8, C. pilifer: 6, near leaf tip; 7, 1/2 from leaf base; 8, near leaf base. 9–11, C. introflexus: 9, near leaf tip; 10, 1/2 from leaf base; 11, near leaf base. Sections ×420.

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2.5–6.0 mm long, straight, erect, rarely falcate when moist, more tightly appressed when dry but with the leaf tips free and straight or slightly reflexed hair-points, basal part of leaves oblong, elliptical or lanceolate, gradually tapering to entire acuminate apex, widest at 1/3 –1/2 from base, very variable in width relative to length; margins often narrowly recurved at about mid-leaf, especially in perichaetial leaves; lamina cells in 6–25 rows at mid-leaf. Costa excurrent, sometimes entire, but usually ± toothed, often forming a hyaline hair-point of variable length but never very long; 1/4 –1/2 leaf width, down to 1 /7 of leaf width in some perichaetial leaves; in section occasionally biconvex, adaxial layer of cells smaller than median, with a band of stereid cells between adaxial and median cells, often reduced to a few cells only; abaxial layer with more numerous stereids, arranged in groups, alternating with abaxial cells; abaxial side of costa smooth or slightly rough. Basal cells thin-walled, hyaline, rectangular, extending further up margins than near costa; alar cells forming small rather fragile auricles, hyaline or brownish, often not clearly differentiated from basal cells; upper cells from shortly above base becoming trapeziform, linear or shortly vermicular, 4–12 μm wide, walls usually strongly incrassate and often porose. Vegetative propagation by fragile shoot tips and occasionally whole leaves. Perichaetial leaves from wider base more suddenly contracted with hair-points longer than in vegetative leaves. Peristome teeth 350– 440 μm long; spores 11–13 μm. Capsules very rare. On heaths and moors, raised, valley and blanket bogs, acid fixed sand-dunes. Lowland. Always local, very common in some areas but unaccountably absent or very rare in other apparently suitable districts, occasional in the far south of England, west Wales, and the west of Scotland, extending north to Shetland, rare or very rare elsewhere, occasional to frequent in W. Ireland. 63, H24, C. GB219 + 64∗ , IR55 + 3∗ , C2. Oceanic Temperate. Europe east to Italy and Switzerland, north to Norway, Azores, Algeria. Perhaps the most variable species of the genus, showing great diversity in almost every character, particularly leaf width relative to length, presence or absence of hair-points, length of hair-points, and cell length and hence cell shape. The hair-points may vary not only from plant to plant but also up the stem; whole plants may lack hair-points altogether; such muticous forms are much more frequent than equivalent plants in other species and in some districts may form whole populations. The areolation in the best developed forms closely resembles that of C. atrovirens with its incrassate porose vermicular cells, but the basal cells of C. brevipilus are thin-walled and hyaline. The narrow costa, areolation and especially the costa section should distinguish C. brevipilus at all times.

13 C. subporodictyon (Broth.) B. H. Allen & R. Ireland, Linbergia, 2002 (Figs. 63, 64) Dicranodontium subporodictyon Broth., Dicranum subporodictyon (Broth.) Gao et al. Glossy yellowish green tufts, reddish below, c. 5 cm high. Leaves appressed, straight or with slightly flexuose points when dry, erect-patent when moist, with scattered

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dark brown rhizoids on abaxial side near base, from lanceolate basal part tapering to long channelled setaceous acumen consisting mainly of costa; margins inflexed, denticulate near apex; costa c. 3/4 width of leaf near base, ending in apex, not denticulate on abaxial side, also present on abaxial side; basal cells rectangular, incrassate, deep brown, walls porose, alar cells longer, narrower, not inflated, cells above elongate-rhomboidal, sinuose, porose, becoming narrower in upper part of leaf, marginal cells below very narrow, mid-leaf cells 10–12 μm wide. Sporophytes unknown. On flushed acidic rocks and slabs. 36–180 m. Very rare but sometimes locally abundant. W. Inverness, Skye, W. Ross. 2. GB5. Hyperoceanic Temperate. Sikkim, Yunnan, N. W. Canada. Very distinct in the broad costa, reddish brown basal cells and the scattered rhizoids near the leaf bases. The plant is possibly a Cretaceous relict. Originally placed in Dicranodontium and later transferred to Dicranum, it does not fit comfortably in either genus and has recently been transferred to Campylopus (see B. H. Allen & R. Ireland, Lindbergia 27, 77–8, 2003). For an account of D. subporodictyon in Scotland see E. C. Wallace & M. F. V. Corley, J. Bryol. 8, 85–9, 1974.

36 PARALEUCOBRYUM (LIMPR.) LOESKE, HEDWIGIA, 1908 Dioicous. Leaves lanceolate, acuminate; costa very wide, in section with 2–5 rows of hyaline cells with a middle layer of green cells, stereids lacking; alar cells inflated, hyaline or brownish. Capsules erect, cylindrical. A mainly Northern Hemisphere genus of 7 species. Derivation: meaning resembling Leucobryum.

1 P. longifolium (Ehrh. ex Hedw.) Loeske, Hedwigia, 1908 Dicranum longifolium Hedw.

(Fig. 72)

Silky tufts, pale green when moist, whitish when dry, to 4(−6) cm high. Leaves flexuose when dry, secund or falcate-secund when moist, from lanceolate basal part gradually tapering to channelled or ± tubular acumen composed entirely of costa; margins denticulate above, spinosely so near apex; costa 1/3 –1/2 width of leaf base, denticulate on abaxial side above, spinosely so near apex, longitudinally ridged on abaxial side above, in section with 3 rows of hyaline cells and a layer of chlorophyllous cells; basal cells rectangular, narrower towards margins, alar cells inflated, hyaline or brownish, lamina consisting of only 2–3 rows of shortly rectangular cells extending a short distance up leaf. Capsules erect, cylindrical, straight or curved; unknown in Scotland. n = 12, 14. On acidic or basic boulders in scree or by small lakes. 730–1000 m. Very rare, seen recently in Mid Perth, Banff and E. Inverness, old records from Dumfries, Angus and S. Aberdeen. 6. GB3 + 4∗ . Circumpolar Boreal-montane. Montane and northern Europe north to Fennoscandia, Faeroes, Iceland, Turkey, Caucasus, Siberia, Madeira, N. America, Greenland. This species is treated as vulnerable in the Red List of British Mosses.

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Fig. 72 1–2, Paraleucobryum longifolium: 1, leaf; 2, leaf section (×320). 3–5, Leucobryum glaucum: 3, leaf; 4, section of basal part of leaf (×175); 5, capsule. 6–8, L. juniperoideum: 6, leaves; 7, section of basal part of leaf (×175); 8, capsule. Leaves ×20, capsules ×10.

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13 Leucobryaceae Male plants minute, female plants large, whitish. Leaves consisting largely of costa, composed of 2 or more layers of large hyaline cells with large circular pores on inner walls and a central layer of chlorophyllous cells. Capsules erect or inclined, straight or curved, without stomata; peristome dicranoid. Four genera.

37 LEUCOBRYUM HAMPE, LINNAEA, 1839 Plants robust, forming compact cushions. Leaves composed mainly of costa, with a few rows of narrow hyaline cells towards the base representing the lamina; costa in section of 2 to several rows of hyaline cells with large irregular pores in the inner walls, with a central layer of small chlorophyllous cells. Sporophytes relatively small. A mainly tropical, taxonomically difficult genus of c. 180 species. Derivation: meaning white moss.

Basal part of leaves usually longer than narrowly triangular upper part, capsules markedly strumose, curved 1. L. glaucum Basal part of leaves shorter than ± parallel-sided upper part, capsules slightly strumose, slightly curved 2. L. juniperoideum 1 L. glaucum (Hedw.) Ångstr. in Fries., Summa Veg. Scand., 1846 (Fig. 72) Male plants minute, epiphytic on female plants. Female plants pale glaucous green when moist, whitish when dry, forming dense ± hemispherical cushions to 20(−50) cm high. Leaves imbricate when dry, erect-patent or sometimes subsecund in large plants when moist, mostly 6–9 mm long, composed mainly of costa, basal part ovate to lanceolate, 1.2–2.1 mm wide, usually longer than the narrowly triangular ± tubular upper part; margins entire; costa in section in middle of basal part 4–6 cells thick, adaxial cells 24–48 × 44–120 (−140) μm; basal cells, lamina of a few rows of elongate hyaline cells extending from base to near apex. Setae straight, 10–18 mm long; capsules curved, asymmetrical, markedly strumose, striate, sulcate when dry, 1.5–2.1 mm long; spores 16–20 μm. Capsules rare, autumn, winter. n = 11∗ , 14. On well or poorly drained soil and on rocks in woodland, on heaths, moorland, in bogs, calcifuge. 0–1030 m. Very rare in central and eastern England, frequent or common and sometimes locally abundant elsewhere. 107, H38, C. GB924 + 102∗ , IR174 + 14∗ , C1 + 4∗ . European Temperate. Europe north to northern Scandinavia, Turkey, Caucasus, Hong Kong, Japan, Macaronesia, eastern N. America, Colombia. In favourable situations colonies of L. glaucum grow to considerable size, as much as 2 m in diameter and 55 cm high, possibly by the coalescence of neighbouring plants. It has been estimated that such colonies may be about 70 years old (see J. W. Bates, J. Bryol. 15, 785–91,

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1989). Although sporophytes are rare, propagation by leaf and shoot fragments is very likely in both species in the British Isles. L. glaucum forms cushions of a more compact and neater appearance than those of L. juniperoideum, which often have the leaves slightly crisped when dry, and when the two are growing together the differences are obvious, as also when capsules are present. When sterile, L. glaucum may be identified by the leaves with the basal portion being longer than the upper part, which is narrowly triangular; in L. juniperoideum the basal part is shorter and abruptly narrowed into the upper part, which at least below has almost parallel sides.

¨ Hal., Linnaea, 1845 2 L. juniperoideum (Brid.) Mull. (Fig. 72) Male plants minute, epiphytic on female. Female plants forming ± hemispherical cushions, pale glaucous green when moist, whitish when dry, to 15 cm or more high. Leaves often slightly crisped when dry, often subsecund or secund when moist, mostly 5–7 mm long, basal portion ovate-lanceolate, 1.0–1.6 mm wide, usually shorter than the ± parallel-sided upper part; margins entire; costa in middle of basal part 2 cells thick, adaxial cells (15−)22–35(−44) × 33–110 μm, lamina of a few rows of elongate hyaline cells extending from base to near apex. Setae 8–12(−15) mm long; capsules slightly curved and inclined, weakly strumose, 1.0–1.6 mm long; spores 18–20 μm. Capsules rare, winter, spring. On well drained acidic soil, on rocks and tree boles in deciduous and rarely coniferous woodland, rarely on heaths, calcifuge. 0–400 m. Occasional in southern England and in Wales, very rare elsewhere in western Britain, extending north to Inverness, Kerry, W. Cork, Waterford, Carlow, W. Galway. 44, H6. GB76 + 3∗ , IR4. European Temperate. Western and central Europe, Turkey, Caucasus, China, Taiwan, Japan, ´ Macaronesia, N. America, Mauritius, Reunion, Madagascar. This is the plant referred to as L. albidum (Brid. ex P. Beauv.) Lindb. and L. minus (Hampe) Sull. by Dixon & Jameson (1924) and Braithwaite (1887), respectively. For the occurrence of L. juniperoideum in Britain and a detailed account of the two British species see A. C. Crundwell, J. Bryol. 7, 1–5, 1972.

14 Fissidentaceae Apical cell of stems bilateral. Leaves alternate, distichous in one plane. Each leaf consists of 3 parts: a conduplicate part, the sheathing lamina (or vaginant lamina), the apical lamina (or superior lamina) extending beyond the sheathing lamina and the dorsal lamina (or inferior lamina) forming the whole of the dorsal part of the lamina. Costa single; cells in upper half of leaf usually ± hexagonal, unistratose or bistratose in patches, 1–3-stratose border of narrow elongate cells present or not. Perichaetial leaves similar to stem leaves but sometimes longer and narrower. Sporophytes terminal or on short lateral branches; setae long or short; capsules erect or inclined, symmetrical or not; peristome dicranoid, of 16 deeply bifid teeth,

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rarely rudimentary; calyptrae mitriform or cucullate, entire at base. A taxonomically difficult but very natural family containing 5 genera and c. 1100 species most of which belong to Fissidens. It is thought that the sheathing lamina is derived from the true leaf lamina and that the apical and dorsal laminae are lamellar outgrowths. On the basis of peristome structure this family has affinities with the Dicranaceae but has greater specialisation of the gametophyte. It is because of this greater specialisation that I place the Fissidentaceae after other families of the Dicranales rather than before, as is done by most other authors.

38 FISSIDENS HEDW., SP. MUSC. FROND., 1801 Stems with central strand. Sheathing laminae c. 1/2 total length of leaf. Setae long; capsules longly exserted, with stomata. About 800 species, world-wide. For information on species 1–6 (the Fissidens viridulus complex) see M. F. V. Corley, J. Bryol. 11, 191–208, 1980 and on species 1–11 see M. A. Bruggeman-Nannenga, Proc. K. Ned. Akad. Wet. Ser. C 85, 59–104, 1982 and 88, 183–207, 1985. The latter author points out some useful distinguishing characters such as gametangia length and peristome tooth width. I have followed M. A. Bruggeman-Nannenga’s infrageneric treatment of the genus (Proc. K. Ned. Akad. Wet. Ser. C 81, 387–402, 1978). Derivation: meaning split tooth, referring to the peristome teeth.

1 Leaves with border of narrow elongate cells at least on sheathing laminae of perichaetial leaves; margins entire or obscurely denticulate above 2 Stem and perichaetial leaves unbordered; margins crenulate-serrulate or dentate above 15 2 Leaves gradually tapering to apex from below middle, cells c. twice as long as wide 15. F. curvatus Leaves ± abruptly narrowed to apex, cells ± isodiametric 3 3 Border present only on sheathing laminae of perichaetial leaves, minute aquatic plants 1.5–2.5 mm long 1. F. exiguus Border usually present on all laminae at least of perichaetial leaves, aquatic or terrestrial plants, if aquatic then 7–25 mm long 4 4 Capsules inclined or horizontal, leaf cells 6–10 μm wide, not protuberant 6. F. incurvus Capsules erect or inclined or if cernuous or horizontal then cells 4–8 μm wide and protuberant 5 5 Border confluent with costa at apex of stem leaves 6 Border not confluent with costa at apex of stem leaves 10 6 Antheridia in gemmiform axillary shoots, fertile plants 5–25 mm long 7 Antheridia on dwarf branches at base of female shoots, rarely in minute axillary buds, or plants dioicous or synoicous, fertile plants mostly 1.5–6.0 mm long 11

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7 Older parts of stems matted with deep red or occasionally brown rhizoids 8. F. curnovii Rhizoids ± sparse, brown or reddish brown 8 8 Leaf borders thin, 1(−3)-stratose, usually colourless, spores 10–14 μm, terricolous plants 7. F. bryoides Border 3 or more stratose, colourless or yellowish, spores 14–20 μm, plants aquatic or of habitats subject to submergence 9 9 Perichaetial leaves ± similar to upper stem leaves, leaf border yellowish, cells 8–10 μm wide, capsules ± erect 9. F. rivularis Perichaetial leaves markedly narrower than upper stem leaves, leaf border colourless, cells mostly 10–14 μm wide, capsules inclined 10. F. monguillonii 10 Sterile and fertile plants 5–20 mm long, spores 18–28 μm, aquatic plants 11 Fertile plants to 6(−7) mm long, sterile plants sometimes longer, spores 6–20 μm, plants terrestrial or aquatic 12 11 Leaf cells mostly 10–18 μm wide, archegonia 420–600 μm long, peristome teeth 51–86 μm wide at base 11. F. crassipes Leaf cells mostly 6–10 μm wide, archegonia 300–460(−560) μm long, peristome teeth mostly 43–66 μm wide 12. F. rufulus 12 Leaf cells 4–8 μm wide, usually protuberant in upper part of leaves 3. F. limbatus Cells mostly 8–15 μm wide, not or hardly protuberant in upper part of leaves 13 13 Perichaetial bracts 7–9 times as long as wide, costa percurrent to excurrent 5. F. gracilifolius Perichaetial bracts 4–6 times as long as wide, costa ending in or below apex 14 14 Perichaetial bracts ± similar to stem leaves but larger, sides of leaves at leaf apices usually concave (see Fig. 73, 12), plants terricolous 2. F. viridulus Perichaetial bracts longer and narrower than stem leaves, sides of leaves at apex often flat or convex (see Fig. 73, 6), plants saxicolous 4. F. pusillus 15 Plants to 5 mm long, costa ending below apex or percurrent 16 Plants larger, 1–10(−30) cm long, costa ending below apex to excurrent 17 16 Stems with 2–4 pairs of leaves, costa straight, cells 8–12 μm wide 13. F. exilis Stems with up to 18 pairs of leaves, costa with distinct bend half way up leaf, cells 12–20 μm wide 14. F. celticus 17 Leaves irregularly dentate towards apex, 3–4 rows marginal cells forming pale band especially in older leaves 18 Margins crenulate or regularly serrate above, marginal cells not differentiated 20 18 Leaf cells not mamillose, sporophytes borne on dwarf lateral or basal branches, setae red, common plants 19

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Leaf cells conically mamillose (best seen in side view of folded leaf), sporophytes terminal, setae yellowish, very rare plant 20. F. serrulatus 19 Cells in upper part of leaves 6–12 μm wide, partially bistratose, spores 10–16 μm 18. F. dubius Cells 12–20 μm wide, unistratose, spores 18–24 μm 19. F. adianthoides 20 Costa excurrent, cells 6–10 μm wide, shoots to 5 cm long, setae red 17. F. taxifolius Costa ending in or below apex, cells 8–22 μm wide, shoots 2–10 cm long, setae purple or yellow 21 21 Shoots to 10 cm long, leaves lingulate, cells 12–22 μm wide, setae purple 16. F. osmundoides Shoots to 20(−30) cm long, leaves narrowly lingulate or narrowly lanceolate, cells 8–14 μm wide 21. F. polyphyllus Section 1 Fissidens Plants small to large. At least sheathing lamina of leaves with border of elongate cells with pointed ends and margins entire or obscurely toothed above or all laminae unbordered and margins entire, crenulate or serrate at least above; cells smooth or rarely mamillose. Setae terminal; capsules usually with stomata. 1 F. exiguus Sull., Musc. Allegh., 1846 (Fig. 74) Dioicous. Scattered plants or small patches. Fertile plants 1.5–2.5 mm long with 2–4 pairs of leaves. Stem leaves ovate to lanceolate, acute; margins entire, unbordered; costa ending below apex; cells 8–12 μm wide in middle of apical lamina. Perichaetial leaves longer and narrower than stem leaves, to 5 times as long as wide, bordered only on sheathing lamina; costa ending below apex. Sporophytes terminal; setae red; capsules erect or slightly inclined; spores 10– 16 μm. Capsules common, spring. On shaded wet or submerged acidic rocks in streams and rivers. 0–205 m. Rare in S. E. England, very rare elsewhere, S. Devon, S. Somerset, Warwick, Brecon, Cumberland, N. Tipperary. 8, H1. GB12, IR1. European Temperate. Rare in Europe with definite records from Denmark, France and Germany, Azores, N. America. A reasonably good species, although almost impossible to separate from small forms of F. viridulus with poorly developed leaf border except by habitat, F. viridulus never occurs on wet or submerged stones or rock. Aquatic forms of F. pusillus are much larger with a well developed border on the stem leaves.

2 F. viridulus (Sw.) Wahlenb., Fl. Lapp., 1812 (Fig. 73) F. bryoides ssp. viridulus (Sw.) Kindb., F. viridulus var. bambergeri (Schimp.) Waldh. Dioicous, autoicous or synoicous. Dark green patches; fertile plants 2.5–6.0 mm long with 2–5(−8) pairs of leaves, sterile stems sometimes longer with more leaves. Stem leaves lingulate to narrowly lanceolate, 3–5 times as long as wide, often

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Fig. 73 1–5, Fissidens pusillus: 1, plant from limestone boulder in stream; 2, plant from shaded calcareous rock; 3, stem leaf (a, sheathing lamina; b, apical lamina; c, dorsal lamina); 4, perichaetial bract; 5, leaf tip; 6, leaf apices (×150). 7–8, F. gracilifolius: 7, plant; 8, perichaetial bract. 9–10, F. limbatus: 9, plant; 10, leaf tip. 11–12, F. viridulus: 11, plant; 12, leaf apices. (×150) Plants ×10, leaves ×40, cells ×420.

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acuminate or cuspidate with margins concave at apex (see Fig. 73, 12), but some leaves sometimes acute; margins entire or obscurely denticulate towards apex; border colourless, unistratose, always present on sheathing lamina and usually also present on apical and dorsal laminae, sometimes extending almost to leaf apex but not fusing with costa, not reaching base of dorsal lamina; costa ending below apex; cells irregular in shape and size, (6–)8–15 μm wide in middle of apical lamina, not protuberant. Perichaetial bracts of similar shape to but larger than stem leaves; costa ending below apex to excurrent. When autoicous, antheridia borne on short basal branches or rarely in minute axillary buds. Sporophyte terminal; setae red; capsules erect or slightly inclined, ellipsoid; spores 8–15 μm. Capsules common, winter, spring. n = 5, 10. On basic to slightly acidic soil on banks, stream sides, in woodland, amongst rocks and on thin soil overlying rock. 0–700 m. Common in England, Wales and S. Scotland but becoming rare further north, extending to W. Ross, occasional in Ireland. 75, H16. GB873 + 98∗ , IR86 + 7∗ , C7. Circumpolar Widetemperate. Europe to about 68◦ N, Asia, Macaronesia, Africa, N. and C. America, Australia. Confused in the past with F. pusillus and F. limbatus. F. pusillus differs in its perichaetial leaves longer and narrower than the stem leaves, the stem leaves with apex acute to obtuse, and always occurring on rock and sometimes being aquatic. Recent authorities stress the difference in apex shape of the leaves between the two species but I have seen numerous gatherings of F. pusillus with apices similar to those of F. viridulus. F. limbatus differs in the smaller, frequently protuberant cells and the perichaetial leaves longer and narrower than the stem leaves. F. bryoides differs in the bud-like axillary male branches which are almost invariably present. The plant referred to as F. viridulus var. bambergeri intergrades with F. viridulus and cannot be separated from it.

3 F. limbatus Sull., Expl. Railroad Mississippi Pacific, Descr. Moss. Liverw., 1856 (Fig. 73) F. herzogii Ruthe ex Herzog, F. minutulus Sull. non auct. angl. Synoicous, autoicous or dioicous. Small patches; plants 2–7 mm long with up to 15 pairs of leaves. Leaves lingulate to narrowly lanceolate, acute, acuminate or cuspidate; border colourless, unistratose, in upper leaves ending below apex to reaching apex and fusing with costa, border of dorsal lamina rarely reaching leaf base; costa ending in or below apex; cells irregular in shape and size, (3–)4– 8(–10) μm wide in middle of apical lamina, often protuberant. Perichaetial leaves longer and narrower than stem leaves, border ending below apex to reaching apex and fusing with costa; costa ending in or below apex. When autoicous antheridia borne on short basal branches or rarely in small axillary buds. Sporophytes terminal; setae red; capsules erect and symmetrical, ellipsoid; spores 8–18 μm. Capsules common, autumn to spring. n = 5. On basic to slightly acid soil in woods and on ditch and stream banks and on limestone or sandstone in sheltered but not wet sites. Lowland. Rare but widely distributed from Cornwall east to Sussex and north

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to Argyll and the Hebrides, rare in Ireland, Jersey. 38, H6, C. GB45 + 13∗ , IR6, C1. Mediterranean-Atlantic. S., W. and C. Europe, Turkey, Israel, Iran, Azores, Canary Islands. Plants of the F. viridulus complex occurring on soil or acidic rock with perichaetial leaves longer and narrower than the stem leaves are usually F. limbatus. There has been much confusion about the identity of F. minutulus Sull., which was thought for a time to be synonymous with F. pusillus. It has been shown that the name F. minutulus is an earlier name for F. limbatus; because of the confusion that would be caused by replacing the name F. limbatus with F. minutulus the name F. minutulus has been rejected in favour of the later name, F. limbatus.

4 F. pusillus (Wilson) Milde, Br. Siles., 1869 F. minutulus auct. non Sull., F. viridulus var. lylei Wilson

(Fig. 73)

Dioicous or autoicous. Plants dark green, gregarious or forming patches; fertile plants 1.5–6.0 mm long with up to 10 pairs of leaves. Leaves lingulate to narrowly elliptical, usually acute to obtuse with margins at apex straight or convex (see Fig. 73, 6); border colourless, yellow or reddish, 1–3-stratose, usually ending below apex, border of dorsal lamina not reaching leaf base, a single row of chlorophyllous cells present outside border towards base of sheathing laminae; costa ending below apex; cells irregular in shape and size, 6–15 μm wide in middle of apical lamina, not protuberant. Perichaetial bracts longer and narrower than stem leaves, 4–6 times as long as wide, acute to obtuse, border ending below to ± reaching apex but not confluent with costa; costa ending below apex. When autoicous, antheridia borne on short basal branches. Archegonia (250−)290–350(−440) μm long. Sporophytes terminal; setae red; capsules erect and symmetrical; peristome teeth (24−)30–47(−53) μm wide at base; spores 10–19 μm. Capsules common, late summer to spring. n = 10, 12. On dry or wet chalk, limestone or sandstone, sometimes completely submerged in fast-flowing streams or rivers. Frequent or common in basic areas, rare elsewhere. 81, H23. Europe north to southern Sweden, Turkey, Japan, Azores, Madeira. Some authors treat aquatic plants as F. pusillus and plants on terrestrial rocks as F. gracilifolius. However, in F. pusillus there is a complete intergradation from large aquatic forms, approaching F. crassipes in size, to smaller plants on both aquatic and terrestrial rocks. Furthermore, whilst F. gracilifolius in its typical form is very distinctive and occurs on dry rocks, a habitat also sometimes occupied by F. pusillus, it intergrades considerably with F. pusillus and can only be regarded as a very poorly defined species. Large aquatic forms of F. pusillus may be difficult or impossible to distinguish from small plants of F. crassipes unless fertile, although the cells of the dorsal lamina tend to be shorter. If capsules or archegonia are present then width of peristome teeth, spore size and archegonium length are distinctive.

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5 F. gracilifolius Brugg.-Nann. & Nyholm in Nyholm, Ill. Fl. Nord. Mosses, 1987 (Fig. 73) F. pusillus var. tenuifolius Boulay, F. viridulus var. tenuifolius (Boulay) A. J. E. Sm. Autoicous. Plants dark green, gregarious. Fertile plants mostly 1.5–2.5(−3.5) mm long with 2–4 or rarely more pairs of leaves. Leaves narrowly lanceolate, acute. Perichaetial leaves linear-lanceolate, 7–9 times as long as wide, acuminate, border reaching apex and confluent with costa; costa usually excurrent. Capsules similar to those of F. pusillus but sometimes two per perichaetium; spores 9–14 μm. On dry chalk, especially small pieces, limestone and calcareous sandstone in woodland and sheltered habitats. Lowland. Frequent in calcareous habitats in southern and central England, rare elsewhere, extending north to Perth and Kintyre, rare in Ireland. 53, H9. GB166 + 30∗ , IR6 + 4∗ . Widespread but rare in Europe, extending from the Mediterranean to S. Scandinavia, Turkey, Japan, Azores, Madeira. A poorly defined species which might be better treated as a variety of F. pusillus.

¨ 6 F. incurvus Starke ex Rohl., Deutschl. Fl (ed. 2) Kryptog. Gew., 1813 ¨ F. bryoides ssp. incurvus (Starke ex Rohl.) Bertsch

(Fig. 74)

Autoicous or dioicous. Dark green patches or scattered plants. Fertile shoots decumbent, 2–5(−10) mm long with 3–12 pairs of leaves. Leaves oblonglanceolate to lanceolate, cuspidate; margins entire; all laminae bordered, border pale, unistratose, usually confluent with percurrent costa, not reaching base of dorsal lamina; cells irregular in shape and size, 6–10 μm wide in middle of apical lamina. Perichaetial leaves narrower, more acute. When autoicous, antheridia borne on small branches at base of female shoots. Sporophytes terminal; setae red; capsules inclined to horizontal, asymmetrical, often curved; spores 12–16 μm. Capsules common, winter, spring. n = 4. On soil on arable and waste ground, banks, in open or sheltered situations. Lowland. Common in calcareous areas of lowland England, occasional in other parts of England and Wales, very rare in N. England and Scotland, extending north to Arran and Angus, rare in Ireland. 78, H14, C. GB382 + 90∗ , IR6 + 8∗ , C1 + 1∗ . Submediterranean-Subatlantic. Europe from the Mediterranean north to S. Scandinavia, Caucasus, Syria, N. Asia, Macaronesia, Africa, N, America, Australia. F. incurvus differs from F. bryoides in the inclined to horizontal, frequently curved capsules and the antheridia on short basal branches. The capsules tend to become horizontal when empty, but plants with the gametophyte of F. incurvus and erect capsules similar to those of F. viridulus confuse the distinctions between the two species. However, it is likely that such plants are erect-capsuled forms of F. incurvus rather than intermediates.

7 F. bryoides Hedw., Sp. Musc. Frond., 1801 (Fig. 74) Autoicous. Dark green patches. Fertile plants procumbent to ± erect, 3–20 mm long with 3–10 pairs of leaves, sterile shoots sometimes longer. Rhizoids few,

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Fig. 74 1–2, Fissidens incurvus: 1, plant; 2, stem leaf (×40). 3–6, F. exiguus: 3, plant; 4, perichaetial bract (×40); 5, margin of sheathing lamina of perichaetial bract; 6, leaf apex. 7–9, F. bryoides: 7, plant; 8, stem leaf (×40); 9, stem leaf apex. 10–11, F. curnovii: 10, leaf with axillary male branch (×20); 11, stem leaf apex. Plants ×10, cells ×320.

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brownish. Leaves oblong to lanceolate, 3–5 times as long as wide, cuspidate; border colourless, usually unistratose but sometimes 2(−3)-stratose, usually confluent with percurrent to excurrent costa, reaching stem at base of dorsal lamina; cells ± regularly hexagonal, 8–12(−14) m wide in middle of apical lamina. Perichaetial leaves longer and more acute than stem leaves, border confluent with percurrent or excurrent costa. Antheridia in gemmiform axillary shoots, rarely naked in leaf axils. Sporophytes terminal; setae red; capsules erect, ellipsoid; spores 10–14 μm. Capsules common, winter, spring. n = 5, 10, 12. On neutral to acid soil or more rarely on wood or stones in open places, arable fields, gardens, woods, on banks. 0–580 m. Capsules common, winter, spring. Occasional in N. E. Scotland, common or very common elsewhere, frequent in Ireland. 112, H36, C. GB1513 + 83∗ , IR150 + 6∗ , C7. Circumpolar Temperate. Europe, extending north to Svalbard, Azores, Madeira, N. Africa, Camaroon, Madagascar, N. America, southern S. America, New Zealand, Prince Edward Is. F. bryoides is usually readily distinguished from other small terrestrial Fissidens species by the leaves with the border confluent with the costa and the ± regularly hexagonal cells and the dwarf axillary male branches. F. curnovii differs in the larger spores and the stems usually with a dense tomentum of deep red or occasionally brownish rhizoids. F. monguillonii differs in habitat and has very narrow perichaetial leaves.

8 F. curnovii Mitt., J. Linn. Bot. Soc., 1885 F. bryoides var. caespitans Schimp.

(Fig. 74)

Autoicous. Dark green patches or scattered plants. Plants (4−)6–20 mm long with (3–4)-numerous pairs of leaves. Stems matted below with tomentum of deep red or occasionally brown rhizoids. Leaves oblong to lanceolate, cuspidate; border 2–3-stratose, colourless, confluent with percurrent to excurrent costa, reaching stem at bass of dorsal lamina; cells 8–12(−14) μm wide in middle of apical lamina. Perichaetial leaves longer than stem leaves. Antheridia in dwarf axillary shoots. Sporophytes terminal; setae red; capsules usually inclined but occasionally erect, ellipsoid; spores 16–20 μm. Capsules common, late spring, summer. On moist acidic soil, flushed rocks and in moist rock crevices by streams and rivers ± at normal water level, and on coastal cliffs. Lowland. Occasional to frequent in S. W. England, W. Wales, Lake District, I. of Man, extreme west of Scotland, very rare elsewhere, Lancashire, Mid-West Yorkshire, N. Northumberland, Sutherland, occasional in W. Ireland. 36, H12, C. GB166 + 18∗ , IR23 + 28∗ , C1∗ . Oceanic Southerntemperate. Belgium, Czechoslovakia, France, Italy, Portugal, Spain, Switzerland, Sicily, Macaronesia, N. Africa. F. curnovii is treated by continental European authors as a variety of F. bryoides, but although occasional intermediates do occur, it is sufficiently distinct to be treated as a species and is certainly a much stronger taxon than F. gracilifolius. F. curnovii is usually characterised by the dense tomentum of deep red rhizoids but occasional populations occur with brown rhizoids. If such plants are small and sterile they cannot be distinguished from F. bryoides on

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morphological grounds, but the habitat gives an indication of its identity. For a discussion of rhizoid colour see D. T. Holyoak & H. L. K. Whitehouse, J. Bryol. 20, 103–8, 1998.

9 F. rivularis (Spruce) Schimp. in Bruch et al., Bryol. Eur., 1851 (Fig. 75) Autoicous. Dark green, sometimes silt-encrusted patches or scattered plants; plants 7–20 mm long. Rhizoids brownish. Leaves numerous, lingulate to lingulatelanceolate, acute to obtuse and mucronate; border very stout, yellowish, confluent with excurrent costa at apex and forming stout mucro, reaching stem at base of dorsal lamina; cells 8–10 μm wide in middle of apical lamina. Perichaetial leaves hardly differing from stem leaves. Antheridia in gemmiform axillary branches. Sporophytes terminal; setae red; capsules erect or slightly inclined, ellipsoid; spores 17–20 μm. Capsules occasional, winter. Shaded moist or submerged neutral or acidic rocks, rarely on limestone, in streams, rivers and by lakes. Lowland. Occasional in Cornwall, Devon, S. Somerset, S. Wales, very rare elsewhere in widely scattered localities from N. Somerset east to E. Sussex and north to Kirkcudbright and Kintyre, N. Kerry, Jersey. 18, H1, C. GB28 + 2∗ , IR1, C1∗ . MediterraneanAtlantic. From Portugal east to Azerbaijan and north to S. Sweden, La Palma, Tenerife, Azores, Algeria. Readily distinguished from all other aquatic Fissidens species by the very stout yellowish border confluent with the excurrent costa and forming a stout mucro. In some localities this species appears tolerant of some degree of aquatic pollution.

´ Bull. Soc. Agric. Sarthe, 1899 10 F. monguillonii Ther., ´ Podp. F. rivularis var. monguillonii (Ther.)

(Fig. 75)

Autoicous or dioicous. Dull green, often silt-encrusted patches or scattered plants. Plants 4–25 mm long with up to 20 pairs of leaves. Rhizoids few, brownish. Stem leaves oblong to lingulate-lanceolate, obtuse and often mucronate; margins obscurely denticulate above; border well developed, ± colourless, 2–3-stratose, ± confluent with percurrent costa, reaching stem at base of dorsal lamina; cells (8−)9–14 μm wide in middle of apical lamina. Perichaetial leaves very narrow, linear-lanceolate, 6–12(−15) times as long as wide, markedly differing from preceding stem leaves. Antheridia in gemmiform axillary shoots, on short lateral branches or on separate plants. Sporophytes terminal or on short ventral branches; setae red; capsules ellipsoid, inclined; spores 14–18 μm. Capsules occasional, winter. On silt-covered rocks, rock ledges and tree roots on damp soil by lakes, on muddy banks at or below flood level of slow-flowing rivers and on bases of Phragmites stems in fens. Lowland. Very rare, E. Cornwall, Devon, S. Somerset, Carmarthen, Pembroke, Caernarfon, Anglesey, Leitrim, Cavan, Fermanagh. 8, H3. GB11, IR3. Oceanic Southern-temperate. Belgium, France, Spain, Azores. Distinguished from species 5–8 by the larger leaf cells and markedly differentiated perichaetial leaves. The border confluent with the costa will distinguish this plant from F. crassipes, and F. rufulus and the latter and F. pusillus have smaller cells; furthermore, these

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Fig. 75 1–4, Fissidens monguillonii: 1, plant (×10): 2, stem leaf; 3, perichaetial bract; 4, stem leaf apex. 5–7, F. rivularis: 5, plant (×5); 6, stem leaf; 7, stem leaf apex. 8–10, F. crassipes: 8, plant (×5); 9, stem leaf; 10, stem leaf apex. 11–12, F. rufulus: 11, stem leaf; 12, stem leaf apex. Leaves ×20, apices ×320.

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three species occur in fast-flowing water. For the occurrence of this plant in Britain see A. H. Norkett, Trans. Br. Bryol. Soc. 2, 11–14, 1952.

11 F. crassipes Wilson ex Bruch & Schimp. in Bruch et al., Bryol. Eur., 1849 (Fig. 75) F. mildeanus Schimp. ex Milde Dioicous. Dark green patches or scattered ± decumbent plants, 7–20 mm long, with numerous pairs of leaves. Rhizoids few, brownish. Leaves lanceolate to narrowly lanceolate, acute; margins obscurely denticulate above; border 2–4-stratose, colourless to reddish, ending below apex, border of dorsal lamina ending before leaf base; costa ending in apex; cells thin-walled to incrassate, (6−)10–14(−18) μm wide in middle of apical lamina. Perichaetial bracts ± similar to stem leaves. Archegonia 420–600 μm long. Sporophytes terminal; setae red; capsules ellipsoid, erect or inclined; peristome teeth 51–86 μm wide at base; spores 18–28 μm. At or below normal water level on usually but not necessarily basic rocks in sometimes somewhat polluted streams and rivers and on canal sides. Lowland. Occasional to frequent throughout England, E. Wales and S. Scotland, extending north to Kintyre and Skye, occasional throughout Ireland. 72, H21. GB284 + 76∗ , IR26 + 2∗ . European Southern-temperate. Europe north to southern Finland and Sweden, Turkey, Asia, Canary Islands, Azores, N. and C. Africa, Australia. Some of the characters used to distinguish F. crassipes and F. rufulus – presence or absence of intralaminal border at base of the sheathing laminae, and the reddish border in F. rufulus – are unreliable. The most useful distinguishing characters are leaf cell size, archegonium length and peristome tooth width. In F. crassipes the border of the dorsal lamina does not reach the stem and the leaf apex is narrower. Small plants of F. crassipes are very similar to large aquatic plants of F. pusillus (q.v.).

12 F. rufulus Bruch & Schimp. in Bruch et al., Bryol. Eur., 1851 (Fig. 75) Dioicous. Dark green patches, plants ± decumbent, to 20 mm long with numerous leaves. Rhizoids few, brownish. Leaves oblong-lanceolate to lingulate-lanceolate, apex broad, ± obtuse; border strong, often orange or red, not reaching apex, border of dorsal lamina extending to leaf base; costa ending in apex; cells 8–10(−12) μm wide in middle of apical lamina. Perichaetial leaves ± similar to stem leaves. Archegonia 300–400(−560) μm long. Sporophytes terminal; setae red; capsules ellipsoid, erect or inclined; peristome teeth (37−)43–66(−71) μm wide at base; spores 18–22 μm. Capsules occasional, winter. On rocks ranging from acidic to limestone at or below normal water level in unpolluted fast-flowing streams and rivers. 0–300 m. Occasional in S. W. Wales, N. England and southern Scotland, very rare elsewhere, Worcester, E. Perth, Angus, rare in Ireland. 20, H6. GB47 + 10, IR7 + 3∗ . European Temperate. Rare in W., C. and S. Europe. 13 F. exilis Hedw., Sp. Musc. Frond., 1801 (Fig. 76) Autoicous or dioicous. Plants ephemeral, in pale green thin patches or scattered, decumbent, 1.5–3.0 mm long with 2–4 pairs of leaves. Leaves lingulate to narrowly

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Fig. 76 1–3, Fissidens exilis: 1, plant (×10); 2, leaf (×40); 3, leaf apex. 4–6, F. celticus: 4, plant (×10); 5, leaf (×40); 6, leaf apex. 7–9, F. curvatus: 7, plant (×10); 8, leaf (×40); 9, leaf apex. 10–12, F. osmundoides: 10, plant (×5); 11, leaf (×30); 12, leaf apex. Apices ×320.

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lanceolate, acute; margins unbordered, crenulate or crenulate-serrulate; costa ending in apex; cells 8–12(−14) μm wide in middle of apical lamina. Perichaetial leaves ± similar to stem leaves. Male branches gemmiform at base of female stems or antheridia on separate plants. Sporophytes terminal; setae red; capsules erect, ellipsoid to subcylindrical; spores 10–12 μm. Capsules common, autumn to spring. n = 12. On loam or clay soil in woodland, on sheltered banks and stream sides and in damper parts of fields and grassland. Lowland. Occasional to frequent in southern Britain, rare or very rare in the north, extending to Caithness, rare in Ireland. 83, H10, C. GB284 + 18∗ , IR4 + 8∗ , C2∗ . European Temperate. Europe, extending to about 62◦ N, Turkey, Kashmir, N. Asia, Japan, La Gomera, Algeria, eastern N. America. 14 F. celticus Paton, Trans. Brit. Bryol. Soc., 1965 (Fig. 76) Dioicous. Dull green patches or scattered plants. Plants ± erect, 2.5–4.6 mm long with up to 14(−18) pairs of leaves. Deep red rhizoids at base of stems. Leaves lingulate to lanceolate, acute; margins unbordered, crenulate with projecting cell walls; costa with distinct bend at about half way up leaf, percurrent; cells ± hexagonal, marginal row 8–12 μm wide, in middle of apical lamina 12–20 μm wide. Perichaetial leaves similar to but larger than stem leaves. Antheridia and sporophytes unknown. On shaded soil banks in woods and by streams. Lowland. Occasional to frequent in S. E. and S. W. England, W. Wales and W. Scotland from Kintyre to Skye, very rare elsewhere, Lake District, Kirkcudbright, Wigtown, rare in Ireland. 41, H12. GB189, IR13. (European Temperate). Endemic. Easily recognised in the field by the ± erect plants with numerous leaves, resembling miniature palm fronds. For details of this plant see J. A. Paton, Trans. Br. Bryol. Soc. 4, 780–4, 1965.

Section 2 Pycnothallia Mull. ¨ Hal., Gen. Musc. Frond., 1900 A heterogeneous group of species with bordered leaves and papillose cells. 15 F. curvatus Hornsch., Linnaea, 1841 F. algarvicus Solms

(Fig. 76)

Dioicous. Small patches or scattered decumbent plants, 1.5–3.0 mm long, fertile stems with 3–5 pairs of leaves, sterile stems with more. Leaves linear-lanceolate, gradually tapering from below middle to acuminate apex; all laminae bordered, border stout, wide, confluent with costa at apex; cells in upper part of leaf irregular, narrowly hexagonal, about twice as long as wide, papillose, 4–8 μm wide in apical lamina, cells in sheathing lamina larger. Male plants minute, bud-like. Sporophytes terminal; setae red; capsules erect, ovoid; spores c. 14 μm. Capsules occasional, winter, spring. On clayey soil on shaded banks. Lowland. Very rare, sporadic in appearance, Cornwall, S. Devon, E. Gloucester, Radnor, Pembroke,

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Merioneth, Caernarfon, S. Kerry. 8, H1. GB13 + 3∗ , IR2. Mediterranean-Atlantic. S. and W. Europe, Turkey, Macaronesia, N. Africa. Distinguished from other small terricolous Fissidens species with bordered leaves by the longly tapering leaves with elongate papillose cells but possibly overlooked because of its small size and sporadic occurrence in small quantity.

Section 3 Serridium Mull. ¨ Hal., Gen. Musc. Frond., 1900 Plants medium-sized to robust. Leaf laminae unbordered; margins crenulate or serrate; cells smooth. 16 F. osmundoides Hedw., Sp. Musc. Frond., 1801 (Fig. 76) Dioicous. Dense bright to dark green erect tufts, to 10 cm high. Leaves numerous, lingulate-lanceolate to oblong-lingulate, acute to subobtuse and apiculate; margins regularly crenulate, unbordered; costa ending below or in apex; cells incrassate, variable in size, 12–22 μm wide in middle of apical lamina. Light to dark brown or blackish irregularly-shaped rhizoidal gemmae, to 1500 μm long, sometimes present. Sporophytes terminal; setae purple; capsules erect or inclined, ellipsoid; spores 18–24 μm. Capsules occasional, winter. n = 12, 16. On moist rock ledges and crevices on cliffs and in ravines, often where slightly basic, by mountain streams and flushes. 0–920 m. S. Hampshire, frequent or common in western and northern Britain, and in montane parts of Ireland. 67, H31. GB503 + 35∗ , IR77 + 13∗ . Circumpolar Boreo-arctic Montane. Europe north to Svalbard, Faeroes, Iceland, Siberia, C. Asia, Japan, Malaya, Azores, N. America, Greenland, southern S. America. Distinguished from other species with unbordered leaves by the terminal sporophytes with purple setae, the relatively shorter and wider leaves and the usually wider cells. F. taxifolius has a percurrent or excurrent costa and in the other species the margins are variously toothed. For an account of rhizoidal gemmae in F. osmundoides, F. polyphyllus and F. serrulatus see T. Arts, Lindbergia 14, 151–4, 1988.

17 F. taxifolius Hedw., Sp. Musc. Frond., 1801 Autoicous. Light green to reddish brown patches, sometimes extensive. Shoots procumbent to erect, to 2(−3) cm long, branching from base, old stems rhizome-like, tomentose. Leaves numerous, lingulate-lanceolate or rarely linearlanceolate; margins unbordered, crenulate or serrulate, sometimes finely so; costa strong, percurrent or excurrent; cells 6–10 μm wide in middle of apical lamina, marginal row smaller, often more pellucid. Sporophytes axillary near base of main branches; setae red; capsules usually horizontal, ellipsoid; spores 12–18 μm. Capsules occasional to frequent, winter to spring. Leaves lanceolate-lingulate, acute or obtuse and apiculate, margins crenulate or serrulate var. taxifolius Leaves lanceolate to linear-lanceolate, acuminate; margins finely crenulate or finely serrulate var. pallidicaulis

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14 Fissidentaceae

Var. taxifolius (Fig. 77) Shoots mostly 1–2 cm long. Leaves lanceolate-lingulate, ± shortly tapering to acute or obtuse and apiculate apex; margins crenulate or serrulate; cells 6–10 μm in middle of apical lamina. Dark brown to blackish rhizoidal gemmae, irregular in shape, 300–700 μm diameter, sometimes present. n = 9, 10, 12∗ , 12 + m∗ , 16. On basic to acidic, especially clayey soils, on rocks, in rock crevices, in woods, arable fields, gardens, on banks, by ditches and streams. 0–460 m. Very common except in N. E. Scotland. 112, H40, C. GB1744 + 69∗ , IR257 + 5∗ , C3 + 1∗ . European Southerntemperate. Europe to about 64◦ N, Faeroes, Turkey, Caucasus, Asia, Macaronesia, Tunisia, the Americas, New Zealand. Var. pallidicaulis (Mitt.) Corb. in Pitard & Negri, M´em. Soc. Bot. France, 1907 (Fig. 77) ¨ F. pallidicaulis Mitt. F. taxifolius ssp. pallidicaulis (Mitt.) Monk. Shoots 2–3 cm long. Leaves mostly lanceolate to linear-lanceolate, tapering from end of sheathing lamina to acuminate apex; margins finely crenulate or finely serrulate; cells 7–9 μm wide in middle of apical lamina. Capsules unknown in the British Isles. On damp soil on rocky stream banks. Rare but widely dispersed from S. Devon and S. Hampshire north to Shetland, rare in Ireland. 22, H5. Oceanic Southern-temperate. S. and W. Europe north to France, Macaronesia, C. America. For an account of var. pallidicaulis in the British Isles see E. C. Wallace, J. Bryol. 9, 161–2, 1972. In its extreme form such as is found on Madeira, it is very distinctive with shoots up to 6 cm long and the leaves to 10 times as long as wide. The British and Irish plants are much less distinctive and only merit varietal status. The narrower and more closely set leaves of var. pallidicaulis may lead to confusion with F. polyphyllus but the smaller cells and excurrent costa are distinctive. Rhizoidal gemmae have only been found on sterile plants of var. taxifolius and the relationship between these and fertile plants requires investigation.

18 F. dubius P. Beauv., Prodr. Aeth´eogam., 1805 F. cristatus Wilson ex Mitt., F. decipiens De Not.

(Fig. 77)

Autoicous or dioicous. Dense dull green or brownish green tufts, to 6 cm high. Plants erect, older parts of stems often with eroded leaves, tomentose below, branches to 2(−3) cm long with numerous leaves. Leaves ovate-lanceolate to lanceolate, acute to obtuse and apiculate; margins crenate-serrate to irregularly toothed towards apex, unbordered; costa ending below apex or rarely excurrent; cells incrassate, opaque, bistratose in patches in upper part of leaf, mostly 8– 12 μm wide in middle of apical lamina, 3–4 marginal rows more incrassate and pellucid, forming pale marginal band. Sporophytes borne on dwarf branches arising from middle or base of stems; setae pale red; capsules ± horizontal, ellipsoid; spores 10–16 μm. Capsules occasional, winter, spring. n = 12∗ , 12 + m, 13 + 2m, 16. On shaded soil and rocks by streams, on cliffs and on soil in calcareous grassland, sand-dunes, occasionally on wood and in bogs. 0–760 m. Common in wetter parts of the British Isles but limited to calcareous sites elsewhere. 108, H39,

38 Fissidens

257

Fig. 77 1–4, Fissidens taxifolius var. taxifolius: 1, plant (×5): 2, leaves (×25); 3, apical lamina cells; 4, leaf apex. 5–6, F. taxifolius var. pallidicaulis: 5, leaf (×25); 6, apical lamina cells. 7–10, F. adianthoides: 7, plant (×4); 8, leaf (×15); 9, leaf apex; 10, section of apical lamina. 11–13, F. dubius: 11, leaf (×15); 12, leaf apex; 13, section of apical lamina. Cells ×320.

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14 Fissidentaceae

C. GB971 + 59∗ , IR183 + 5∗ , C2 + 1∗ . European Temperate. Europe to about 68◦ N, Faeroes, Iceland, Turkey, Caucasus, Manchuria, Japan, India, Java, Macaronesia, N. America, Mexico, Haiti. Close to F. adianthoides but usually distinguishable by the smaller leaf cells and more conspicuous marginal band of pale cells. Forms of F. adianthoides from dry ground may have smaller cells and may be difficult to separate, but have the leaf cells unistratose throughout. It seems possible that F. adianthoides is an autopolyploid derivative of F. dubius. According to T. Arts (Lindbergia 12, 119–20, 1986), reddish-brown to black or occasionally paler, spherical to irregularly-shaped rhizoidal gemmae, 80–500(−1000) × 100–600(−1600) μm, are often present in F. dubius.

19 F. adianthoides Hedw., Sp. Musc. Frond., 1801 (Fig. 77) Autoicous or dioicous. In dense yellowish green to dark green tufts, to 10(−25) cm high. Plants decumbent to erect, branches to 5(−7) cm long with numerous leaves. Leaves broadly lingulate to lingulate-lanceolate, acute to obtuse and apiculate; margins crenulate below, sharply and irregularly toothed above, unbordered; costa ending in or below apex; cells opaque, incrassate, unistratose throughout, 12– 20 μm wide in middle of apical lamina, 3–4 marginal rows more incrassate, pellucid, forming pale marginal band. Sporophytes borne on dwarf branches arising from middle of stems; setae reddish; capsules, erect or inclined, ellipsoid, straight or curved; spores 18–24 μm. Capsules frequent, autumn to spring. n = 24∗ . In damp or wet situations on ledges and in crevices on cliffs, in flushes, fens, ditches, dune-slacks, also in chalk and limestone grassland, rarely on wood, a calcicole when in drier habitats. 0–950 m. Common in wetter parts of the British Isles but frequent only on chalk and limestone in lowland England. 112, H38, C. GB1106 + 130∗ , IR215 + 8∗ , C1 + 1∗ . Circumpolar Boreo-temperate. Europe north to Svalbard, Faeroes, Iceland, Japan, Hong Kong, Azores. Madeira, N. America, Tierra del Fuego. Recognisable on sight in montane and moist habitats, having relatively wider shoots with longer pale-bordered toothed leaves than F. osmundoides, which has terminal sporophytes. Small forms may be confused with F. dubius (q.v.).

20 F. serrulatus Brid., Sp. Musc. Frond., 1806 (Fig. 78) Dioicous. Loose green tufts or patches, plants to 7.5 cm long, stems procumbent to erect, simple or branched. Leaves numerous, oblong-lanceolate to lingulate, acuminate to obtuse or obtuse and apiculate; margins crenulate below, irregularly toothed above, unbordered; costa ending in or below apex; cells incrassate, conically mamillose, partially bistratose, 10–16 μm wide in middle of apical lamina, 3–4 marginal rows more incrassate, pellucid, forming pale marginal band. Spherical or irregular, reddish brown to blackish rhizoidal gemmae, to 800 μm diameter, often present. Sporophytes terminal; setae yellowish; capsules inclined, ovoid. Only male plants known in the British Isles. On alluvial sand and gravel and on rocks below flood level of deeply shaded streams in ravines. Lowland.

38 Fissidens

259

Fig. 78 1–3, Fissidens serrulatus: 1, leaf (×5); 2, section of apical lamina (×320); 3, leaf apex (×320). 4–5, F. polyphyllus: 4, leaf (×5); 5, leaf apex (×320). 6–8, Octodiceras fontanum: 6, plant (×5); 7, leaf (×14); 8, leaf apex (×320). 9–12, Schistostega pennata:, 9, 10, sterile and fertile shoots (×10); 11, leaf (×20); 12, calls from upper part of leaf (×320).

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14 Fissidentaceae

Very rare, W. Cornwall, S. Devon, Merioneth, S. Kerry, W. Mayo. 3, H2. GB4, IR2. Mediterranean-Atlantic. Corsica, France, Greece, Italy, Portugal, Spain, Yugoslavia, Macaronesia, Tunisia, Algeria. Similar to F. adianthoides but with smaller conically mamillose cells. F. polyphyllus has narrower leaves with smooth cells and no pale marginal band. The mamillae are most easily seen in side view on a folded leaf. This species is treated as vulnerable in the Red List of British Mosses.

21 F. polyphyllus Wilson ex Bruch & Schimp. in Bruch et al., Bryol. Eur., 1851 (Fig. 78) Dioicous or autoicous. Dark green tufts to extensive patches. Plants procumbent, to 20(−30) cm long. Leaves numerous, narrowly lingulate to narrowly lanceolate, acuminate, acute to obtuse and apiculate; margins finely and obscurely denticulate towards apex, unbordered and without a pale marginal band; costa ending in apex; cells pellucid, smooth, 8–14 μm wide in middle of apical lamina, single marginal row smaller. Irregularly shaped, reddish brown rhizoidal gemmae, to 800 μm long, sometimes present. Sporophytes borne on dwarf lateral branches on upper parts of stems; capsules inclined, ovoid; unknown in the British Isles. Damp shaded rocks and hard-packed soil by streams and waterfalls and on dripping rocks. Lowland. Rare, Cornwall, S. Devon, N. W. Wales, Argyll, Kintyre, Jura, Kerry, W. and Mid Cork, Waterford, Wicklow, Sligo. 9, H7. GB30 + 2∗ , IR5 + 5∗ . Hyperoceanic Southerntemperate. Western Europe north to S. W. Norway, Italy, Tenerife, Madeira, Azores.

39 OCTODICERAS BRID., MUSCOL. RECENT. SUPPL., 1806 Stems without central strand. Sheathing laminae 1/4 –1/3 total leaf length. Capsules ± immersed in perichaetial leaves, without stomata. About 15 species distributed through Europe, Asia and America. Derivation: meaning 8 double horns based on the erroneous assumption that there were 8 divided peristome teeth

¨ 1 O. fontanum (Bach. Pyl.) Lindb., Ofvers F¨orh. Kongl. Svenska Vetensk-Akad., 1863 (Fig. 78) O. julianum Brid., Fissidens fontanus (Bach. Pyl.) Steud. Autoicous. Submerged dull green patches. Plants to 3 cm long. Leaves distant, spreading, linear to linear-lanceolate, gradually tapering from near base to blunt apex; margins entire, unbordered; costa ending below apex; cells thin-walled to incrassate, c. 10 μm wide in middle of apical lamina, larger towards margins and base. Antheridia and archegonia terminal on short lateral branches. Capsules ± immersed, ellipsoid; unknown in the British Isles. On submerged wood, stones, concrete and man-made structures, on fresh-water sponges, from near the surface to 80 cm deep in sluggishly flowing, fresh or slightly polluted water in rivers

40 Schistostega

261

and canals. Lowland. Rare but sometimes locally abundant, from E. Cornwall, S. Wiltshire and N. Essex north to S. Lancashire and M. W. Yorkshire, Pembroke, W. Galway, Leitrim. 26, H2. GB19 + 19∗ , IR2. European Temperate. Europe from Portugal, Spain and Italy north to S. Sweden, Madeira, Africa, N. America, Mexico, Chile, Australia, New Zealand.

15 Schistostegaceae With the characters of the single species.

40 SCHISTOSTEGA D. MOHR, OBSER. BOT., 1803 Derivation: meaning split lid from the erroneous assumption that the capsule lid split.

1 S. pennata (Hedw.) F. Weber & D. Mohr, Ind. Mus. Pl. Crypt., 1803 S. osmundacea D. Mohr

(Fig. 78)

Pseudodioicous. Glaucous green patches, reddish brown below. Shoots variable in length, to 1.5 cm long. Stems flexuose, naked below, arising from persistent thalloid protonemata with light reflecting properties. Leaves on sterile stems in two ranks, ovate-lanceolate to lanceolate, confluent at base, acute to acuminate; margins plane, entire; costa lacking; cells thin-walled, rhomboidal, 16–30 μm wide in mid-leaf. Fertile stems similar to sterile stems or with leaves in rosette at apex. Obclavate protonemal gemmae, 80–200 × 15–20 μm and composed of 3–4 cells, usually present. Setae thin, to 4 cm long; capsules ovoid, gymnostomous; lid convex; spores 8–12 μm. Capsules occasional, spring, summer. n = 11∗ , 14. On deeply shaded, usually friable soil on lane banks, entrances to caves, old rabbit burrows and mine shafts, crevices between granite rocks. Lowland. Frequent in Cornwall and rare to occasional from Devon east to Surrey and north to W. Inverness, Jersey. 42, C. GB105 + 29∗ , C1. Suboceanic Boreo-temperate. Europe north to Fennoscandia, Amur, Japan, N. America. Because of the light refractive properties of the convex cells of the persistent protonemata this moss appears luminescent when growing in dark places such as the mouths of caves or rabbit holes.

9 Pottiales Acrocarpous. Leaves linear to spathulate, acuminate to rounded; costa in section with one or two stereid bands. Setae usually long; capsules cleistocarpous or dehiscent; peristome absent, rudimentary or well developed; teeth entire, perforated or bifid to base into filiform often spirally coiled segments. Six families.

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16 Pottiaceae

16 Pottiaceae Usually small plants, often with xeromorphic features. Leaves linear to spathulate or ovate, acuminate to rounded; margins entire to dentate, usually unbordered; costa usually strong, in section with one or two stereid bands; basal cells rectangular, ± hyaline, cells above hexagonal or quadrate, often papillose, sometimes obscure. Setae very short to long, usually straight; capsules erect or inclined, globose to cylindrical, straight or curved, cleistocarpous or dehiscent; peristome absent, rudimentary, imperfect or perfect, teeth straight or spirally coiled, entire, perforated or variously cleft or divided into filiform segments. About 80 genera. A diverse family, many species of which show strongly xeromorphic features, recently monographed by Zander (1993). The monograph is based upon detailed anatomical and morphological studies resulting in a radical reclassification of many genera and species. I have largely followed Zander in the division of the Pottiaceae into subfamilies and tribes. However, his classification is based upon cladistics and this appears to have misplaced some genera, as is indicated by recent DNA studies (see V. Spagnuolo et al., Pl. Syst. Evol. 216, 69–79, 1999), which show that Weissia should be in the Trichostomoideae and not in the Pottioideae, where Zander (1993) places it. That species of Weissia hybridise with Tortella supports this. In discussing subfamilies and tribes Zander talks in terms of clades and ancestral nodes rather than providing descriptions of the taxa concerned. For this reason some of his descriptions are extremely short and inadequate.

Subfamily 1 TRICHOSTOMOIDEAE Stems with sclerodermis poorly differentiated, hyalodermis usually present. Leaves lanceolate, basal part expanded or not; margins plane or narrowly recurved below, plane or incurved above; costa 4–6 cells wide, not grooved on adaxial side; basal cells often hyaline, sometimes extending up margins, cells above with crowded papillae. Perichaetial leaves not sheathing. Clavate axillary gemmae lacking.

41 EUCLADIUM BRUCH & SCHIMP. IN BRUCH ET AL., BRYOL. EUR., 1846 A monotypic genus with the characters of the species. Laminal KOH reaction yellow. Derivation: meaning repeatedly branched stems.

1 E. verticillatum (Brid.) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1846 (Fig. 79) Weissia verticillata Brid. Dioicous. Dense tufts, pale or glaucous green above, often encrusted with calcareous matter below mostly 0.5–3.0 cm high. Stems lacking central strand; rhizoids light brown. Leaves erect to erect-patent, flexuose when dry, patent to spreading

41 Eucladium

263

Fig. 79 1–4, Eucladium verticillatum: 1, leaves (×25); 2, mid-leaf cells; 3, marginal cells near leaf base; 4, capsule (×10). 5–8, Weissia controversa var. controversa: 5, stem and perichaetial leaves (×40); 6, adaxial side of costa at middle of leaf; 7, capsule (×20); 8, capsule mouth (×40). 9, W. controversa var. densifolia: leaf (×40). 10–11, W. controversa var. wimmeriana: 10, leaf (×40); 11, mid-leaf cells. Cells ×420.

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when moist, linear or linear-lanceolate from ± expanded basal part, acute; margins plane, toothed near base, finely papillose-crenulate above; costa ending below apex to shortly excurrent, adaxial cells quadrate to elongate; basal cells narrowly rectangular, hyaline, cells above rectangular to quadrate, incrassate, papillose, pellucid, c. 10 μm wide in mid-leaf. Setae straight, long, reddish. Capsules erect, ovoid to ellipsoid; lid longly rostrate, oblique; peristome teeth oblique, nodulose, irregularly cleft or perforated; spores 12–14 μm. Capsules rare, spring. n = 13∗ . On damp or wet shaded base-rich rocks, especially limestone, on cliffs, in ravines, by streams, waterfalls, in flushes, sometimes forming tufa, also on drier rock in woodland. Lowland. Occasional to common throughout the British Isles. 107, H38, C. GB476 + 75∗ , IR63 + 13∗ , C1∗ . European Southern-temperate. Europe north to Scandinavia, Caucasus, Turkey, Cyprus, Asia, Macaronesia, Africa, N. and C. America. Plants growing in deeply shaded habitats produce protonemal gemmae, 40–50 × 25–30 μm, but these are lacking in colonies occurring where light is brighter (see H. L. K. Whitehouse, J. Bryol., 11, 133–8, 1980).

42 WEISSIA HEDW., SP. MUSC. FROND., 1801 Usually autoicous. Small plants, frequently with much-branched stems. Leaves curled or crisped when dry, erect-patent to spreading when moist, increasing in size up stems, narrowly lanceolate to linear-lanceolate, acute to acuminate; margins plane, incurved or involute above, entire or papillose-crenulate, sometimes minutely toothed near base of perichaetial leaves; costa stout, ending below apex to excurrent, 4–8(−10) cells wide on adaxial side, cells quadrate or elongate, in section with two stereid bands; basal cells ± rectangular, hyaline, cells above rounded-quadrate, strongly papillose, opaque or pellucid. Perichaetial leaves similar to or larger than stem leaves. Setae straight, long or short; capsules dehiscent or cleistocarpous; lid or beak usually longly rostrate, oblique; peristome teeth short, rudimentary or absent, teeth when present usually 16, variously cleft or perforated; epiphragm present or not; calyptrae cucullate. Laminal KOH reaction yellow. A world-wide genus of c. 125 species. Derivation: named after the German botanist F. W. Weis (or Weiss), 1744–1826. Weissia as recognised here is divided by some authors into two or three genera: Weissia (species 1–4), Hymenostomum R. M. Brit. (species 5–8) and Astomum Hampe (species 9–13). The difference between the first two is presence or absent of peristome and epiphragm but in the presence of intermediates these taxa hardly merit generic status. Astomum is based on the operculum absent or poorly defined and the capsules indehiscent. W. levieri has dehiscent capsules and in W. longifolia var. angustifolia the capsules dehisce under pressure. On this evidence Astomum cannot be maintained as a separate genus. Different species of Weissia and Tortella sometimes occur in mixed populations and the following hybrids have been recorded: W. controversa × W. longifolia,

42 Weissia

265

W. longifolia × W. controversa, W. controversa var. crispata × W. longifolia, W. longifolia × W. controversa var. crispata, W. controversa × W. brachycarpa, Tortella flavovirens × W. longifolia (female parent cited first).

1 Setae longer than capsules 2 Setae shorter than or as long as capsules 9 2 Capsules with at least a rudimentary peristome, epiphragm lacking 3 Capsules without peristome, epiphragm present or capsules cleistocarpous 5 3 Margins of upper and perichaetial leaves plane or only narrowly incurved, spores 22–28 μm 3. W. rutilans Margins of upper and perichaetial leaves involute, spores 16–20 μm 4 4 Adaxial cells of costa papillose, quadrate at least in patches in upper half of leaf 1. W. controversa Adaxial cells of costa smooth, elongate in upper half of leaf 2. W. perssonii 5 Setae 1.5–7.0 mm long, operculum not persisting at maturity of capsules 6 Setae 0.7–1.7 mm long, capsules cleistocarpous 8 6 Costa 60–120 μm wide near leaf base, spores 14–20 μm 4. W. condensa Costa to 55 μm wide near leaf base, spores 20–34 μm 7 7 Plants forming dense tufts or patches, lacking distant-leaved innovations, leaves patent when moist, exothecial cell walls thick 5. W. brachycarpa Plants forming lax patches, distant-leaved innovations arising from below perichaetia, leaves spreading to recurved when moist, exothecial cells very thin-walled 6. W. squarrosa 8 Plants to 5 mm high, perichaetial leaves 1.9–2.2 mm long, similar to upper stem leaves, spores normal 7. W. rostellata Plants to 15 mm high, perichaetial leaves 3–4 mm long, distinctly longer than stem leaves, spores often aborted W. × mittenii (p. 273) 9 Fertile stems usually with clustered short branches, sporophytes often two or more per perichaetium 9. W. sterilis Fertile stems hardly branched, rarely more than one sporophyte per perichaetium 10 10 Capsules dehiscent in nature, spores finely papillose 10. W. levieri Capsules indehiscent in nature, spores finely or coarsely papillose 11 11 Fertile plants c. 15 mm high, leaves crisped when dry, transition from spreading stem leaves to erect perichaetial leaves abrupt spores finely papillose 8. W. multicapsularis Fertile plants c. 10 mm high, leaves strongly curled when dry, transition from stem to perichaetial leaves not abrupt, spores coarsely papillose 11. W. longifolia Section 1 Weissia Setae longer than capsules; capsules exserted, ovoid to narrowly ellipsoid, dehiscent; peristome present; epiphragm lacking.

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1 W. controversa Hedw., Sp. Musc. Frond., 1801 Yellowish green to dark green tufts or patches, 5–40 mm high. Leaves crisped when dry, patent to spreading when moist, from oblong-lanceolate basal part abruptly narrowed into linear-lanceolate limb, apex acute and often mucronate; margins plane, entire below, strongly involute above; costa stout, excurrent, adaxial cells in upper half of leaf quadrate at least in patches; basal cells rectangular, hyaline, cells above quadrate-hexagonal, papillose, obscure. Setae yellowish, (1.5−)2.0– 6.0 mm long; capsules erect or slightly inclined, ovoid to narrowly ellipsoid, symmetrical or slightly asymmetrical, narrowed at mouth, smooth or slightly furrowed when dry and empty; lid longly rostrate; peristome teeth poorly developed or rudimentary, to 100 μm long; spores 16–20 μm. Capsules common, winter, spring. 1 Costa reddish, (60−)70–100 μm wide near base var. crispata Costa greenish, 30–50(−65) μm wide near base 2 2 Plants synoicous, widespread 3 Plants paroicous, very rare montane plant var. wimmeriana 3 Plants mostly 3–10 mm high, upper leaves larger and more crowded than lower, setae usually 2–6 mm long var. controversa Plants 15–40 mm high, leaves of ± uniform length and distribution along stems, setae c. 1.5 mm long var. densifolia

Var. controversa (Fig. 79) Autoicous. Dull green or yellowish green tufts or patches, sometimes extensive, 3–10 mm high. Lower leaves short, distant, upper longer, more crowded; costa 30– 60(−65) μm wide near base. Setae (1.5−)3.0–6.0 mm long, n = 11, 13∗ , 13 + m, 14. On light soil in turf, on banks, walls, roadsides, cliffs, sand-dunes and among rocks, in usually but not always exposed habitats. 0–550 m. Frequent or common except in eastern England and N. W. Scotland, frequent in Ireland. 112, H39, C. GB982 + 121∗ , IR172 + 4∗ , C8 + 1∗ . Circumpolar Wide-temperate. More or less cosmopolitan. Var. crispata (Nees & Hornsch.) Nyholm, Ill. Moss Fl. Fennoscandia. 2. Musci, fasc. 6, (Fig. 79) W. controversa var. fallax (Sehlm.) R. H. Zander, W. crispata (Nees & Hornsch.) ¨ Hal., W. fallax Sehlm. Mull. Autoicous. Lax yellowish green tufts. Costa reddish, stout, (60−)70–100 μm wide near leaf base. n = 12∗ . On banks, in chalk and limestone grassland, on cliffs, calcicole. Lowland. Rare but widely distributed from Cornwall east to Surrey and north to Berwick and Roxburgh. 18. GB14 + 6∗ . Circumpolar Wide-temperate. From Mediterranean Europe north to Scandinavia, Faeroes, Caucasus, Turkey, Asia. Macaronesia, N. Africa, N. America.

42 Weissia

267

Var. densifolia (Bruch & Schimp.) Wilson, Bryol. Brit., 1855 (Fig. 79) Autoicous. Very dense dark green tufts or patches, sometimes extensive, 15– 40 mm high. Leaves of uniform size and distribution along stems. Setae c. 1.5 mm long. n = 13∗ . On soil, especially associated with heavy-metal mine workings. Lowland. Rare in western Britain from Cornwall north to Cumberland and I. of Man, Berwick, W. Lothian, Mid Perth, S. Kerry, N. Tipperary, Fermanagh. 22, H3. GB42 + 13∗ , IR2 + 1∗ . European Temperate. Rare in Europe, N. Africa. Var. wimmeriana (Sendtn.) Blockeel & A. J. E. Sm., J. Bryol., 1998 W. wimmeriana (Sendtn.) Bruch & Schimp.

(Fig. 79)

Paroicous. Antheridia 2–3 together with paraphyses in the axils of leaves below the perichaetium. On soil among rocks. 500 m. Very rare, E. Inverness. 1. GB1. European Boreal-montane. Montane Europe north to Scandinavia, Iceland, Caucasus, Turkey, Kashmir. W. controversa is more widespread than W. brachycarpa, which is more strongly calcicole. The two can only be distinguished when mature capsules are present, the presence of poorly developed peristome teeth and absence of an epiphragm being characteristic of the former. Although var. wimmeriana is usually treated as a species, the only consistent difference between it and var. controversa is that the former is paroicous and on these grounds it cannot be considered as more than a variety. For an account of the occurrence of var. wimmeriana in Scotland see E. F. Warburg, Trans. Brit. Bryol. Soc. 3, 171–3, 1957.

2 W. perssonii Kindb., Bot. Not., 1898 W. controversa ssp. perssonii (Kindb.) Podp.

(Fig. 80)

Dull green or yellowish green patches, to 10 mm high. Leaves strongly crisped when dry, patent to spreading when moist, from oblong-lanceolate basal part abruptly narrowed to linear-lanceolate upper part, acute; margins plane, entire below, involute above; costa (45−)50–70 μm wide near base, adaxial cells in upper half of leaf elongate, not papillose; basal cells hyaline, cells above quadratehexagonal, incrassate, papillose, obscure. 9–10 μm wide in mid-leaf. Setae 2–5 mm long; capsules ovoid or ellipsoid, strongly contracted at mouth, smooth when dry and empty; epiphragm lacking; peristome teeth rudimentary, 20–50 μm long; spores 16–20 μm. n = 13∗ . By the coast on soil on cliffs and cliff tops and in rock crevices on calcareous or non-calcareous substrates. Lowland. Occasional along the west coast from Cornwall to Shetland, Monmouth, very rare in W. and N. Ireland. 25, H6, C. GB60 + 2∗ , IR7 + 1∗ , C2. Oceanic Temperate. Brittany, Norway, N. Spain, Sweden, Faeroes. Distinct from W. controversa in the wider costa with elongate adaxial cells and from this and all other species of Weissia by the non-papillose adaxial cells. Some gatherings identified as W. controversa var. crispata are this plant. For information on W. perssonii see A. C. Crundwell, Trans. Brit. Bryol. Soc. 6,221–4, 1971.

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Fig. 80 1–4, Weissia rutilans: 1, stem and perichaetial leaves; 2, mid-leaf cells; 3, capsule (×20); 4; capsule mouth. 5–8, W. condensa: 5, stem and perichaetial leaves; 6, mid-leaf cells; 7, capsule (×20); 8, capsule mouth. 9–12, W. perssonii: 9, stem and perichaetial leaves; 10, adaxial side of costa at middle of leaf; 11, capsule (×20); 12, capsule mouth. Leaves ×40, cells ×420, capsule mouths ×40.

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¨ 3 W. rutilans (Hedw.) Lindb., Ofvers F¨orh. Kongl. Svenska Vetensk-Akad, 1863 (Fig. 80) W. mucronata Bruch & Schimp. Dull green or yellowish green patches, 3–10 mm high. Leaves incurved and crisped when dry, patent from erect basal part when moist, lower leaves oblonglanceolate, upper and perichaetial leaves oblong-lanceolate to narrowly lanceolate, acute; margins plane or slightly incurved above; costa stout, excurrent in mucro, adaxial cells ± quadrate in upper half of leaf; basal cells rectangular, hyaline, cells above ± quadrate, papillose, obscure, 8–10 μm wide in mid-leaf. Setae yellowish green, 8–10 mm long; capsules ovate-ellipsoid to ellipsoid, straight or slightly curved, smooth or striate when dry and empty, epiphragm lacking; peristome teeth rudimentary, to 80 μm long; spores 22–28 μm. Capsules common, autumn to spring. n = 13. On non-calcareous soil and on clay in turf, on woodland rides and banks, also on upland calcareous soil among rocks and in flushes. 0–450 m. Rare or occasional from Cornwall east to Kent and north to Orkney, W. Donegal, Down, Antrim, Londonderry. 72, H4, C. GB102 + 39∗ , IR1 + 3∗ , C1. European Temperate. Italy, Yugoslavia, C. and W. Europe, north to Scandinavia, Faeroes, Iceland, N. and E. Asia, N. and C. Africa, Canada, Australia. Distinguished in the field from the preceding and next two species in the relatively wider leaves with the margins only narrowly incurved above. According to Duell (1992), hardly distinct from W. squarrosa. However, the two are markedly distinct in capsule characters and W. squarrosa produces innovations from below the perichaetium.

Section 2 Hymenostomum (R. Brit.) Mull. ¨ Hal., Syn., 1849 Capsules emergent or exserted; peristome absent, epiphragm present; lid falling at maturity. ¨ 4 W. condensa (Voit) Lindb., Ofvers F¨orh. Kongl. Svenska Vetensk-Akad., 1863 (Fig. 80) ¨ ¨ ¨ Hymenostomum tortile (Schwagr.) Bruch & Schimp., W. tortilis (Schwagr.) Mull. Hal. Loose, readily disintegrating patches, green above, brownish below, mostly 5–15 mm high. Upper leaves crisped when dry, patent when moist, narrowly lanceolate, acute to obtuse and mucronate; margins plane below, involute above; costa stout, 80–100 μm wide near base, ending in apex or excurrent in mucro, adaxial cells ± quadrate in upper half of leaf; basal cells rectangular, hyaline, cells above ± quadrate, papillose, obscure, 8–9 μm wide in mid-leaf. Setae 2–4 mm long; capsules ellipsoid, symmetrical or slightly asymmetrical, mouth partially closed by fugacious epiphragm; peristome absent; spores 14–24 μm. Capsules frequent, spring. n = 13. On dry calcareous soil in turf, on stony banks, limestone terrain and among boulders. Lowland. Very rare, S. Devon, N. Somerset, Dorset, I. of Wight, S. Hampshire, Sussex, Kent, Surrey, E. Gloucester, Berwick. 12. GB13 + 5∗ .

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Submediterranean-Subatlantic. S., W. and C. Europe, Caucasus, Turkey, Cyprus, S. W. Asia, Canary Islands, N. Africa, Canada, Texas. This species is treated as vulnerable in the Red List of British Mosses.

¨ Ungarn, 1882 5 W. brachycarpa (Nees & Hornsch.) Jur., Laubm. Ost. ¨ Hal., Hymenostomum microstomum (Hedw.) R. Br., W. microstoma (Hedw.) Mull. W. ludwigii Crum Dark green tufts or patches, sometimes extensive, 7–10 mm high. Leaves strongly crisped when dry, patent when moist, narrowly lanceolate or from oblonglanceolate basal part narrowed to linear-lanceolate upper part, acute; margins plane below, involute above or plane throughout; costa excurrent, 35–50 μm wide near base, adaxial cells quadrate or elongate in upper half of leaf; basal cells rectangular, hyaline, cells above ± quadrate, papillose, obscure, 10–12 μm wide in mid-leaf. Setae yellowish, 1.5–7.0 mm long; capsules ovoid to ellipsoid, symmetrical, brown at maturity, contracted at mouth, epiphragm present but rupturing at maturity to release spores; exothecial cells not fragile; peristome lacking; spores 20–34 μm. Capsules common, winter, spring. Circumpolar Southern-temperate. Leaves narrowly lanceolate, basal part not wider than upper part margins plane var. brachycarpa Leaves linear-lanceolate from oblong-lanceolate basal part, margins involute above var. obliqua Var. brachycarpa ¨ Hal. W. microstoma var. brachycarpa (Nees & Hornsch.) Mull.

(Fig. 81)

Leaves narrowly lanceolate, not narrowed above basal part, margins plane throughout. Capsules ovoid to ellipsoid; spores 24–34 μm. On damp acidic soil in arable fields, on banks and woodland rides. Lowland. Rare in England, very rare in Scotland, extending north to Caithness, Fermanagh. 29, H1. GB44 + 6∗ , IR1. Europe, western N. America. Var. obliqua (Nees & Hornsch.) M. O. Hill, J. Bryol., 1981 ¨ Hal. var. microstoma W. microstoma (Hedw.) Mull.

(Fig. 81)

Leaves narrowly lanceolate from oblong-lanceolate basal part; margins plane below, involute above. Capsules ovate-ellipsoid or ellipsoid; spores 20–28 μm. n = 13∗ , 26. On banks and bare soil in turf in chalk and limestone grassland, occasionally on soil among rocks in lowland habitats and in ravines in montane habitats, calcicole. 0–420 m. Common in chalk and limestone areas in S. England, rare to occasional elsewhere, extending north to Shetland, rare in Ireland. 97,

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Fig. 81 1–5, Weissia brachycarpa var. obliqua: 1, stem and perichaetial leaves (×40); 2, mid-leaf cells (×420); 3, capsule; 4, capsule mouth (×40); 5, exothecial cells (×280). 6, W. brachycarpa var. brachycarpa: leaf (×40). 7–9, W. squarrosa: 7, leaf (×40); 8, capsule; 9, exothecial cells (×280). 10–13, W. rostellata: 10, plant (×10); 11, stem and perichaetial leaves (×20); 12, marginal cells at middle of leaf (×20); 13, capsule. 14–17, W. ×mittenii: 14, plant (×10); 15, stem and perichaetial leaves (×20); 16, mid-leaf cells (×420); 17, capsule. Capsules ×20.

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H17, C. GB346 + 84∗ , IR21 + 9∗ , C1 + 1∗ . Europe north to southern Scandinavia, Caucasus, Turkey, Cyprus, Asia, Azores, Algeria, Tunisia, N. America. Var. brachycarpa grows in moister habitats than var. obliqua and is not a calcicole, but the status of var. obliqua as a variety is questionable and it is not recognised by recent continental European authors.

¨ Hal., Syn. Musc. Frond., 1849 6 W. squarrosa (Nees & Hornsch.) Mull. Hymenostomum squarrosum Nees & Hornsch.

(Fig. 81)

Lax dull green patches, to c. 10 mm high, becoming decumbent at maturity of capsules and producing distant-leafed innovations from below perichaetia. Leaves somewhat crisped when dry, spreading to recurved when moist; margins of lower leaves plane, of upper leaves narrowly incurved above; costa excurrent, cells on adaxial side elongate in upper half of leaf; basal cells rectangular, hyaline, cells above ± quadrate, papillose, obscure, 10–12 μm wide in mid-leaf. Setae yellowish; capsules ellipsoid, dark greenish brown at maturity, epiphragm present, exothecial cells thin-walled, capsule walls rupturing at maturity to release spores; lids falling at maturity but epiphragm not rupturing; peristome absent; spores 22–28 μm. Capsules frequent, spring. Damp acid ground in fields, by ditches and ponds. Lowland. Rare and seen recently only in southern England but formerly extending north to Westmorland and Fife. 23. GB10 + 39∗ . Suboceanic Temperate. Rare in Europe, extending from Yugoslavia north to Scandinavia, Israel. Distinguished from W. brachycarpa by the frequently decumbent shoots with distant-leaved innovations and the thin-walled exothecial cells of the capsules rupturing to release the spores. The decrease in frequency of W. squarrosa may be due to changed agricultural practices. This species is considered endangered in the Red List of British mosses.

Section 3 Astomum (Hampe) Nyholm, Ill. Flora Nordic Mosses I, 1989 Capsules as long as or longer than setae, globose to ovoid, immersed or shortly exserted, usually cleistocarpous. For an account of the species of subgenus Astomum see A. C. Crundwell & E. Nyholm, J. Bryol. 7, 7–19, 1972.

¨ 7 W. rostellata (Brid.) Lindb., Ofvers F¨orh. Kongl. Svenska Vetensk-Akad., 1864 (Fig. 81) Astomum rostellatum (Brid.) Bruch & Schimp., Hymenostomum rostellatum (Brid.) Schimp. Ephemeral plants forming lax patches, c. 5 mm high. Leaves increasing in size up stems. Perichaetial leaves similar to upper stem leaves, crisped when dry, erectpatent when moist, 1.9–3.2 mm long, linear-lanceolate, acuminate; margins plane or occasionally narrowly incurved above, entire or in innermost perichaetial leaves

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minutely denticulate near base; costa excurrent to 75–150 μm, c. 50 μm wide near base, adaxial cells smooth, elongate; basal cells rectangular, hyaline, 30–70 μm long, cells above quadrate, pellucid, c. 10 μm wide in mid-leaf. Setae yellowishgreen, 0.7–1.5 mm long; capsules ovoid with oblique beak, cleistocarpous; spores (18−)22–27 μm. Capsules common, autumn. On moist gravel and mud by reservoirs, ditches and rivers, in hollows in grassland and on woodland rides. Lowland. Rare but widely distributed from N. Devon and E. Kent north to S. Northumberland and Midlothian, Anglesey, Leitrim, E. Mayo, Antrim, Cavan. 22, H4. GB31 + 9∗ , IR3 + 2∗ . European Temperate. Rare in Europe, extending north to S. Scandinavia, probably endemic to Europe. W. × mittenii (Bruch & Schimp.) Mitt. emend. A. J. E. Sm., J. Bryol. in press (Fig. 81) Astomum mittenii Bruch & Schimp., W. mittenii (Bruch & Schimp.) Mitt. Plants to 15 mm high. Lower leaves crisped when dry, spreading when moist, of ± uniform size up stems, only a few transitional to larger perichaetial leaves. Perichaetial leaves erect, 3–4 mm long, narrowly lanceolate; margins plane or occasionally very narrowly incurved above, entire; costa excurrent 50–140 μm, adaxial cells smooth, elongate; basal cells rectangular, hyaline, to 50 μm long cells above ± quadrate, pellucid, c. 10 μm wide in mid-leaf. Setae 1.0–1.7 mm long; capsules ± ovoid with long or short acute or blunt beak, but often malformed, cleistocarpous; spores very variable in size, (13−)18–20(−40) μm, often aborted. Capsules spring. On bare soil on clay banks, woodland rides and in arable fields. Lowland. Very rare, recorded from 5 localities in Sussex and Surrey but not seen since 1920. 3. GB5∗ . Endemic First found by William Mitten at two sites in Sussex in 1846 growing with W. multicapsularis, and was last found by W. E. Nicholson in 1920. The sporophyte resembles that of W. rostellata and the gametophyte that of W. multicapsularis, except that the adaxial cells of the costa are elongate. In view of the variable size of the spores and the capsules sometimes being malformed this plant is almost certainly of hybrid origin. It is possible that the gametophytes are derived from spores from the F1 hybrid between W. rostellata (from which the elongate adaxial cells of the costa may be derived) and W. multicapsularis (from which the habit of the plant is possibly derived). This would mean that the sporophytes of W. × mittenii are F2 hybrids. However, the situation is not clear as F1 hybrid capsules have never been found in mixed populations of the putative parents and W. × mittenii has only been found with W. multicapsularis.

8 W. multicapsularis (Sm.) Mitt., Ann. Mag. Nat. Hist., 1851 Astomum multicapsularis (Sm.) Bruch & Schimp.

(Fig. 82)

Plants ephemeral, forming lax dull green patches, to 15 mm high. Stems mostly unbranched. Leaves somewhat crisped when dry, stem leaves spreading when moist, of ± uniform size up stems except for a few transitional to the longer ± erect perichaetial leaves. Perichaetial leaves, 3.5–4.5 mm long, narrowly lanceolate;

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Fig. 82 1–5, Weissia multicapsularis: 1, plant; 2, stem and perichaetial leaves; 3, cells near base of perichaetial leaf; 4, marginal cells at middle of leaf; 5, capsule. 6–10, W. sterilis: 6, plant; 7, stem and perichaetial leaves; 8, marginal cells at middle of leaf; 9, cells near base of perichaetial leaf; 10, capsule. 11–15, W. levieri: 11, plant; 12, stem and perichaetial leaves; 13, marginal cells at middle of leaf; 14, cells near base of perichaetial leaf; 15, capsule. Plants ×10, leaves and capsules ×20, cells ×420.

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margins plane or occasionally very narrowly incurved above, ± entire; costa excurrent to 50–80 μm, c. 60 μm wide near base, adaxial cells in upper half of leaf papillose, quadrate; basal cells rectangular, hyaline, 40–120 μm long, cells above irregularly quadrate, papillose, pellucid, 9–10 μm wide in mid-leaf. Sporophytes rarely more than one per perichaetium; setae 0.5–0.8 mm long; capsules ovoid with ± conical beak, cleistocarpous, 0.70–0.85 mm long; spores 16–21 μm, finely papillose. Capsules occasional, spring. On damp acidic clay soil in turf, fields and on woodland rides. Lowland. Rare, Cornwall, S. Devon, Sussex, W. Kent, Oxford, Monmouth, Cheshire. 9. GB13 + 8∗ . Oceanic Temperate. France. Differs from other cleistocarpous Weissia species in the abrupt transition from short spreading stem leaves to long erect perichaetial leaves. It seems a curious misnaming that this plant, which usually only produces one sporophyte per perichaetium, should be called W. multicapsularis whilst W. sterilis usually produces more than one sporophyte per perichaetium. This species is considered endangered in the Red List of British mosses and is also listed as endangered in the Red Data Book of European Bryophytes.

9 W. sterilis W. E. Nicholson, J. Bot. Lond., 1903 ¨ Astomum crispum var. sterilis (W. E. Nicholson) Monk.

(Fig. 82)

Small groups or lax patches of plants, to 15 mm high. Stems often with clustered branches, each bearing two or more sporophytes per perichaetium. Leaves strongly crisped when dry, patent to spreading when moist, gradually increasing in size up stems with upper stem leave similar in length to perichaetial leaves. Perichaetial leaves 3.0–3.7 mm long, narrowly lanceolate; margins erect or narrowly incurved above, inner perichaetial leaves with a few small teeth near base; costa excurrent to 80–90 μm, 30–40 μm wide near base, adaxial cells smooth, quadrate; basal cells rectangular, hyaline, 30–70 μm long, cells above ± quadrate, papillose, pellucid, c. 10 μm wide in mid-leaf. Frequently 2 or more sporophytes per perichaetium; setae c. 4 mm long; capsules globose or ovoid with rostrate beak, cleistocarpous, c. 0.7 mm long; spores finely papillose, 18–20 μm. Capsules common, winter. On calcareous soil in south-facing chalk and limestone grassland. Lowland. Rare to occasional in southern England from S. Devon east to Kent, and north to Worcester and Cambridge, Montgomery. 19. GB26 + 13∗ . Oceanic Temperate. N. W. France. Distinct from the other cleistocarpous Weissia species in the clustered short branches at the tops of stems often with 2 or more capsules per perichaetium. It differs from W. longifolia in being taller with shorter perichaetial leaves with usually plane margins and from W. multicapsularis in the stem leaves grading in length to the perichaetial leaves.

10 W. levieri (Limpr.) Kindb., Eur. N. Amer. Bryin., 1897 Astomum levieri Limpr.

(Fig. 82)

Ephemeral plants forming compact dull green tufts, to 10 mm high; stems rarely branched. Leaves gradually increasing in size up stems, uppermost leaves not markedly distinct from perichaetial leaves. Perichaetial leaves strongly curled

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when dry, erect to erect-patent when moist, 3.0–4.5 mm long, 0.6–0.8 mm wide, narrowly lanceolate, acuminate; margins plane or occasionally slightly incurved above, often slightly denticulate near base of inner perichaetial leaves; costa excurrent to 130 μm, 50–80 μm wide near base, adaxial cells papillose, quadrate in upper part; basal cells rectangular, thin-walled, hyaline, 40–90 μm long, cells above quadrate, papillose, pellucid, c. 9 μm wide in mid-leaf. Usually only one sporophyte per perichaetium; setae 0.3–0.6 mm long; capsules ovoid, dehiscent, c. 0.7 × 0.9 mm long; beak 50–200 μm long; spores finely papillose, 18–22(−24) μm. Capsules common, late winter, early spring. In limestone grassland on soil and among rocks. Lowland. Very rare, W. Somerset, Glamorgan. 2. GB3. Mediterranean-Atlantic. Europe from Spain and Portugal east to Yugoslavia and north to France, Ukraine, Crimea, Algeria. Very similar in appearance to W. longifolia but readily distinguished by the capsules dehiscing in nature. For the occurrence of this plant in Britain see E. F. Warburg, Trans. Brit. Bryol. Soc. 3, 713–14, 1960. This species is considered endangered in the Red List of British mosses.

11 W. longifolia Mitt., Ann. Mag. Nat. Hist., 1851 Ephemeral plants in dull green, loose or compact patches, to 10 mm high. Leaves strongly curled when dry, erect-patent when moist. Perichaetial leaves 2.5– 6.0 mm long, narrowly lanceolate to linear-lanceolate; margins plane or incurved above; costa excurrent 30–100 μm, to 50(−80) μm wide near base, adaxial cells smooth and elongate or papillose and quadrate; basal cells irregularly rhomboidal, hyaline, cells above ± quadrate, papillose, opaque, 9–10 μm wide in mid-leaf. Setae 0.30–0.85 mm long; capsules ovoid, beaked, indehiscent in nature, 0.5– 1.2 mm long; spores coarsely papillose, 17–23 μm. Capsules common, winter, spring. Perichaetial leaves 3–6 mm long; margins plane or narrowly incurved above, capsules indehiscent, exothecial cells pale var. longifolia Perichaetial leaves 2.5–3.7 mm long; margins involute above, capsules dehiscing under pressure, exothecial cells yellowish var. angustifolia Var. longifolia (Fig. 83) W. crispa (Hedw.) Mitt., W. crispa var. aciculata (Hedw.) Dixon, Astomum crispum (Hedw.) Hampe Perichaetial leaves longer than stem leaves, conspicuous, 3–6 mm long, up to 0.9 mm wide, from broad ± colourless basal part linear-lanceolate, acuminate; margins plane or narrowly incurved above; margins of inner perichaetial leaves often denticulate near base; costa excurrent to 30 μm, adaxial cells quadrate or elongate; basal cells thin-walled, hyaline. Setae 0.3–0.6 mm long; capsules ovoid, indehiscent, 0.7–1.0 mm long, beak 80–140(−210) μm long; exothecial cells pale; calyptrae 0.5–0.7 mm long. n = 13, 13 + m. On non-calcareous loam and sandy soil in turf, on paths and in gardens. Lowland. Occasional to frequent in chalk

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Fig. 83 1–5, Weissia longifolia var. longifolia: 1, plant (×10); 2, stem and perichaetial leaves (×20); 3, cells near base of perichaetial leaf; 4, mid-leaf cells; 5, capsule (×29). 6–7, W. longifolia var. angustifolia: 6, perichaetial leaf (×20); 7, cells near base of perichaetial leaf. 8–11, Tortella inflexa: 8, plant (×10); 9, leaves (×40); 10, basal cells; 11, mid-leaf cells. Cells ×420.

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grassland north of London, very rare elsewhere, extending from Cornwall east to Kent and north to Durham and Berwick. 36. GB66 + 13∗ European Temperate. Europe north to Fennoscandia, Caucasus, Turkey, Asia, Canary Islands, N. Africa. Var. angustifolia (Baumgartner) Crundw. & Nyholm, J. Bryol., 1972 W. crispa auct. angl.

(Fig. 83)

Leaves increasing in size up stems so that perichaetial leaves are not noticeably larger than upper stem leaves. Perichaetial leaves 2.5–3.7 mm long, to 0.8 mm wide, expanded basal part of leaf yellowish; margins strongly incurved above, usually entire towards base in inner perichaetial leaves; costa excurrent to 50–100 μm, adaxial cells papillose, quadrate; basal cells incrassate, mostly yellowish. Setae 0.75–0.84 mm long; capsules indehiscent in nature but lid coming off under pressure on a slide; exothecial cells deep yellow; beak 200–350 μm long; calyptrae 0.75–1.20 mm long. On calcareous soil in chalk and limestone grassland, banks, paths and among limestone rocks. Occasional to frequent in chalk and limestone areas of southern and eastern England, rare elsewhere, extending north to S. Northumberland, rare in Ireland. 47, H7. GB119 + 53∗ , IR2 + 7∗ . European Temperate. Belgium, France, Portugal, Yugoslavia. The two varieties are distinct ecologically and in the incurvature of the perichaetial leaf margins, but intergrade to a considerable extent in Continental Europe. They differ from other cleistocarpous species of Weissia with short setae in their relatively small size, usually being less than 10 mm high.

43 TORTELLA LIMPR., LAUBM. DEUTSCHL., 1888 Dioicous. Stems usually without central strand, weak sclerodermis and hyalodermis present. Leaves crisped and curled when dry, erect to recurved when moist, usually fragile, lanceolate to linear-lanceolate, acute to obtuse and mucronate; margins plane or incurved above; costa ending in apex or excurrent, in section with two stereid bands, adaxial side 2–6(−10) cells wide, cells quadrate to elongate; basal cells hyaline and often ascending up margins, transition to chlorophyllous cells usually abrupt, upper cells hexagonal, papillose, opaque or pellucid. Perichaetial leaves ± similar to stem leaves. Capsules erect, ellipsoid or cylindrical, straight or slightly curved, peristome teeth filiform, usually spirally coiled; calyptrae cucullate. A ± world-wide genus of about 50 mainly calcicole species. Derivation: diminutive of twisted, referring to the twisted peristomes.

1 Leaves straight or curved but not twisted or crisped when dry, cells in upper part of leaf 6–8 μm wide, 2–3-stratose forming with costa long trigonous very fragile setaceous acumen 3. T. fragilis Leaves usually crisped, strongly twisted, curled or incurved when dry, cells unistratose throughout, apex various but never setaceous 2

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2 Leaves tightly incurved and imbricate with costae conspicuous and glossy when dry, upper part nearly always lost 4. T. nitida Leaves not tightly incurved nor costae conspicuously glossy when dry, most leaves usually intact 3 3 Lamina cells continuous over adaxial side of costa at least in middle part of leaves 4 Lamina cells not continuous over adaxial side of costa 6 4 Leaves strongly curled and crisped when dry, flexuose and undulate when moist, longly tapering to acuminate apex 1. T. tortuosa Leaves not as above 5 5 Costa excurrent, transition from basal to upper chlorophyllous cells abrupt, plants on soil or sand 8. T. flavovirens Costa ending in or below apex, transition from basal to chlorophyllous cells not abrupt, plants saxicolous 5. T. inflexa 6 Leaves gradually tapering to acuminate apex 2. T. densa Leaves shortly or abruptly tapered to acute or subobtuse apex 7 7 Leaves patent to spreading when moist, upper cells strongly papillose, opaque, 8–10 μm wide 6. T. inclinata Leaves reflexed from ± erect base when moist, upper cells obscurely papillose, ± pellucid, 8–12 μm wide 7. T. limosella 1 T. tortuosa (Hedw.) Limpr., Laubm. Deutschl., 1888 Trichostomum tortuosum (Hedw.) Dixon

(Fig. 84)

Yellowish to green, sometimes large cushions, tufts or patches, 1–8 cm high. Leaves strongly curled and contorted when dry, spreading, flexuose when moist, linear, gradually tapering from hyaline basal part to long acuminate apex, rarely narrowly lanceolate and more abruptly tapering, lamina sometimes torn or broken; margins plane, undulate, papillose-crenulate, denticulate or not near apex; costa excurrent, adaxial cells in middle part of leaf quadrate-hexagonal; basal cells narrowly rectangular to linear, hyaline, extending up margins, transition to chlorophyllous cells abrupt, cells above quadrate-hexagonal, papillose, unistratose throughout, 8–10 μm wide in upper part of leaf. Setae yellowish red; capsules cylindrical, straight to curved; peristome teeth long, filiform, spirally curved; spores 20–26 μm. Capsules rare, summer. n = 13. On rocks, in rock crevices, soil in turf, in flushes, where the substrate has at least some trace of base. 0–1200 m. Rare in lowland England, frequent or common elsewhere, common in western Ireland, occasional elsewhere. 100, H37, C. GB798 + 75∗ , IR27 + 8∗ , C1. Circumpolar Boreo-temperate. Europe north to Svalbard, Turkey, Cyprus, Caucasus, N. and E. Asia, Madeira, Canary Islands, Algeria, Morocco, N. America, Greenland, Peru, Tierra del Fuego. The linear, longly tapering leaves, curled and contorted when dry, usually readily distinguish T. tortuosa from other species. Short-leaved forms may be confused with T. densa, T. inclinata or T. flavovirens. The two latter have the leaves less contorted when dry and in the

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Fig. 84 1–4, Tortella tortuosa: 1, leaves; 2, leaf base (×40); 3, adaxial side of costa at middle of leaf; 4, capsule (×15). 5–7, T. nitida: 5, 6, young and old leaves; 7, mid-leaf cells. 8–11, Tortella fragilis: 8, very young leaf; 9, older broken leaf; 10, leaf base (×30); 11, mid-leaf cells. Leaves ×15, cells ×420.

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former they are scarcely undulate when moist. In T. densa and T. inclinata the cells on the adaxial side of the costa are elongate. In the short-leaved forms of T. tortuosa, which occur particularly in Ireland and have also been mistaken for T. fragilis, the cells of the lamina are only partially continuous over the adaxial side of the costa. Such plants may be worthy of varietal recognition. T. fragilis differs in the 2–3-stratose and fragile upper part of the leaf.

2 T. densa (Lorentz & Molendo) Crundw. & Nyholm, Trans. Brit. Bryol. Soc., 1962 (Fig. 85) T. tortuosa fo curta Albertson Dull green patches or tufts, to 4 cm high; stems not tomentose. Lower leaves straight or slightly curved, upper ± erect and curled when dry, erect-patent, hardly flexuose when moist, narrowly lanceolate to linear-lanceolate, gradually tapering to acuminate apex; margins papillose-crenulate, hardly undulate; costa ending in apex or shortly excurrent, adaxial cells elongate; basal cells narrowly rectangular to linear, hyaline, ascending up margins, transition to chlorophyllous cells abrupt, cells above hexagonal, papillose, opaque, cells in upper part of leaf 7–10 μm wide. Sporophytes unknown. n = 14. On exposed shallow soil, in limestone crevices and grassy flushes, strongly calcicole. 0–580 m. Occasional in the Pennines, very rare elsewhere, from E. Gloucester and Caernarfon north to Skye and W. Sutherland, Clare, Mayo, Sligo, Fermanagh. 12, H5. GB16 + 3∗ , IR4. Suboceanic Temperate. Central and western Europe north to Norway, Turkey, Caucasus. 3 T. fragilis (Hook. & Wilson) Limpr., Laubm. Deutschl., 1888 ¨ Hal. Trichostomum fragile (Hook. & Wilson) Mull.

(Fig. 84)

Yellowish green to green patches, 0.5–2.5 cm high. Leaves rigid, lower ± straight, upper curved when dry, erect-patent, not or scarcely flexuose or undulate when moist, narrowly linear-lanceolate, tapering from hyaline basal part to long setaceous apex, usually broken off except in young leaves; margins plane or inflexed above, papillose-crenulate; costa glossy on abaxial side when dry, extending to apex and forming with 2–3-stratose upper lamina cells a long fragile setaceous apex, cells on adaxial side hexagonal; basal cells linear, hyaline, extending up margins, transition to chlorophyllous cells abrupt, cells above ± hexagonal, papillose, opaque, 6–10 μm wide, in upper part of leaf 2–3-stratose and hardly distinguishable from costa, 6–10 μm wide. Sporophytes unknown in the British Isles. On basic montane rock ledges and in calcareous dune-slacks. 0–1060 m. Very rare, Fife, Mid Perth, Angus, Banff, Sutherland, Caithness, Fermanagh. 7, H1. GB7 + 2∗ , IR1. Circumpolar Boreo-arctic Montane. The Netherlands and montane and northern Europe north to Svalbard, Faeroes, Iceland, Turkey, Caucasus, Asia, Tenerife, Sahara, South Africa, N. America, Tierra del Fuego, Antarctica, New Zealand, Hawaii. The fragile leaf apices appear to provide a means of vegetative propagation. When dry the rigid and curved rather than strongly crisped or incurved leaves will distinguish this plant

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Fig. 85 1–4, Tortella flavovirens: 1, leaves (×25): 2, capsule (×10); 3, adaxial side of costa at middle of leaf: 4, 5, mid-leaf cells. 6–7, T. inclinata: 6, leaf (×25); 7, adaxial side of costa at middle of leaf. 8–9, T. densa: 8, leaf (×25); 9, adaxial side of costa at middle of leaf. 10–12, T. limosella: 10, leaves (×40); 11, mid-leaf cells; 12, adaxial side of costa at middle of leaf. Cells ×420.

43 Tortella

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from T. tortuosa, some forms of which may have fragile leaf apices and with which it has been confused. The setaceous leaf apices if present are also distinctive.

4 T. nitida (Lindb.) Broth., Nat. Pflanzenfam., 1902 Trichostomum nitidum (Lindb.) Schimp.

(Fig. 84)

Light green to yellowish green tufts, 0.5–1.0 cm high. Leaves tightly incurved when dry, erect-patent to spreading, slightly undulate when moist, very fragile, upper part of leaf usually missing, linear-lanceolate, acute to acuminate; margins plane, papillose-crenulate; costa excurrent in short mucro, whitish and shining on abaxial side when dry, adaxial cells quadrate; basal cells rectangular, ascending up margins, transition to chlorophyllous cells not very abrupt, cells above quadrate to hexagonal, papillose, opaque, 6–10 μm wide in upper part of leaf. Sporophytes unknown in the British Isles. On exposed basic rocks and wall tops, especially limestone. Lowland. Occasional in S. W. England and Wales, very rare elsewhere, W. Sussex, Hereford, north to Derby, Stirling and Rum, occasional in W. Ireland, Jersey. 40, H15, C. GB124 + 40∗ , IR36 + 5∗ , C1. Mediterranean-Atlantic. Europe north to the British Isles, Turkey, Cyprus, Macaronesia, N. Africa. Recognisable when dry by the neat rounded tufts and the tightly incurved fragile leaves with conspicuous glossy costae. Has been confused with T. tortuosa and T. flavovirens but differs from these in the characters just mentioned and in the leaves having the transition from the hyaline basal cells to chlorophyllous cells not as abrupt.

5 T. inflexa (Bruch) Broth., Nat. Pflanzenfam., 1902 (Fig. 83) Small bright green patches, 2–6 mm high. Leaves strongly curled when dry, erect to spreading when moist, linear-lanceolate to linear, apex ± acute, often subcucullate; margins often inflexed at least above, papillose-crenulate; costa ending below apex, adaxial cells quadrate-hexagonal at middle of leaf; basal cells narrowly rectangular, hyaline, ascending up margins, transition to chlorophyllous cells gradual, cells above quadrate-hexagonal, papillose, opaque, cells in upper part of leaf 8–10 μm wide. Setae 5 mm long; capsules narrowly ellipsoid, only seen once in England. On chalk or oolitic limestone stones in grassland, on banks and in woodland. Lowland. Rare to occasional from Dorset east to Kent and north to Hereford and Bedford, S. E. Yorkshire. 21. GB68. Mediterranean-Atlantic. France, Portugal, Sardinia, Minorca, Malta, Crete, Israel, N. Africa. Although not recognised in Britain until 1957 this species is probably native but is apparently spreading in southern England. As fertile material with immature capsules has only been found once in England it probably spreads by vegetative means, pairs of deciduous leaves falling away from the stem apex. For an account of this plant in Britain see E. C. Wallace, J. Bryol. 7, 153–6, 1972.

6 T. inclinata (R. Hedw.) Limpr., Laubm. Deutschl., 1888 Trichostomum inclinatum (R. Hedw.) Dixon

(Fig. 85)

Yellowish green patches, c. 1 cm high; stems without central strand, tomentose below. Leaves curled inwards, not or scarcely crisped when dry, patent to spreading,

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slightly undulate when moist, linear-lanceolate, shortly or abruptly tapering to slightly cucullate acute or subobtuse apex; margins plane, papillose-crenulate; costa excurrent, adaxial cells elongate; basal cells narrowly rectangular to linear, hyaline, extending up margins, transition to chlorophyllous cells abrupt, cells above rounded-hexagonal, papillose, opaque, 8–10 μm wide in upper part of leaf. Small terminal propaguliferous shoots sometimes present. Capsules ellipsoid, straight or slightly curved; peristome teeth filiform, spirally coiled, fugacious; spores 10–16 μm. n = 7. Capsules very rare, summer. On shallow soil on limestone, chalk banks and calcareous sand-dunes. 0–500 m. Rare, widely distributed from Surrey, N. Norfolk and E. Gloucester north to Caithness, W. Mayo, Down. 26, H2. GB26 + 7∗ , IR3. Circumpolar Temperate. Europe north to Fennoscandia, Turkey, Caucasus, N. Asia, Azores, Algeria, southern Africa, N. America, Australia. 7 T. limosella (Stirt.) P. W. Richards & E. C. Wallace, Trans. Brit. Bryol. Soc., 1950 (Fig. 85) T. flavovirens ssp. limosella (Stirt.) Podp., Trichostomum limosellum (Stirt.) Dixon Dense patches, 4–8 mm high. Upper leaves longer than lower, loosely curled, hardly crisped when dry, reflexed from erect basal part when moist, lanceolatelingulate, acute to subobtuse and apiculate; margins plane, crenulate-serrulate with scattered irregular poorly defined teeth; costa excurrent, adaxial cells at middle of leaf elongate; basal cells hyaline, ascending up margins, sharply differentiated from chlorophyllous cells, cells above thick-walled, quadrate-hexagonal, weakly papillose, hardly opaque, 8–12 μm wide in upper part of leaf. Gametangia and sporophytes unknown. Seashore west of Arisaig, W. Inverness, 1906, not seen since. 1. GB1∗ . Endemic (Oceanic Boreo-temperate). Dixon & Jameson (1924) suggest this plant is closely related to T. flavovirens but the elongate adaxial cells of the costa indicate that its relationship is with T. inclinata, but it differs from that species in the reflexed leaves and larger obscurely papillose cells. The precise status of T. limosella is obscure, but having examined the type specimen there are no grounds for regarding it as a subspecies or variety of any other Tortella species. Listed as extinct in both the Red List of British mosses and the Red Data Book of European Bryophytes.

8 T. flavovirens (Bruch) Broth., Nat. Pflanzenfam., 1902 (Fig. 85) T. flavovirens var. glareicola (A. Chr.) Crundw, & Nyholm, Trichostomum flavovirens Bruch Yellowish green to brownish green tufts or patches, to 1.5 cm high; stems often with central strand, not tomentose below. Leaves crisped when dry, lower small, erect-patent, upper larger, spreading when moist, narrowly lanceolate to linear-lanceolate, shortly or abruptly tapering to acute or subobtuse, mucronate, frequently cucullate apex; margins plane below, usually erect or incurved above, papillose-crenulate; costa excurrent, adaxial cells in middle part of leaf hexagonal;

44 Trichostomum

285

basal cells narrowly rectangular to linear, hyaline, ascending up margins, transition to chlorophyllous cells abrupt, upper cells hexagonal, papillose, hardly opaque, 8–14 μm wide in mid-leaf. Setae purplish-red; capsules narrowly ellipsoid; peristome teeth filiform, straight, fugacious; spores 12–14 μm. Capsules very rare. In calcareous dune-slacks, on sandy soil, on banks and in rock crevices, almost exclusively in maritime situations, sometimes within the spray zone. Lowland. Rare along the east and north coasts, frequent or common along the south and west coasts. 61, H17, C. GB221 + 26∗ , IR26 + 3∗ . Submediterranean-Subatlantic. Mediterranean and Atlantic coasts of Europe, Turkey, Cyprus, China, Japan, Macaronesia, N. Africa, western N. America. Var. glareicola, a plant with leaf cells 10–14 μm wide, distinguished from the type with cells 8–10 μm wide, has been recognised in Britain. However, in Cornwall the two varieties intergrade completely (Dr D. T. Holyoak, pers. commun.) so I have not maintained the variety. T. flavovirens occurs in a variety of coastal habitats but never inland, whereas T. inclinata, which also occurs inland, is only found on calcareous sand-dunes when near the coast. The two species cannot be separated in the field but the shape of the cells on the adaxial side of the costa will readily separate the two microscopically.

¨ 44 TRICHOSTOMUM BRUCH IN F. MULL., FLORA, 1829 Usually dioicous. Plants forming tufts or patches. Stems with or without central strand. Leaves linear-lanceolate to lanceolate or lingulate, acute or obtuse; margins plane or recurved, papillose-crenulate; costa ending below apex or excurrent, adaxial cells quadrate, in section with two stereid bands; basal cells ± rectangular, hyaline or yellowish, cells above ± hexagonal, papillose, opaque. Setae long; capsules erect, ellipsoid or cylindrical; lid rostrate; peristome teeth short, straight or spirally coiled, divided, perforated or entire; calyptrae cucullate. Laminal KOH reaction yellowish orange to orange. A ± world-wide genus of 130 species. Derivation: meaning hair + mouth, referring to the peristome teeth. The genus Trichostomum even as recognised by Zander (1993) is a heterogeneous collection of species. The situation is improved somewhat if the two species, T. recurvifolium and T. caespitosum, placed in Trichostomum by Zander (1993) are moved to Paraleptodontium and Pottiopsis respectively.

1 Leaf apices usually cucullate 2. T. crispulum Leaf apices plane 2 2 Costa excurrent in stout mucro 1. T. brachydontium Costa ending below apex or if slightly excurrent then not forming a mucro 3 3 Basal part of leaf hardly expanded; margins often sinuose or toothed above, mid-leaf cells ± quadrate 3. T. tenuirostre Leaf bases expanded; margins not sinuose or toothed, mid-leaf cells often shortly rectangular 4. T. hibernicum

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Fig. 86 1–4: Trichostomum brachydontium: 1, leaves; 2, leaf apex (×100); 3, mid-leaf cells; 4, capsule. 5–8, T. crispulum: 5, leaves; 6, leaf apex (×100); 7, mid-leaf cells; 8, capsule. Leaves ×25, cells ×420, capsules ×15.

¨ 1 T. brachydontium Bruch in F. Mull., Flora, 1829 T. mutabile Bruch

(Fig. 86)

Yellowish green to dark green patches or tufts, sometimes reddish below, (0.5−)1.0–4.0 cm high. Leaves crisped and incurved when dry, patent to recurved

44 Trichostomum

287

when moist, lingulate to narrowly lingulate-lanceolate or linear-lanceolate, obtuse to acute, rarely acuminate; margins plane or narrowly recurved, finely crenulate above, sometimes denticulate near base; costa strong, usually excurrent in stout mucro, rarely in a cuspidate point; basal cells irregularly rectangular to narrowly rectangular, hyaline or yellowish, cells above irregularly hexagonal, papillose, opaque, 6–8 μm wide in mid-leaf. Setae yellow; capsules ellipsoid to narrowly ellipsoid; peristome teeth short, very fragile; spores 14–18 μm. Capsules rare, spring. In basic or acidic habitats by the coast, in basic habitats elsewhere, on soil in turf, on banks, cliffs, sand-dunes, in rock and wall crevices, in shaded or exposed situations. 0–700 m. Rare in lowland England and eastern Scotland, frequent or common elsewhere, common in western Ireland. 96, H27, C. GB777 + 65∗ , IR115 + 13∗ , C10 + 1∗ . Submediterranean-Subatlantic. Europe north to Scandinavia, Faeroes, Iceland, Turkey, Cyprus, Caucasus, Siberia, China, Japan, Bali, Macaronesia, Africa, C. and S. America, Juan Fernandez, New Zealand. A very variable species for which two varieties have been recorded from the British Isles, var. littorale (Mitt.) C. E. O. Jensen and var. cophocarpum (Schimp.) P. Cout., but both intergrade with the type to such an extent that they cannot be maintained. Whilst T. brachydontium tends to have a western distribution in the British isles it is sometimes the only moss species found in very dry sites in soil and rock crevices in the Mediterranean region and Macaronesia.

¨ 2 T. crispulum Bruch in F. Mull., Flora, 1829 (Fig. 86) Dense yellowish green to dark green tufts or patches, sometimes blackish below, 0.5–4.0(−8.0) cm high. Leaves crisped when dry, erect-patent to patent or slightly recurved when moist, lingulate to lanceolate or narrowly lanceolate, tapering to acute to obtuse, apiculate, usually cucullate apex; margins in upper part usually erect or incurved, finely crenulate above; costa ending below apex to excurrent; hyaline basal cells variable in extent up leaf, narrowly rectangular and incrassate towards costa, shorter, wider and thinner-walled towards margins, cells above quadrate-hexagonal, papillose, opaque, 6–8(−10) μm wide in mid-leaf. Setae reddish; capsules narrowly cylindrical; spores 16–18 μm. Capsules rare or occasional, spring. n = 12, 13. In shady or exposed basic habitats, on soil, rocks, rocky banks, cliff ledges, mortar of old walls, sand-dunes and in chalk grassland. 0–1175 m. Generally distributed, frequent or common in basic areas, rare elsewhere, extending north to Shetland. 101, H39, C. GB601 + 53∗ , IR121 + 10∗ , C1 + 2∗ . Circumpolar Southern-temperate. Europe north to Svalbard, Turkey, Cyprus, Caucasus, Asia Minor, Siberia, E. Asia, New Guinea, Macaronesia, N. and C. Africa, Newfoundland, New Mexico. An exceedingly variable species usually easily recognised by the cucullate leaf apices. Four varieties of T. crispulum have been recognised in the British isles: var. brevifolium (Schimp.) ¨ Hal.) Bruch & Schimp., var. elatum Schimp., var. nigroviride (Braithw.) Dixon and var. Mull. viridulum (Bruch) Dixon. These varieties are based on habit, colour, leaf shape and size, form of leaf apex and cell size – all of which may be environmentally influenced. They are of

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doubtful status and not recognised here as equally distinctive but undescribed plants occur and some of the distinctive varietal characters may be found in otherwise typical plants. It seems likely that the plants are subject to environment and genetic variation not amenable to taxonomic treatment. Forms with plane apices may be separated from T. tenuirostre by the margins not undulate or sinuose. T. brachydontium usually has wider leaves with more longly excurrent costa.

¨ 3 T. tenuirostre (Hook. & Taylor) Lindb., Ofvers F¨orh. Kongl. Svenska Vetensk-Akad., 1884 ¨ Hal. Oxystegus tenuirostis (Hook. & Taylor) A. J. E. Sm., T. cylindricum (Brid.) Mull. Lax tufts or patches, to 7 cm high. Leaves distant or crowded, often varying in size along stems, loosely incurved or curled when dry, erect-patent to spreading, sometimes secund, often undulate when moist, 3–7 mm long, from ± erect but not expanded basal part linear-lanceolate, apex acute to subobtuse; margins plane, finely crenulate, often sinuose, notched or obscurely toothed above or with 2–3 teeth near apex; costa ending below apex to slightly excurrent; cells in basal part inflated, thin-walled, hyaline, irregularly rectangular, cells above quadrate, papillose or not, opaque, 7–10 μm wide in mid-leaf, 1–2 marginal rows sometimes more incrassate and distinct. Setae yellowish, flexuose; capsules cylindrical; peristome teeth short, straight, porose; spores 16–18 μm. Capsules very rare, late spring, early summer. Leaves not crowded, spreading, mid-leaf cells 8–10 μm wide Leaves crowded, erect-patent, mid-leaf cells 7–8 μm wide

var. tenuirostre var. holtii

Var. tenuirostre (Fig. 87) Plants yellowish green above, darker or blackish below. Leaves not crowded, spreading, linear-lanceolate; cells papillose, 8–10 μm wide in mid-leaf. On usually acidic rocks and in rock crevices by streams, springs, waterfalls, upland pools and lakes, rarely on tree trunks, in woodland at low altitudes, in sheltered or exposed habitats at higher altitudes. 0–610 m. Frequent or common in the west from Cornwall to W. Sutherland, rare elsewhere, rare to occasional in Ireland. 66, H21. GB408 + 34∗ , IR71 + 7∗ . Circumpolar Boreo-temperate. Europe north to Fennoscandia, Turkey, Caucasus, Algeria, Morocco. Var. holtii (Braithw.) Dixon, Stud. Handb. Br. Mosses, 1896 (Fig. 87) Plants greenish. Leaves crowded, ± erect-patent, linear-lanceolate; cells somewhat papillose to almost smooth, 7–8 μm wide in mid-leaf. On damp shaded rocks. Rare, western Britain from N. W. Wales, Derby and Westmorland north to Argyll and Skye, old records from Kerry. 13, H2. Germany, Norway. The status of var. holtii is open to question as the characters attributed to it may occur independently in the type. T. tenuirostre has sometimes been confused with T. hibernicum but the latter is distinct in the leaves not or scarcely undulate, sharply reflexed from an expanded base, the margins not notched or toothed and the cells often shortly rectangular.

44 Trichostomum

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Fig. 87 1–4, Trichostomum tenuirostre var. tenuirostre: 1, leaf (×15); 2, leaf base (×70); 3, leaf apex (×70); 4, mid-leaf cells (×420). 5, T. tenuirostre var. holtii: mid-leaf cells (×420). 6–9, T. hibernicum: 6, leaves (×15); 7, leaf base (×70); 8, leaf apex (×100); 9, mid-leaf cells (×420). 10–14, Pottiopsis caespitosa: 10, plant (×10); 11, perichaetial bract (×40); 12, stem leaf (×40); 13, cells from upper part of leaf (×430); 14, capsule mouth (×450).

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R. H. Zander (Lindbergia 4, 285–8, 1978) describes as var. gemmiparum (Schimp.) R. H. Zander a form of this species with gemmae borne on rhizoids arising from the adaxial surface of the leaves. The gemmae are red-brown to brown, clavate, simple or branched, multicellular and 150–250(−800) × 70–90(−140) μm. The plant, which is rare, is reported from montane habitats in E. France, Switzerland and elsewhere in the Northern Hemisphere and could possibly occur in the British isles.

4 T. hibernicum (Mitt.) Dixon, Stud. Handb. Br. Mosses, 1896 Oxystegus hibernicus (Mitt.) Hilp.

(Fig. 87)

Yellowish green tufts or scattered plants, 1–10 cm high. Leaves not crowded, crisped and incurved when dry, spreading, flexuose, usually not undulate when moist, from expanded basal part narrowly linear-lanceolate, tapering to acute apex; margins plane, finely crenulate, not notched or toothed; costa ending in apex or slightly excurrent; cells in basal part inflated, irregularly rectangular, hyaline, cells above shortly rectangular to irregularly quadrate, papillose, 8–10 μm wide in mid-leaf. Capsules cylindrical, very rare. Among rocks and in crevices by streams and waterfalls, on damp sheltered cliff ledges. 0–800 m. Rare in western Scotland from Arran north to Ross, Skye the Outer Hebrides and W. Sutherland, Kerry, E. Cork, W. Galway, W. Mayo, W. Donegal. 16, H6. GB34 + 6∗ , IR14 + 6∗ . Hyperoceanic Temperate. Doubtfully recorded from Czechoslovakia and Turkey. Distinctive in the expanded leaf bases, the margins not sinuose or toothed, and the midleaf cells often shortly rectangular.

45 POTTIOPSIS BLOCKEEL & A. J. E. SM., J. BRYOL., 1998 A monotypic genus with the characters of the species. Derivation: meaning with the appearance of a Pottia.

1 P. caespitosa (Bruch ex Brid.) Blockeel & A. J. E. Sm., J. Bryol., 1998 (Fig. 87) ¨ Hal., Trichostomum caespitosum (Bruch ex Pottia caespitosa (Bruch ex Brid.) Mull. Brid.) Jur. Autoicous. Gregarious or scattered ephemeral plants. Stems with central strand. Leaves broadly lanceolate, 2–3 times as long as wide, acute; margins plane, entire; costa excurrent 25–75 μm, adaxially 2 cells wide, cells quadrate, in section with well developed abaxial stereid band, poorly developed adaxial band; cells irregularly rounded-quadrate, verrucose, 7–11 μm wide in upper part of leaf. Perichaetial leaves distinctly broader than stem leaves, sheathing, concave. Setae yellow, 1.7–3.0 mm long; capsules ovoid, 0.9–1.0 × 0.55–0.70 mm with one row of thick-walled cells at the constricted mouth; lid rostrate; annulus present; peristome teeth 25–110 μm long, imperfect, usually cleft; calyptrae smooth, cucullate;

46 Pleurochaete

291

spores minutely papillose, 15–19 μm. Capsules common, December to April. Laminal KOH reaction yellow to orange. On patches of soil in chalk grassland, on sand-dunes and limestone banks. Lowland. Rare in southern England, extending north to Hereford and Cambridge. 17. GB19 + 10∗ . European Temperate. C. and S. Europe. The above description is an augmentation of that of Pottia caespitosa prepared by Dr D. F. Chamberlain in the first edition of this book, but for reasons given below this species is now placed in its own genus. It differs from Pottia and species of Tortula section Pottia in the larger sheathing perichaetial leaves, smaller spores and incrassate leaf cells. It differs from both in the perichaetial leaves being larger than the stem leaves. It differs from Trichostomum in its ephemeral habit, in being autoicous and in producing abundant capsules.

¨ ¨ 46 PLEUROCHAETE LINDB., OFVERS FORH. KONGL. SVENSKA VETENSK-AKAD., 1864 Dioicous. Stems with small central strand. Leaves crisped when dry, squarrose from erect sheathing basal portion when moist, acute; margins toothed above; costa percurrent or excurrent; basal cells rectangular, coloured except for marginal band of hyaline cells, cells above hexagonal, papillose. Perichaetia on very short lateral branches. Setae lateral, long; capsules erect, cylindrical, curved; peristome with basal membrane, 32 filiform papillose slightly twisted teeth; calyptrae cucullate. Laminal KOH colour reaction deep yellow to orange. A small genus of 4 species distributed through Europe, Asia, N. and C. Africa, America. Derivation: meaning side hair, from the lateral position of the setae.

¨ 1 P. squarrosa (Brid.) Lindb., Ofvers F¨orh. Kongl. Svenska Vetensk-Akad., 1864 (Fig. 88) Lax yellowish green tufts, 1–7 cm high. Upper leaves crisped when dry, squarrose from ± erect sheathing base when moist, lanceolate to linear-lanceolate, acuminate; margins plane, denticulate below, crenulate and irregularly toothed above; costa percurrent or very shortly excurrent; smooth on abaxial side; basal cells rectangular or narrowly rectangular, incrassate, coloured, 3–4 marginal rows hyaline, with thinner walls, ascending up margins and forming hyaline band in lower part of leaf, upper cells ± quadrate, papillose, opaque, 8–10 μm wide in mid-leaf. Capsules unknown in the British Isles. On dry ground on sand-dunes, in chalk and limestone grassland and on cliff tops, especially near the sea. 0–300 m. Occasional but sometimes locally abundant in coastal areas, from Cornwall north to Westmorland and east to E. Kent, rare inland, Clare, Wicklow, Dublin, Meath. 34, H4, C. GB73 + 33∗ , IR4 + 2∗ , C7 + 2∗ . Submediterranean-Subatlantic. S. and W. Europe north to Gotland, Turkey, Cyprus, Caucasus, Iran, Himalayas, China, Macaronesia, N. Africa, Kenya, Arizona, C. America.

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47 PARALEPTODONTIUM D. G. LONG, J. BRYOL., 1982 A monotypic genus with the characters of the species. Derivation: meaning close to Leptodontium.

1 P. recurvifolium (Taylor) D. G. Long, J. Bryol., 1982 (Fig. 88) Bryoerythrophyllum recurvifolium (Taylor) R. H. Zander, Leptodontium recurvifolium (Taylor) Lindb., Trichostomum recurvifolium (Taylor) R. H. Zander Lax green or yellowish green tufts, 3–10 cm high; stems without central strand. Leaves strongly crisped when dry, patent to squarrose from erect base, ± undulate when moist, fragile, ovate to lanceolate, apex acute to obtuse and apiculate; margins plane, coarsely serrate above, serrulate below; costa ending in apex to shortly excurrent, with large papillae and isodiametric cells on adaxial side; basal cells rectangular to shortly rectangular, cells above quadrate to hexagonal, papillose, opaque, thin-walled to incrassate, 12–16 μm wide in mid-leaf, 1–2 marginal rows elongate, more incrassate, smooth, pellucid, forming narrow border. Only female plants known. On damp base-rich cliffs, rock ledges, banks and rock crevices, often near waterfalls. 100–720 m. Rare in Merioneth, Caernarfon, Westmorland, Cumberland, occasional in the western Scottish Highlands from Stirling to Sutherland, Outer Hebrides, Kerry, W. Cork. W. Galway, W. Mayo, W. Donegal. 17, H6. GB37 + 7∗ , IR11 + 3∗ . Oceanic Boreal-montane. Nepal, British Columbia, Alaska. Variously placed in Leptodontium, Bryoerythrophyllum or Trichostomum. D. G. Long (J. Bryol. 12, 179–84, 1982) presents excellent grounds for placing this species in a genus of its own.

Subfamily 2 MERCEYOIDEAE Stem sclerodermis usually differentiated from central cylinder. Leaves lanceolate, frequently with differentiated basal part; costa mostly with two stereid bands, adaxial side often grooved, mostly 2(−4) cells wide. Clavate gemmae sometimes present.

Tribe 1 Bryoerythrophylleae Plants often large. Leaf margins recurved or revolute, sometimes denticulate or dentate above, costa 2(−4) cells wide on adaxial side, in section with two stereid bands, abaxial band often reniform.

48 DIALYTRICHIA (SCHIMP.) LIMPR., LAUBM. DEUTSCHL., 1888 A monotypic genus with the characters of the species. Derivation: meaning separate hairs, referring to the peristome teeth.

48 Dialytrichia

293

Fig. 88 1–4, Dialytrichia mucronata: 1, leaves (×15); 2, mid-leaf cells; 3, section through margin at middle of leaf; 4, sporophyte (×7). 5–7, Pleurochaete squarrosa: 5, leaves (×17.5); 6, marginal cells at middle of leaf; 7, marginal cells towards leaf base. 8–9, Paraleptodontium recurvifolium: 8, leaves (×30); 9, marginal cells in upper part of leaf. Cells ×420.

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1 D. mucronata (Brid.) Broth., Nat. Pflanzenfam., 1902 Cinclidotus mucronatus (Brid.) Molendo, C. brebissonii (Brid.) Husnot

(Fig. 88)

Dioicous. Dull green or dark green tufts, often embedded in alluvial detritus, 0.5–3.0(−5.0) cm high. Stems sparsely branched, central strand strong, sclerodermis weak, hyalodermis lacking. Axillary hairs 6–15 cells long, basal 1–4 yellowish. Leaves flexuose or curled when dry, erect-patent to spreading when moist, oblong-lanceolate to lingulate, obtuse and mucronate; margins recurved, thickened, papillose-crenulate above; costa stout, excurrent in mucro, adaxially 2–4 cells wide, cells elongate, in section with two stereid bands; basal cells narrowly rectangular, cells above irregularly quadrate-hexagonal, papillose with bifid papillae, opaque, 8–12 μm wide in mid-leaf, marginal band of cells 2–4-stratose forming a thick border. Perichaetial leaves sheathing. Setae 8–10 mm long; capsules erect, ellipsoid to cylindrical; lid longly rostrate; peristome teeth 32, filiform, papillose, weakly spirally coiled; calyptrae cucullate; spores finely papillose, 14–16 μm. Capsules occasional, spring. Laminal KOH reaction yellow or yellowish orange. On tree roots and boles or less commonly on rocks and walls above and below flood zone of streams and rivers, but also occasionally away from water. Lowland. Occasional to frequent in southern England except the south-west, very rare elsewhere in England and Wales, extending north to Durham and formerly Roxburgh. 47. GB152 + 42∗ . Mediterranean-Atlantic. Mediterranean and western Europe, extending north to Austria, Germany and the Netherlands, Asia, Algeria, Tunisia. Distinguished from all other members of the family by the thickened margins of the leaves. In this respect it resembles species of Cinclidotus but differs in leaves with recurved margins and papillose leaf cells. Cinclidotus fontinaloides has immersed capsules.

49 PSEUDOCROSSIDIUM R. S. Williams, BULL. TORREY BOT. CL., 1915 Dioicous. Plants forming cushions or turfs. Stems with central strand, sclerodermis usually differentiated, hyalodermis weak or absent. Axillary hairs of 3–8 usually hyaline cells. Leaves appressed, often spirally curved when dry, erect-patent to patent when moist, ovate to ligulate or lanceolate; margins revolute; costa excurrent, adaxial side 2–5 cells wide, cells quadrate, papillose, sometimes with photosynthetic filaments, in section adaxial stereid band small or absent, abaxial band strong; basal cells rectangular, cells above quadrate or hexagonal, usually densely papillose. Perichaetial leaves usually much larger than stem leaves. Capsules ellipsoid to cylindrical, straight or curved; peristome of 32 filiform spirally coiled segments; calyptrae cucullate. Laminal KOH reaction yellow to orange. A mainly montane genus of 16 species distributed through Europe, Middle East, Africa, N. and S. America, Australasia. Derivation: meaning resembling Crossidium (tassel-like, referring to the filaments on the costa).

49 Pseudocrossidium

295

Leaves acuminate, incurved and spirally twisted when dry, mid-leaf cells 10–14 μm wide 1. P. hornschuchianum Leaves obtuse and apiculate, tightly incurved when dry, cells 8–10 μm wide 2. P. revolutum 1 P. hornschuchianum (Schultz) R. H. Zander, Phytologia, 1979 Barbula hornschuchiana Schultz

(Fig. 89)

Green patches or scattered plants, 3–15 mm high. Leaves incurved, spirally twisted when dry, erect-patent when moist, giving shoots a stellate appearance when viewed from above, lanceolate, tapering from near base to acuminate apex; margins revolute ± from base to apex and often reaching costa in upper part of leaf; costa stout, excurrent in acuminate point, adaxial cells ± quadrate; basal cells rectangular, cells above quadrate-hexagonal, incrassate, papillose; pellucid, 10–14(−16) μm wide in mid-leaf. Perichaetial leaves larger than stem leaves, tapering to filiform apex. Setae orange-red; capsules narrowly ellipsoid; lid longly obliquely rostrate; peristome teeth long, filiform, spirally coiled; spores 8–10 μm. Capsules rare, winter, spring. n = 12, 13, 14. On calcareous soil on paths, in chalk and limestone grassland, old quarries, on sandy and gravelly ground, sand-dunes, in open situations. 0–330 m. Frequent or common on basic terrain in England and Wales, occasional in Scotland and Ireland. 109, H26, C. GB660 + 77∗ , IR40 + 9∗ , C3. Eurosiberian Southern-temperate. Europe north to southern Scandinavia, Asia Minor, Macaronesia, N. Africa, probably introduced in Massachusetts, British Columbia and Australia. Differs from P. revolutum in the leaves tapering ± from base to acuminate apex, twisted and less tightly incurved when dry and with larger cells. May be recognised in the field by the stellate appearance of moist shoots when viewed from above.

2 P. revolutum (Brid.) R. H. Zander, Phytologia, 1979 Barbula revoluta Brid.

(Fig. 89)

Dense dark green tufts or cushions, 3–15 mm high. Leaves tightly incurved when dry, giving plants a neat appearance, erect-patent when moist, narrowly lingulate to narrowly lanceolate, obtuse and apiculate; margins revolute ± from base to apex and reaching costa in upper part of leaf; costa stout and often widened above, usually excurrent in a mucro, adaxial cells ± quadrate; cells incrassate, basal rectangular, cells above quadrate with rounded lumens, papillose, opaque, 8–10 μm wide in mid-leaf. Setae flexuose, orange-red; capsules narrowly ellipsoid; lid longly obliquely rostrate; peristome teeth filiform, spirally coiled, fragile; spores 10–14 μm. Capsules rare to occasional, spring. In crevices in limestone and base-rich rocks, in old quarries, on walls and old buildings. 0– 500 m. Common in base-rich areas, elsewhere mainly in man-made habitats, in

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16 Pottiaceae

Fig. 89 1–5, Pseudocrossidium hornschuchianum: 1, leaves (×40); 2, leaf apex (×100); 3, basal cells; 4, mid-leaf cells; 5, capsule (×15). 6–10, P. revolutum: 6, leaves (×40); 7, leaf apex (×100); 8, basal cells; 9, mid-leaf cells; 10, capsule (×15). 11–13, Bryoerythrophyllum caledonicum: 11, leaves (×40); 12; basal cells; 13, marginal cells towards leaf apex. Cells ×420.

50 Bryoerythrophyllum

297

exposed situations. 107, H37, C. GB590 + 106∗ , IR125 + 4∗ , C3. SubmediterraneanSubatlantic. Europe north to southern Scandinavia, Iran, Madeira, Canary Islands, N. Africa. Brown rhizoidal gemmae of irregular size and shape, 300–600 × 100–400 μm, have been reported from Belgium (T. Arts, Lindbergia 14, 59–62, 1988) but have not been detected in British material. There is also a report of leaf gemmae.

50 BRYOERYTHROPHYLLUM P. C. CHEN, HEDWIGIA, 1941 Usually dioicous. Plants usually green above, reddish or brown below; stems with central strand. Axillary hairs with 0–3 brownish cells at base. Leaves ovate to lanceolate; margins recurved below, papillose-crenulate, toothed or not above, often with a border of 3–4 rows of thick-walled cells; costa ending below apex to excurrent, adaxial cells quadrate, papillose, abaxial cells elongate, papillose; basal cells rectangular, hyaline, cells above quadrate to shortly rectangular, incrassate, strongly papillose, opaque. Perichaetial leaves sheathing, larger than stem leaves. Capsules ellipsoid to cylindrical; peristome lacking to well developed, with 16 entire or deeply bifid straight to spirally coiled teeth. Laminal KOH reaction orange-red to red. Twenty-seven species world-wide. Derivation: meaning red-leaved moss.

1 Leaves toothed in upper 1/3 –1/2, (1−)2–3(−4) rows marginal cells in upper half of leaf incrassate, smooth, forming distinct border 3. B. caledonicum Leaves entire or with a few teeth near apex, unbordered 2 2 Plants green above, reddish brown below, leaves strongly curled when dry, linear-lanceolate, often toothed near apex 1. B. recurvirostrum Plants reddish brown throughout, leaves ± erect when dry, ovate-lanceolate, entire 2. B. ferruginascens 1 B. recurvirostrum (Hedw.) P. C. Chen, Hedwigia, 1941 Barbula recurvirostra (Hedw.) Dixon, B. rubella (Huebener) Mitt.

(Fig. 90)

Paroicous or synoicous. Tufts or patches, green above, rusty red or reddish brown below, to 5 cm high; stems not tomentose. Leaves flexuose to curved when dry, patent to spreading when moist, lanceolate to narrowly lanceolate, tapering from expanded basal part to acute apex; margins strongly recurved, papillose-crenulate, often irregularly and bluntly toothed towards apex; costa strong, ending below apex to percurrent, adaxial cells shortly rectangular, abaxial cells papillose in upper half of leaf; basal cells narrowly rectangular, hyaline, cells above quadrate to quadrate-hexagonal, papillose, opaque, c. 10 μm wide in mid-leaf. Setae deep red; capsules ellipsoid to cylindrical; lid narrowly conical, oblique; peristome teeth filiform, straight, short, c. 250 μm long; spores 14–20 μm Capsules frequent to

298

16 Pottiaceae

Fig. 90 Bryoerythrophyllum recurvirostrum: 1, leaves (×25); 2, leaf apex; 3, basal cells; 4, mid-leaf cells; 5, capsule (×15). 6–10, B. ferruginascens: 6, leaves (×40); 7, basal cells; 8, mid-leaf cells; 9, leaf apex; 10, rhizoidal gemma (×175). Cells ×420, apices ×100.

50 Bryoerythrophyllum

299

common, autumn to spring. n = 12 + m∗ , 13∗ , 13 + m. In sheltered, basic situations on thin soil, rocks, in crevices, on stream banks, old buildings, walls, in quarries, on tree boles in flood zone of streams and rivers. 0–1180 m. Very common. 112, H36, C. GB1306 + 109∗ , IR176 + 4∗ , C3. Circumpolar Boreo-temperate. Circumpolar Boreo-temperate. Europe north to Svalbard, Faeroes, Iceland, Turkey, Cyprus, Caucasus, Asia, N., C. and southern Africa, N. and C. America, Greenland, Tasmania, Hawaii. A variable species usually readily recognised by the reddish-brown older parts, the leaf margins toothed near the apex and the narrow hyaline basal cells. B. ferruginascens differs in the reddish brown colour of the whole plant, the slender tomentose stems and the presence of rhizoidal gemmae. Reddish brown rhizoidal gemmae, 25–30 μm diameter, have been reported by K. Saito (J. Hattori Bot. Lab. 60, 373–537, 1975) from Japanese specimens of B. recurvirostrum, but they have not been found in European plants.

2 B. ferruginascens (Stirt.) Giacom., Atti Ist. Bot. Univ. Pavia (ser. 5), 1957 (Fig. 90) Barbula ferruginascens Stirt., Barbula rubella var. ruberrima Fergusson, Barbula ¨ botelligera Monk. Sex unknown. Bright reddish brown tufts, patches or scattered plants, to 5 cm high; stems slender, tomentose. Leaves erect, slightly incurved when dry, patent to spreading from ± erect basal part when moist, lanceolate, tapering to ± acute apex; margins strongly recurved below, papillose-crenulate above, not toothed; costa stout, ending in apex, adaxial cells shortly rectangular, papillose, abaxial side papillose in upper part of leaf; cells incrassate, basal narrowly rectangular, hyaline, cells above irregularly quadrate, strongly papillose, opaque, 8–10(−12) μm wide in mid-leaf. Elongate reddish brown rhizoidal gemmae, 200–400 × 115–140 μm, usually present. Gametangia and sporophytes unknown. On base-rich soil and rock on cliffs and in ravines, in rock crevices on stream banks and sides of tracks. 0–1075 m. S. Devon, Hereford, Radnor, occasional to frequent in montane habitats in Wales, N. England and the Scottish Highlands, occasional in Ireland. 51, H13. GB153 + 9∗ , IR20 + 4∗ . Eurosiberian Boreal-montane. Montane and northern Europe, Faeroes, Iceland, Siberia, Japan(?), New Guinea, N. America, Greenland, Mexico. 3 B. caledonicum D. G. Long, J. Bryol., 1982 (Fig. 89) Sex unknown. Reddish-tinged lax tufts or patches, 1–3(−4) cm high. Leaves erect, appressed with curled tips when dry, erect-patent when moist, ovate-oblong, acute to rounded and weakly mucronate, shallowly keeled or not above; margins usually narrowly recurved below, weakly to coarsely toothed in upper 1/3 –1/2; costa reddish, ending below apex to shortly excurrent, adaxial cells ± quadrate, papillose, abaxial cells densely papillose in upper part of leaf; basal cells narrowly rectangular, hyaline, decreasing in width from costa to margins, cells above rounded-quadrate, densely papillose, opaque, 7–12 μm wide in mid-leaf, (1−)2–3(−4) rows marginal

300

16 Pottiaceae

cells smooth, incrassate, forming distinct border in upper half of leaf. Propagules, gametangia and sporophytes unknown. n = 13∗ . On permanently moist soil on sloping calcareous rock on ledges and by streams. 380–1060 m. Rare but locally frequent to abundant, Mid Perth, W. Inverness, Argyll, Rum, Skye. 4. GB12. Endemic (Oceanic Boreal-montane). Of similar colour to B. ferruginascens but differing in the broader, serrate, bordered leaves. This plant was referred to as a curious form of Leptodontium flexifolium in Dixon & Jameson (1924) but has recently been described as a new species. For a detailed account see D. G. Long, J. Bryol. 12, 141–57, 1982. R. H. Zander (Bryologist 89, 16–19, 1989) considers that this plant might be synonymous with B. andersoniana R. H. Zander & Sharp.

Tribe 2 Leptodontieae Stems lacking central strand.

¨ ¨ ¨ 51 LEPTODONTIUM (MULL. HAL.) HAMPE IN LINDB., OFVERS FORH. KONGL. SVENSKA VETENSK-AKAD., 1864 Dioicous. Plants forming tufts or short turfs; stems without central strand. Leaves flexuose or crisped when dry, patent to squarrose when moist, oblong-lanceolate, acute to obtuse; margins plane or recurved below, coarsely toothed above; costa ending below apex to excurrent, adaxial cells elongate; basal cells rectangular, cells above hexagonal, papillose or mamillose. Setae erect, flexuose; capsules ellipsoid to cylindrical; lid conical or rostrate; peristome without basal membrane, teeth 32, filiform, straight, smooth or finely papillose; annulus present; calyptrae cucullate. Laminal KOH reaction usually yellow. A world-wide genus of c. 40 species. Derivation: meaning slender tooth, referring to the peristome teeth. For an account of the two species described here see R. A. Rogeon & R. Schumacker, Bull. Soc. Bot. Centre Oest, NS 15, 81–102, 1984.

Leaf apices rounded to obtuse and apiculate, costa ending below apex in upper leaves, not gemmiferous 1. L. flexifolium Leaf apices acute, costa excurrent with clusters of gemmae at apex in upper leaves 2. L. gemmascens ¨ 1 L. flexifolium (Dicks.) Hampe in Lindb., Ofvers F¨orh. Kongl. Svenska Vetensk-Akad., 1864 (Fig. 91) Dull green to yellowish green or brownish green patches, 2–15 mm high. Leaves erect, flexuose when dry, soft, patent to spreading or recurved from erect base when moist, oblong-lanceolate to broadly lingulate or lingulate-spathulate, apex rounded or obtuse and apiculate; margins plane or recurved below, coarsely

51 Leptodontium

301

Fig. 91 1–3, Leptodontium flexifolium: 1, leaves (×30); 2, marginal cells from upper part of leaf; 3, capsule (×15). 4–6, L. gemmascens: 4, leaves (×30); 5, marginal cells from upper part of leaf; 6, gemmae (×250). 7–10, Hymenostylium recurvirostrum: 7, leaves (×40); 8, basal cells; 9, cells near leaf apex; 10, capsule (×20). 11–13, H. insigne: 11, leaves (×40); 12, basal cells; 13, cells near leaf apex. Cells ×420.

302

16 Pottiaceae

toothed above; costa stout, ending below apex, smooth on abaxial side; basal cells shortly rectangular to rectangular, cells above hexagonal, thin-walled to strongly incrassate, mamillose, opaque, 10–16(−20) μm wide in mid-leaf, a single marginal row pellucid. Deciduous bulbiform branches sometimes present; very rarely flaskshaped stem gemmae, composed of up to 15–16 cells, present. Setae flexuose, yellow; capsules narrowly ellipsoid to shortly cylindrical, straight or slightly curved; lid longly rostrate; peristome teeth straight, filiform; spores 12–14 μm. Capsules occasional, spring. On peaty soil, often on sites of fires, on heaths, moorland, woodland rides and soil on boulders. 0–750 m. Rare in lowland England and N. Scotland, occasional to frequent elsewhere, rare in Ireland. 84, H15. GB257 + 51∗ , IR14 + 4∗ . Oceanic Temperate. Belgium, Denmark, France, Germany, the Netherlands, Norway, Portugal, Spain, Nepal, Sikkim, Mongolia, China, Taiwan, Japan, Sumatra, Java, Lombok, New Guinea, Cameroon, Zaire, Kenya, N., C. and S. America. For an account of the gemmae of L. flexifolium see M. E. Newton & D. Boyce, J. Bryol. 14, 737–40, 1987.

2 L. gemmascens (Mitt.) Braithw., Brit. Moss Fl., 1887 (Fig. 91) Dull green tufts or patches, 2–10 mm high. Leaves erect, flexuose when dry, soft, spreading when moist, oblong-lanceolate to lanceolate, ± tapering to acute apex; margins plane or narrowly recurved below, coarsely toothed above; costa stout, excurrent with cluster of gemmae on excurrent portion in upper leaves; basal cells shortly rectangular, cells above hexagonal, thin-walled, papillose, opaque, 10–18 μm wide in mid-leaf, a single marginal row pellucid. Gemmae obovoid to shortly fusiform, 80–100 μm long, abundant on apices of upper leaves and in leaf axils. Gametangia and sporophytes unknown. On old thatch, bases of grass and Juncus tussocks on heaths, rarely on trees, ephemeral. Lowland. Rare and decreasing, scattered localities from S. Devon east to W. Kent and north to E. Gloucester, Hereford and Suffolk. 18. GB9 + 22∗ . Oceanic Temperate. Denmark, France, subantarctic Marion Is. This species is treated as vulnerable in the Red List of British Mosses.

52 HYMENOSTYLIUM BRID., BRYOL. UNIV., 1827 Dioicous. Plants forming tufts or cushions; stems often with reddish tomentum. Axillary hairs c. 8 cells long, 1–2 basal cells usually brownish. Leaves incurved or twisted when dry, spreading when moist, lingulate to linear-lanceolate; margins plane or recurved, entire; costa ending just below apex to excurrent, usually 3–4 cells wide on adaxial side, cells elongate; basal cells rectangular, cells above variable in shape, quadrate to rectangular, walls often porose, papillose, pellucid. Perichaetial leaves larger than stem leaves. Capsules ovoid, gymnostomous;

52 Hymenostylium

303

calyptrae cucullate. Laminal KOH reaction yellow. A world-wide genus of c. 18 mainly calcicole saxicolous species. Derivation: from the Greek words for membrane and pillar but it is not clear to what part of the moss this refers.

Leaves mostly 1.0–1.6 mm long, base not or only slightly expanded, costa 30–60 μm wide near base, longitudinal walls of basal cells non-porose 1. H. recurvirostrum Leaves mostly 1.6–2.4 mm long, base expanded, ± sheathing, costa (35−)60–100 μm wide near base, longitudinal walls of basal cells porose, 2. H. insigne 1 H. recurvirostrum (Hedw.) Dixon, Rev. Bryol. Lich´enol., 1934 (Fig. 91) ¨ Hal. Gymnostomum recurvirostrum Hedw., Weissia curvirostris (Erhr.) Mull. Dense green or dull green tufts or cushions, (0.5−)1.0–10.0 cm high. Leaves erect, appressed or flexuose or occasionally slightly twisted when dry, erect-patent to patent when moist, mostly 1.0–1.6 mm long, lanceolate to linear-lanceolate, basal part not or only slightly expanded, apex acute to acuminate; margins recurved on one or both sides, entire or papillose-crenulate; costa ending below apex, 30– 60 μm wide near base; cells incrassate, basal rectangular to narrowly rectangular, often with oblique transverse walls thinner than non-porose longitudinal walls, cells above ± shortly rectangular, smooth to strongly papillose, towards apex rectangular to ± quadrate, pellucid, 8–12 μm wide. Capsules erect, ovoid, gymnostomous; lid longly obliquely rostrate, attached to columella and sometimes persisting; columella lengthening at maturity; peristome lacking; spores 18–20 μm. Capsules occasional, autumn. n =12 + m, 13∗ . On damp, basic rock faces, boulders, in crevices, on limestone pavement, old walls and heavy metal mine-waste. 0–1070 m. Cornwall, N. Somerset, rare in Wales, occasional to frequent from Derby north to Shetland, rare in Ireland. 55, H16. GB194 + 22∗ , IR16 + 5∗ . Circumpolar Boreo-temperate. Europe north to Svalbard, Iceland, Turkey, Madeira, Asia, Algeria, N. America, Greenland, Mexico, Peru. Var. cataractacum (Schimp.) Podp. appears to be a dustbin taxon in which aberrant forms of H. recurvirostrum are placed and cannot be maintained.

2 H. insigne (Dixon) Podp., Consp. Musc. Eur., 1954 (Fig. 91) Gymnostomum insigne (Dixon) A. J. E. Sm., G. recurvirostrum var. insigne (Dixon) P. W. Richards & E. C. Wallace, Weissia curvirostris var. insigne (Dixon) H. Schmidt Dark green to brownish green tufts or patches, 4–12 cm high. Leaves loosely incurved when dry, patent to spreading when moist, mostly 1.6–2.4 mm long, basal part erect, ± sheathing, limb gradually tapering to acuminate apex; margins recurved below, not papillose; costa ending in or below apex, (35−)60–100 μm

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16 Pottiaceae

wide near base; cells incrassate, basal rectangular to narrowly rectangular, transverse walls ± oblique, thinner than often porose longitudinal walls, cells above irregularly rhomboidal to ± quadrate, smooth, pellucid, 8–12 μm wide towards apex. Capsules ellipsoid, very rare. Calcareous montane rock ledges and humid lowland ravines. 0–680 m. Rare, western Scotland from Mid Perth north to W. Sutherland, Sligo, Leitrim. 8, H2. GB14 + 5∗ , IR4. Oceanic Boreal-montane. Spain, British Columbia, Peru. Although treated by some recent authors (e.g. Zander, 1993) as a variety of the previous species, this plant is distinct, differing from H. recurvirostrum in the leaves loosely incurved when dry, more widely spreading when moist, with expanded sheathing basal part, the often porose basal cell walls and the non-papillose upper cells.

Tribe 3 Barbuleae Stems with central strand or if absent then costa in section with only one stereid band.

¨ 53 ANOECTANGIUM SCHWAGR., SP. MUSC. FROND. SUPPL. 1, 1811 Dioicous. Plants tufted, stems tomentose, central strand present. Axillary hairs 3–10 cells long, all hyaline or basal 1–2 brownish. Leaves appressed when dry, erect-patent when moist, lingulate to lanceolate, channelled above; margins plane or narrowly recurved below, papillose-crenulate above; costa ending in or below apex, on adaxial side 2–3 cells wide, cells elongate, in section with one stereid band; basal cells rectangular, cells above rounded-quadrate, papillose, opaque. Perichaetia and perigonia on short lateral branches. Setae long; capsules ovoid to ellipsoid; gymnostomous; calyptrae cucullate. Laminal KOH reaction yellow to yellowish orange. A world-wide genus of about 40 species. Derivation: meaning open vessel, from the wide-mouthed capsules of some species.

1 A. aestivum (Hedw.) Mitt., J. Linn. Soc. Bot., 1869 ¨ A. compactum Schwagr.

(Fig. 92)

Dense soft tufts or cushions, bright green above, light brown below, 2–10 cm high; stems slender, often with well defined annual growth zones, tomentose below with reddish brown rhizoids. Leaves spirally curled when dry, patent when moist, keeled, ovate to lanceolate, acute; margins usually, plane papillose-crenulate; costa usually ending in or below apex, adaxial cells elongate; cells incrassate, basal rectangular, cells above rounded-hexagonal, papillose, opaque, 8–10 μm wide in mid-leaf, apical cell clearly defined, pellucid. Setae lateral, 7–10 mm long; capsules emerging 1–2 mm above leaves, ellipsoid, gymnostomous; lid with oblique subulate beak; spores 12–16 μm. Capsules rare, spring, summer. n = 13. On usually basic moist or sheltered rocks and in crevices on cliffs, in ravines, by waterfalls. 0–1180 m. Rare in S. Wales, frequent or common in N. Wales, N. W. England and

53 Anoectangium

305

Fig. 92 1–4, Anoectangium aestivum: 1, leaves; 2, mid-leaf cells; 3, leaf apex; 4, capsule. 5–11, Gyroweisia tenuis: 5, plant (×10); 6, 7, lower and upper leaves: 8, basal cells; 9, apical cells; 10, protonemal gemmae (×45); 11, capsule mouth (×40). 12–17, G. reflexa: 12, plant (×10); 13, 14, lower and upper leaves; 15, basal cells; 16, apical cells; 17, capsule mouth (×40). Leaves ×40, cells ×420.

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16 Pottiaceae

the Scottish Highlands, north to Caithness, very rare elsewhere, Stafford, Derby, rare to occasional in W. Ireland. 49, H17. GB278 + 15∗ , IR30 + 10∗ . European Boreal-montane. Montane and northern Europe north to Fennoscandia, Faeroes, Iceland, Caucasus, Himalayas, Japan, Philippines, Canary Islands, Madeira, N. Africa, Cameroon, N., C. and S. America, Greenland. 54 GYROWEISIA SCHIMP., SYN. MUSC. EUR. (ED. 2), 1876 Dioicous. Plants very small, gregarious. Stems mostly simple, with or without central strand. Leaves appressed, incurved when dry, erect-patent to recurved when moist, linear-lanceolate to lingulate, apex usually obtuse or rounded; margins plane, papillose-crenulate; costa ending below apex, 2–4 cells wide on adaxial side, cells elongate, in section with adaxial stereid band weak or absent; basal cells rectangular, hyaline, cells above rounded-quadrate, incrassate, papillose or smooth. Setae straight; capsules erect, ovoid or ellipsoid; lid conical; peristome rudimentary or absent; annulus of 2–3 rows large cells; calyptrae cucullate. Six species distributed through Europe, Middle East, China, N. Africa, N. America. Derivation: from the well developed annulus circling the capsule mouth and the resemblance to Weissia.

Peristome absent, upper and perichaetial leaves patent to reflexed 1. G. tenuis Rudimentary peristome present, upper and perichaetial leaves strongly recurved to squarrose 2. G. reflexa 1 G. tenuis (Schrad. ex Hedw.) Schimp., Syn. Musc. Eur. (2nd edn.), 1876 (Fig. 92) ¨ Hal. Weissia tenuis (Schrad. ex Hedw.) Mull. Plants gregarious, 1.0–2.5 mm high, forming light green patches. Leaves erect to spreading, flexuose when dry, patent or spreading when moist, lower lingulate, apex rounded, upper longer, lingulate-lanceolate, apex rounded or obtuse; margins plane, papillose; costa ending below apex, 20–30 μm wide near base; basal cells narrowly rectangular, in lower leaves to 50 μm long, in upper to 90 μm long, cells above quadrate-rectangular, papillose, ± pellucid, towards apex irregularly quadrate, c. 8 μm wide. Perichaetial leaves patent to reflexed from sheathing base. Pale ovoid or irregular protonemal gemmae, 50–70 μm long, sometimes present. Setae yellowish, 3–5 mm long; capsules narrowly ellipsoid to subcylindrical, gymnostomous; lid obliquely rostrate; spores 8–10 μm. Capsules common in the north and west, rare in the south and east, summer, autumn. n = 13. On damp shaded often vertical chalk, limestone, sandstone, mortar, old brickwork, particularly by streams and pools, shade tolerant. 0–400 m. Occasional to frequent in England and S. E. Scotland, rare in Wales and much of Scotland, extending north to Shetland, occasional in Ireland. 98, H24. GB345 + 52∗ , IR25 + 11∗ . European

55 Gymnostomum

307

Temperate. Europe north to Scandinavia, Turkey, Syria, Iran, China, Tunisia, N. America. 2 G. reflexa (Brid.) Schimp., Syn. Musc. Eur. (ed. 2), 1876 Weissia reflexa Brid.

(Fig. 92)

Plants 1.5–2.0 mm high. Lower leaves erect-patent, upper and perichaetial leaves much larger, crowded, strongly recurved to squarrose when moist, lingulate, sometimes with expanded basal part, apex rounded to acuminate; margins plane, entire; costa ending below apex; basal cells rectangular, 2–4 times as long as wide, cells above shortly rectangular, incrassate, papillose, towards apex ± quadrate, 6–8 μm wide. Protonemal gemmae similar to those of G. tenuis often present. Perichaetial leaves with sheathing bases, acuminate. Setae flexuose, yellowish; capsules ovoid to ellipsoid, lid conical, oblique; 16 irregular rudimentary peristome teeth present, soon falling; spores 10–14 μm. Capsules common, winter. Found in a sandstone quarry in Nuneaton, Stafford in 1933 and last seen in 1938. The site is now a housing estate. 1. GB1∗ . Mediterranean region, Turkey, Madeira, N. Africa, N. America. Some forms of G. tenuis approach this plant but the upper leaves are less crowded and not strongly recurved or squarrose. For the occurrence of this plant in Britain see Rep. Brit. Bryol. Soc. 3(2), 118, 1933 under Weissia tenuis.

55 GYMNOSTOMUM NEES & HORNSCH. IN NEES ET AL., BRYOL. GERM., 1823 Dioicous. Plants forming lax or dense tufts. Leaves appressed, ± incurved when dry, erect-patent to spreading when moist, linear-lanceolate to lanceolate, acute to obtuse; margins plane or recurved, entire or papillose-crenulate; costa ending below apex, on adaxial side 2–4(−6) cells wide, cells usually quadrate or rectangular, in section with adaxial stereid band weak or lacking; basal cells rectangular, cells above quadrate to quadrate-hexagonal, papillose, opaque. Setae long, straight; capsules ovoid or ellipsoid, smooth; lid longly rostrate, oblique; annulus of one row of small persistent cells; peristome absent; calyptrae cucullate. Laminal KOH reaction yellow to yellowish orange. A ± world-wide genus of c. 25 species. Derivation: meaning naked mouth, referring to the absence of peristome teeth.

1 Costa 60–110 μm wide near leaf base, cells in upper part of leaf (8−)10–14 μm wide 3. G. aeruginosum Costa 30–45 μm wide near base, upper cells 5–10 μm wide 2 2 Leaves lingulate to ligulate, 3–7 times as long as wide, axillary gemmae lacking 1. G. calcareum Leaves ovate to ovate-lanceolate, 2–4 times as long as wide, axillary gemmae often present 2. G. viridulum

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1 G. calcareum Nees & Hornsch. in Nees et al., Bryol. Germ., 1823 ¨ Hal. Weissia calcarea (Nees & Hornsch.) Mull.

(Fig. 93)

Dense bright green turfs or cushions, 5–20 mm high. Leaves appressed, slightly twisted when dry, spreading to recurved when moist, lanceolate to ligulate, 0.5–1.0 × 0.1–0.2 mm, 5–7 times as long as wide, obtuse to subacute; margins plane, papillose-crenulate, costa reaching nearly to apex, 30–40 μm wide near base, in section circular near base, with very well developed abaxial stereid band, poorly developed adaxial band; basal cells near costa rectangular, smooth, lumens with rounded corners, c. 10 × 30 μm, cells above unistratose, strongly papillose, opaque, quadrate, incrassate, lumens rounded, 5–10 μm wide in upper part of leaf. Perichaetial leaves wider than stem leaves. Setae pale yellow; capsules ellipsoid to cylindrical, gymnostomous; lid obliquely rostrate; spores 8–12 μm. Capsules rare, spring, summer. n = 13. On damp sheltered calcareous rocks, rarely on mortar on walls. 0–550 m. Occasional in the Pennines and western Scottish Highlands, very rare elsewhere, in widely scattered localities from E. Cornwall and W. Sussex north to W. Sutherland, rare in Ireland. 28, H12. GB75 + 7∗ , IR17 + 3∗ . Eurosiberian Southern-temperate. Europe, extending north to Sweden and Finland, Turkey, Cyprus, Caucasus, Middle East, Himalayas, Tibet, China, Azores, Canary Islands, N. and southern Africa, N. America, S. Africa, Australasia. R. H. Zander (Bryologist 80, 233–69, 1977) treats G. calcareum as a synonym of G. aeruginosum, but the two differ in size, colour, leaf shape, cell size and the form of the costa. For a discussion of this see M. E. Newton, J. Bryol. 12, 343–9, 1983.

2 G. viridulum Brid., Bryol. Univ., 1826 ´ ´ ´ G. luisieri (Sergio) Sergio & Crundw., Gyroweisia luisieri Sergio

(Fig. 93)

Dense bright green turfs, 1.5–5.0 mm high. Leaves appressed when dry, spreading or recurved when moist, 0.3–0.7 × 0.15–0.30 mm, 2–4 times as long as wide, ovate to ovate-lanceolate, obtuse or occasionally subacute; margins plane, papillose-crenulate; costa 30–35 μm wide near base, ± reaching apex, in section circular towards base, with abaxial stereid band only; basal cells near costa c. 20 × 40 μm, smooth, cells above unistratose, rounded-quadrate, papillose, opaque, 5–10 μm wide in upper part of leaf. Ovoid multicellular axillary gemmae, 40–90 × 20–30 μm, frequently present; protonemal gemmae also sometimes present. Perichaetial leaves wider than stem leaves. Setae pale yellow; capsules ellipsoid. gymnostomous; lid obliquely rostrate; spores 10– 12 μm. Capsules very rare. In sheltered or exposed situations in limestone crevices, on limestone soil, limestone wall tops and crumbling mortar. Lowland. Rare, from S. Devon and S. Hampshire north to Caernarfon, S. W. and N. W. Yorkshire, Alderney. 16, H10, C. GB27 + 2∗ , IR11 + 1∗ , C1. Mediterranean-Atlantic. Mediterranean region, extending north to Czechoslovakia, Switzerland, Belgium,

55 Gymnostomum

Fig. 93 1–5, Gymnostomum calcareum: 1, plant (×25); 2, leaves (×75); 3, basal cells; 4, cells near leaf apex; 5, capsule (×20). 6–10. G. viridulum: 6, plant (×50); 7, leaves (×125); 8, basal cells; 9, leaf apex; 10, axillary gemma (×420). Cells ×420.

309

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W. France, Germany, Turkey, Caucasus, Middle East, N. W. India, W. Asia, N. and E. Africa. Only recently recognised as occurring in the British Isles, having in the past been confused with G. calcareum. It differs from that species in leaf shape, width of basal cells and frequent presence of gemmae. Small forms of G. aeruginosum may be distinguished from G. viridulum by the leaves distinctly crisped when dry, the wider costa with adaxial stereids in section and the larger upper cells. Leptobarbula berica differs from G. calcareum and G. viridulum in the more longly tapering leaves, and Gyroweisia tenuis may be distinguished by the larger basal cells and the presence of bottle-shaped protonemal gemmae. For a detailed account of G. calcareum and G. viridulum see H. L. K. Whitehouse & A. C. Crundwell, J. Bryol. 16, 561–79, 1991.

3 G. aeruginosum Sm., Fl. Brit., 1804 ¨ ¨ Hal. Weissia rupestris (Schwagr.) Mull.

(Fig. 94)

Tufts or cushions, dull green above, reddish brown below, 0.5–8.0 cm high. Leaves twisted when dry, erect-patent to patent when moist, variable in shape, linear, ligulate, linear-lanceolate or ovate-lanceolate, basal part sometimes expanded, apex acute to subobtuse; margins plane, sometimes obscurely toothed below, erect or incurved and papillose-crenulate above; costa ending below apex, stout, 60– 100 μm wide near base, in section 1.5–2.0 times as wide as thick, 3 cells thick towards apex, with adaxial and abaxial stereid bands; cells incrassate, basal rectangular or narrowly rectangular, cells above unistratose or bistratose, irregularly quadrate, papillose or strongly papillose, opaque, near apex (8−)10–14 μm wide. Perichaetial leaves larger than stem leaves, base sheathing. Setae 4–8 mm long; capsules ellipsoid; lid obliquely rostrate, gymnostomous; spores 8–14 μm. Capsules occasional, late summer, autumn. n = 13∗ . On damp or wet usually basic rocks, in flushes, moist crevices on cliffs, in ravines, on coastal cliffs, old walls. 0–1175 m. Absent from lowland England, rare in S. W. England, occasional to frequent elsewhere, occasional in Ireland. 75, H25. GB465 + 38∗ , IR54 + 11∗ . Circumpolar Boreo-temperate. Europe north to Fennoscandia, Faeroes, Iceland, Turkey, Caucasus, China, Japan, New Guinea, Madeira, Canary Islands, N. and C. America, Peru. 56 MOLENDOA LINDB., UTKAST. EUR. BLADMOSS, 1878 Dioicous. Plants forming turfs. Stems with central strand. Leaves appressed, twisted, incurved when dry, spreading or spreading-recurved when moist, ovate to ligulate or linear-lanceolate, acute to rounded; margins plane or recurved below, entire or sinuose, sometimes denticulate at shoulders of basal part; costa ending below apex to excurrent, 2–7 cells wide on adaxial side, cells quadrate to elongate, in section with or without stereid bands; basal cells rectangular, cells above quadrate or rectangular, often bistratose at margins, papillose, papillae simple or multifid. Perichaetia on short lateral branches; perichaetial leaves sheathing. Capsules cylindrical; lid longly rostrate; peristome lacking; calyptrae

56 Molendoa

311

Fig. 94 1–6, Molendoa warburgii: 1, plant (×10); 2, leaves (×65); 3, mid-leaf cells; 4, leaf apex; 5, capsule (×25); 6, gemmae (×280). 7–10, Gymnostomum aeruginosum: 7, leaves (×40); 8, basal cells; 9, leaf apex; 10, capsule (×20). Cells ×420.

cucullate. Fifteen species distributed through all continents except Australasia and Antarctica. Derivation: named after the German bryologist Ludwig Molendo (1833–1902).

1 M. warburgii (Crundw. & M. O. Hill) R. H. Zander, Bull. Buffalo Soc. Nat. Sci., 1993 (Fig. 94) Anoectangium warburgii Crundw. & M. O. Hill Small to extensive yellowish green patches or scattered plants, to 1 cm high; stems often innovating from below; rhizoids deep reddish brown. Lower leaves minute, upper larger, appressed when dry, erect-patent to patent when moist, ovate to

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lanceolate, to 0.6 mm long, apices rounded; margins plane, papillose-crenulate; costa broad, ending below apex, lamina cells extending over costa in upper part of leaf; extreme basal cells shortly rectangular, cells elsewhere ± quadrate, gradually becoming smaller towards apex, obscure with papillae, cells in mid-leaf c. 8 μm wide. Green to brownish ± ovoid to fusiform several-celled gemmae, 80–110 μm long with thin cell walls, frequently present in axils of lower leaves. Setae lateral; capsules narrowly ovoid, gymnostomous; lid longly rostrate. Capsules rare, spring or early summer. On moist usually vertical rock by streams and waterfalls and in seepage areas on rock. 0–1070 m. Occasional in N. Wales, occasional to frequent in the western and central Scottish Highlands from Arran and Stirling north to Sutherland, W. Mayo. 23, H1. GB112 + 1∗ , IR1. Oceanic Boreal-montane. Endemic. Confused in the past with Gymnostomum calcareum which, however, occurs in drier and more exposed habitats, forms dense bright green tufts and has less strongly papillose leaves with more extensive and markedly longer basal cells. Anoectangium aestivum is larger but depauperate plants may be distinguished by the single translucent well defined apical cell of the leaves. For an account of this plant see A. C. Crundwell & M. O. Hill, J. Bryol., 9, 435–40, 1977.

57 BARBULA HEDW., SP. MUSC. FROND., 1801 Dioicous. Plants forming small tufts, cushions or short turfs. Stems with central strand. Axillary hairs 2–10 cells long, usually completely hyaline. Leaves often contorted or twisted when dry, spreading when moist, spathulate, lingulate, lanceolate or elongate-triangular, acute or obtuse; margins usually recurved, papillosecrenulate; costa percurrent or shortly excurrent, adaxial and abaxial cells usually elongate, in section with two stereid bands; basal cells rectangular, cells above ± quadrate, papillose, opaque. Perichaetial leaves differing from stem leaves or not. Capsules ovoid to cylindrical; peristome of 32 spirally coiled filiform segments. Laminal KOH reaction usually yellowish or yellowish orange. A cosmopolitan genus of c. 200 species. Derivation: from the Latin for beard, referring to the peristomes.

1 Setae yellowish, leaf margins narrowly recurved on one or both sides below, costa ending below apex, rarely shortly excurrent Setae dark red or purplish, leaf margins recurved almost to apex, costa excurrent 3. B. unguiculata 2 Plants mostly 2–5 mm high, yellowish green or bright green, leaf margins not undulate, cells strongly papillose, opaque 2. B. convoluta Plants mostly 5–10 mm high, dark green, leaf margins undulate, cells papillose, pellucid 3. B. sardoa 1 B. convoluta Hedw., Sp. Musc. Frond., 1801 (Fig. 95) Bright green or yellowish green tufts or patches, sometimes extensive, usually 2–25 mm high; stems tomentose below; central strand lacking Leaves strongly curled when dry, erect-patent to spreading or recurved when moist,

57 Barbula

313

Fig. 95 1–7, Barbula convoluta: 1, plant (×5); 2, leaves (×30); 3, leaf apex (×70); 4, basal cells; 5, mid-leaf cells; 6, capsule (×15); 7, rhizoidal gemmae (×175). 8–12, B. unguiculata: 8, leaves (×30); 9, leaf apex (×70); 10, basal cells; 11, mid-leaf cells; 12, capsule (×10). 13, B. sardoa: leaf (×30). Cells ×420.

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oblong-lanceolate, 0.6–0.9 mm long obtuse to acute; margins narrowly recurved on one or both sides below, papillose-crenulate; costa strong, green to brownish, ending in or below apex or shortly excurrent in apiculus, adaxial cells elongate; cells ± incrassate, basal irregularly rectangular, chlorophyllose narrower towards margins, cells above quadrate or quadrate-hexagonal, strongly papillose, opaque, 8–10(−12) μm wide in mid-leaf. Brown spherical rhizoidal gemmae, 110–140 μm long, often present. Perichaetial leaves convolute, inner ecostate. Setae pale yellow; capsules ellipsoid to subcylindrical, straight or slightly curved, c. 1.5 mm long excluding longly rostrate lid; peristome of long filiform spirally coiled segments; spores 8–10 μm. Capsules occasional, spring, summer. n = 11, 13, 14∗ . In open sites on disturbed soil, waste ground, paths, tarmac, arable fields, in gardens, soil-filled crevices in walls and old buildings. 0–490 m. Very common at low altitudes. 112, H40, C. GB1763 + 82∗ , IR290 + 6∗ , C8 + 1∗ . Circumpolar Wide-temperate. Widespread in the Northern Hemisphere, C. and S. Africa, New Zealand (probably introduced in Southern Hemisphere localities). 2 B. sardoa (Schimp.) J.-P. Frahm, J. Bryol., 2004 B. convoluta var. commutata (Jur.) Husn. Plants forming dense tufts 5–10 (–25) mm high; stems with central strand. Leaves strongly curled when dry, spreading to recurved when moist, 0.8–1.5 mm long, lingulate, acute to obtuse; margins of at least upper leaves undulate; basal cells rectangular, hyaline, cells above quadrate to quadrate-hexagonal, papillose, pellucid, 8–10 (–12) μm wide in mid-leaf. Gemmae not known. Setae pale yellow; capsules cylindrical, c. 2 mm long excluding lid. On base-rich soil, walls and in rock crevices. Occasional in N. Britain, frequent elsewhere. 77, H31, C. South and Central Europe. The status of this plant was regarded as debatable but it has been shown by J.-P. Frahm & J. Ahmed (J. Bryol., 26, 29–35, 2004) that it is a good species.

3 B. unguiculata Hedw., Sp. Musc. Frond., 1801 (Fig. 95) Plants forming patches, bright green above, reddish brown below, mostly 5–25 mm high; stems orange-red, not tomentose. Leaves twisted or incurved when dry, erect-patent, patent or recurved when moist, lingulate to narrowly lingulate or lingulate-lanceolate, apex obtuse or rounded, apiculate, occasionally acute or acuminate; margins recurved almost to apex, papillose-crenulate; costa stout, green to brownish, excurrent in thick point, adaxial cells quadrate; basal cells rectangular or narrowly rectangular, shorter towards margins, above ± quadrate, incrassate, papillose, opaque, 10–14 μm wide in mid-leaf. Perichaetial leaves larger than stem leaves with slightly sheathing bases. Setae dark red to purplish; capsules narrowly ellipsoid, straight; lid longly rostrate; peristome deeply bifid into filiform spirally coiled segments; spores 10–14 μm. Capsules frequent, summer to spring. n = 11∗ , 11 + m, 12 + m∗ , 13∗ , 13 + m∗ , 13 + 2m∗ , 14, 14 + 2m, 16∗ , 24∗ . On disturbed soil in open or slightly sheltered, especially man-made habitats, on paths, in fields, gardens, waste places, stony ground, crevices of walls and old

58 Didymodon

315

buildings. 0–530 m. Very common in lowland areas. 112, H38, C. GB1695 + 77∗ , IR248 + 19∗ , C3 + 1∗ . Circumpolar Wide-temperate. Europe north to Fennoscandia, Faeroes, Iceland, Turkey, Cyprus, Asia, Macaronesia, C. and S. Africa, N. America, Mexico, southern S. America, Australia, New Zealand (probably introduced in Southern Hemisphere localities). A very variable species. A form with narrower leaves with more acute tapering apices is referred to as var. cuspidata (Schultz) Brid., but with the range of forms that exist it is not possible to delimit this plant satisfactorily and it is not recognised here. B. unguiculata may be confused with B. convoluta, but the latter differs in the tomentose stems, leaf shape, leaf margins plane or only narrowly recurved below, the costa rarely excurrent and yellow setae.

58 DIDYMODON HEDW., SP. MUSC. FROND., 1801 Usually dioicous. Plants forming tufts, cushions or patches. Stems with central strand. Axillary hairs c. 5 cells long, basal 1–2 cells brownish. Leaves appressed, curved or crisped when dry, erect-patent to squarrose when moist, lanceolate to narrowly lanceolate, acute to obtuse or rounded; margins plane, recurved or revolute; costa below apex to excurrent, usually smooth on abaxial side in upper half of leaf, adaxially 2–4(−8) cells wide, cells quadrate or elongate, stereid bands present or adaxial band weak or absent; basal cells quadrate to rectangular, upper cells quadrate or rounded-hexagonal, incrassate or not, smooth, papillose or mamillose. Capsules ellipsoid to cylindrical; peristome teeth 16, perforated to deeply bifid, long or short, straight or spirally coiled. A temperate and montane genus of about 120 species. Derivation: Alluding to the bifid peristome teeth. For an account of Central European species of Didymodon, which includes descriptions or mention of all British and Irish species, see J. Kuˇcera, Meylania 19, 1–49, 2000.

1 Adaxial cells of costa in at least upper half of leaf ± isodiametric, rarely rectangular 2 Adaxial cells of costa elongate 14 2 At least upper leaves with costa excurrent in acute or acuminate point 3 Costa ending in or below apex or if excurrent then in a stout point 6 3 Leaves broadly ovate, costa stout, 70–100 μm wide near base, numerous axillary gemmae present 11. D. cordatus Leaves linear-lanceolate to ovate, costa narrower, gemmae lacking 4 4 Leaves linear-lanceolate 9. D. insulanus Leaves ovate to lanceolate 5 5 Plants not very slender, in patches or scattered, leaf cells smooth, ± rounded, annulus not separating 1. D. acutus Plants very slender, in dense rufts, leaf cells often papillose, particularly on the abaxial side, quadrate to rounded-quadrate, annulus of one row of large separating cells 2. D. icmadophilus 6 Leaf margins bistratose at least above, axillary gemmae often present 7 Leaf margins unistratose throughout, gemmae rarely present 9

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16 Pottiaceae

7 Leaf cells distinctly papillose, 6–8 μm wide in mid-leaf, gemmae if present in British and Irish material very rare 5. D. nicholsonii Leaf cells slightly papillose, 8–10 μm wide in mid-leaf, axillary gemmae almost always present although sometimes sparsely so 8 8 Leaves lanceolate, tapering to stout blunt apex, cells not mamillose, widespread plant 3. D. rigidulus Leaves ovate to lanceolate, cells mamillosely bulging, very rare montane plant 4. D. mamillosus 9 Leaf apices often missing, margins undulate, sinuose and sometimes notched or irregularly toothed 12. D. sinuosus Leaf apices present, margins entire or papillose-crenulate, not undulate, notched or toothed 10 10 Leaves imbricate when dry, ovate-lanceolate to broadly ovate, apices acute to rounded 10. D. luridus Leaves erect-flexuose, crisped or incurved when dry, linear-lanceolate or ligulate-lanceolate to ovate, acuminate to acute 11 11 Leaves erect-flexuose when dry, lanceolate to ovate 8. D. vinealis Leaves usually crisped, curled or incurved when dry, linear-lanceolate or ligulate-lanceolate 12 12 Basal part of leaves expanded, with very narrow marginal cells 7. D. australasiae var. umbrosus Leaf bases not expanded, basal marginal cells not differentiated 13 13 Plants 2–3 mm high, leaves incurved when dry, ligulate-lanceolate, chains of axillary gemmae sometimes present 6. D. glaucus Plants 5–50 mm high, leaves crisped when dry, linear-lanceolate, gemmae lacking 9. D. insulanus 14 Leaves lingulate from ovate or lanceolate basal part, apices rounded to obtuse or shortly acute 13. D. tophaceus Leaves ovate or ovate-lanceolate, tapering to acute or acuminate apex 15 15 Leaves patent to recurved, plants to 2.5(−3.0) cm high 16 Leaves squarrose or if recurved then plants 3–9 cm high 18 16 Plants to c. 6 mm high, leaf margins entire, sausage-shaped rhizoidal gemmae present 16. D. tomaculosus Plants to 30 mm high, leaf margins entire or papillose-crenulate, rhizoidal gemmae lacking 17 17 Leaves usually recurved when moist, upper mostly 1.2–2.4 mm long, acuminate, peristome teeth spirally coiled 15. D. fallax Leaves patent or spreading when moist, upper mostly 1.8–4.0 mm long, apex acute to obtuse, peristome teeth straight 14. D. spadiceus 18 Plants to 2.5 cm high, leaves 0.8–1.8 mm long, basal cells not incrassate 17. D. ferrugineus Plants 3–9 cm high, leaves 2–4 mm long, basal cells incrassate 18. D. maximus

58 Didymodon

317

Section Didymodon Leaves erect to spreading when moist, concave; margins plane or recurved below; costa percurrent to excurrent, adaxial cells in upper half quadrate, in section adaxial stereid band usually lacking; lamina cells quadrate, smooth or papillose, papillae simple or bifid. Peristome teeth short, hardly twisted. 1 D. acutus (Brid.) K. Saito, J. Hattori Bot. Lab., 1975 (Fig. 96) ¨ Barbula acuta (Brid.) Brid., B. gracilis (Schleich.) Schwagr., D. rigidulus var. gracilis (Schleich.) R. H. Zander Green to brownish patches or scattered plants, 3–20 mm high. Leaves appressed, flexuose when dry, erect-patent when moist, concave, ovate to lanceolate, gradually tapering to acute apex; margins narrowly recurved below, entire; costa strong, occupying most of upper part of leaf, in upper leaves shortly to longly excurrent, adaxial cells rounded-quadrate; basal cells rectangular, cells above rounded to rounded-quadrate, incrassate, smooth, pellucid, 8–10(−15) μm wide in mid-leaf. Capsules ellipsoid or narrowly ellipsoid; annulus not separating; lid obliquely rostrate; peristome teeth filiform, spirally coiled; spores 9–12 μm. Capsules rare, late winter, spring. n = 13. Usually in small quantity in sparse turf or on bare soil in exposed situations in chalk and limestone grassland and on sand-dunes, very rarely on base-rich montane ledges. 0–600 m. Occasional but widely distributed from W. Cornwall east to W. Kent and north to Westmorland, very rare in Scotland, Angus, N. Aberdeen, Banff, rare in Ireland, formerly Jersey and Guernsey. 37, H8, C. GB57 + 17∗ , IR4 + 3∗ , C4∗ . Circumpolar Southern-temperate. Europe north to Svalbard, Caucasus, Cyprus, Turkey, Macaronesia, N. and C. America. Small axillary gemmae have been reported in D. acutus, but it is possible that such plants are misidentified D. rigidulus. It has also been suggested that some gatherings named D. acutus belong to D. icmadophilus; the situation requires further investigation.

¨ Hal.) K. Saito, J. Hattori Bot. Lab., 1975 2 D. icmadophilus (Schimp. ex Mull. (Fig. 96) ¨ Hal., D. acutus var. icmadophilus (Schimp. Barbula icmadophila Schimp. ex Mull. ¨ Hal.) R. H. Zander, D. rigidulus var. icmadophilus (Schimp. ex Mull. ¨ ex Mull. Hal.) R. H. Zander Plants very slender, forming dense blue-green tufts or patches. Leaves appressed, slightly flexuose when dry. Patent when moist, concave, lanceolate, tapering to long acuminate apex consisting mainly of costa; margins narrowly recurved below, entire; costa strong, excurrent, often longly so; basal cells shortly rectangular, cells above quadrate to rounded-quadrate, often papillose, especially on the adaxial side. Capsules narrowly ellipsoid; annulus of a single row of separating cells. Capsules unknown in the British Isles. On basic ledges on cliffs and in gullies, on crumbling rock and in short turf. 60–600 m. Very rare, Cumberland, Mid and E. Perth, Banff, Skye, W. Sutherland, Sligo (old record). 6, H1.

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Fig. 96 1–5, Didymodon acutus: 1, leaves; 2, leaf apex; 3, basal cells; 4, mid-leaf cells; 5, adaxial cells of costa at middle of leaf. 6–9, D. icmadophilus: 6, leaf; 7, leaf apex; 8, basal cells; 9, mid-leaf cells. 10–16, D. rigidulus: 10, leaves; 11, leaf apex; 12, basal cells; 13, mid-leaf cells; 14, section of margin at middle of leaf (×250); 15, gemmae (×420); 16, capsule (×15). 17, leaf of plant resembling D. subandreaeoides. Leaves ×40, apices ×70, cells ×420.

58 Didymodon

319

GB9, IR1∗ . Circumpolar Boreo-arctic Montane. Europe north to Svalbard, Caucasus, Siberia, Kamchatka, Kashmir, N. America. Although in the past in the British Isles D. icmadophilus has been separated from D. acutus by its slender habit and longly excurrent costa, apparently the only reliable characters are cell shape and papillosity and the nature of the annulus. The latter charter is of little use as D. acutus very rarely produces sporophytes in the British Isles and only five gatherings of D. icmadophilus with sporophytes have ever been seen from elsewhere.

3 D. rigidulus Hedw., Sp. Musc. Frond., 1801 Barbula rigidula (Hedw.) Mitt.

(Fig. 96)

Dense dark green to yellowish green cushions, mostly 3–10 mm high. Leaves appressed, flexuose, sometimes slightly twisted when dry, patent when moist, lanceolate to narrowly lanceolate, gradually tapering to stout, blunt apex; margins recurved or plane below, entire; costa ending below apex to shortly excurrent, adaxial cells ± hexagonal; cells in lower part of leaf rectangular, above quadrate-hexagonal, incrassate, sometimes strongly so, slightly papillose, pellucid, bistratose at margins above, 8–10 μm wide in mid-leaf. Globose, several-celled gemmae, 25–80 μm diameter, present in axils of upper leaves. Setae orange-red; capsules ellipsoid to cylindrical; lid longly rostrate, oblique; peristome teeth short, 320–480 μm long, filiform, ± straight; spores 10–12 μm. Capsules occasional, autumn to spring. n = 13∗ . On basic rocks, walls, old buildings, concrete, in situations where there is usually some shelter. 0–750 m. Common except in E. Anglia and N. E. England, rare to common in Scotland, occasional in Ireland. 112, H37, C. GB1078 + 116∗ , IR123 + 22∗ , C1. Circumpolar Boreo-temperate. Europe north to Fennoscandia, Turkey, Cyprus, Caucasus, Asia, Canary Islands, Africa, N. and C. America, Antarctica. The axillary gemmae always seem to be present though sometimes sparsely so. These and the bluntly pointed leaves will distinguish this plant from other Didymodon species. A plant from Snowdon (Fig. 96, 17), originally identified as Grimmia andreaeoides Limpr. was later thought by E. F. Warburg & E. W. Jones (Trans. Brit. Bryol. Soc. 1, 367–8, 1950) to be a montane form of D. rigidulus – they did not suggest that the two taxa were synonymous. The correct name of G. andreaeoides is Didymodon subandreaeoides (Kindb.) R. H. Zander and ¨ is a good species (J. Kuˇcera & H. Kockinger, J. Bryol. 22, 49–54, 2000). The two authors considered that the Snowdon specimen that they examined was too depauperate to allocate it to either D. rigidulus or D. subandreaeoides. The leaf morphology, areolation and presence of filiform shoots in the Snowdon material that I have seen are identical with those of D. subandreaeoides. However, the plants have abundant gemmae like those of D. rigidulus, unknown in D. subandreaeoides, so its identity is open to question.

4 D. mamillosus (Crundw.) M. O. Hill, J. Bryol., 1981 Barbula mamillosa Crundw.

(Fig. 97)

Dioicous. Dense compact green and brown tufts, 4–8 mm high, stems frequently branched. Leaves appressed, scarcely altered and not at all crisped when dry, erectspreading when moist, 0.5–1.2 mm long, ovate to lanceolate, channelled, tapering

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Fig. 97 1–5, Didymodon nicholsonii: 1, leaf; 2, leaf apex (×70); 3, basal cells; 4, mid-leaf cells; 5, section of margin at middle of leaf. 6–10, D. glaucus: 6, leaf; 7, leaf apex (×100); 8, basal cells; 9, mid-leaf cells; 10, gemmae (×420). 11–16, D. mamillosus: 11a, b, dry and moist shoots (×10); 12, leaves; 13, basal cells; 14, mid-leaf cells; 15, adaxial cells of costa at middle of leaf; 16, gemmae (×250). Leaves ×40, cells ×420.

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to acute, not or only slightly acuminate apex; margins narrowly recurved above; costa ending shortly below apex or percurrent, lamina cells continuous over adaxial surface except in lower part of leaf; basal cells quadrate to shortly rectangular, cells above quadrate or oblate, 8–10 μm wide, incrassate with round or oval lumens, mamillosely protuberant, obscurely papillose, marginal cells bistratose above. Brown spherical or ovoid gemmae, 30–45 m diameter, abundant in axils of upper !eaves. Only male plants known. on calcareous crags. 600 m. W. and Mid Perth. 2. GB2. Germany, Iceland, Portugal. Close to and possibly synonymous with D. rigidula, but differing in its smaller size, the leaves relatively wider with less regularly recurved margins, straighter and more closely appressed when dry, and in the mamillose cells. For an account of the species see A. C. Crundwell, J. Bryol. 9, 163–6, 1976.

5 D. nicholsonii Culm., Rev. Bryol., 1907 (Fig. 97) Barbula nicholsonii Culm., D. luridus var. nicholsonii (Culm.) Loeske, D. vinealis var. nicholsonii (Culm.) R. H. Zander Dark green tufts or patches, often coated with alluvial detritus, mostly 5–20 mm high. Leaves flexuose or appressed and straight when dry, patent, soft when moist, ovate to ovate-lanceolate, tapering to acute to obtuse, sometimes ± cucullate apex; margins recurved below, entire; costa ending below apex, adaxial cells quadratehexagonal; basal cells shortly rectangular, cells above quadrate-hexagonal, slightly incrassate, papillose, pellucid, bistratose at margins above, 6–8 μm wide in midleaf. Setae orange-red; capsules cylindrical; lid rostrate; peristome imperfect, teeth c. 800 μm long, filiform, straight when dry; spores 8–15 μm. Capsules very rare, spring. n = 13∗ . On rocks, exposed roots, walls and concrete below flood level of streams and rivers, occasionally on gravel, tarmac or concrete paths. Lowland. Rare but sometimes locally frequent, from Cornwall east to W. Sussex and Surrey, north to Roxburgh, Berwick and Arran, N. Kerry, E. Cork, Wexford, Offaly, Leitrim, Fermanagh. 46, H6. GB378 + 15∗ , IR5 + 1∗ . Suboceanic Temperate. Belgium, France, Germany, the Netherlands, Portugal, Spain, Turkey, California. Distinct from D. rigidulus in the wider leaves and smaller cells. The taxonomic position and status of D. nicholsonii has been a matter of some doubt as is evidenced by the synonymy. Its treatment as a variety of other Didymodon species is probably a reflection of the lack of familiarity with the plant by the authors concerned as on morphological grounds it is distinct. S.E.M. studies of leaf surfaces (A. J. E. Smith, unpublished) indicate that it is not related either to D. rigidulus or to D. vinealis. Sporophytes have only been seen once (M. F. V. Corley et al., J. Bryol. 14, 653–57, 1987). With regard to gemmae in D. nicholsonii, Dixon & Jameson (1924) say ‘Axillary gemmae occur, but apparently not so constantly as in B. rigidula’. I have not seen gemmae in British material and T. L. Blockeel (in M. O. Hill et al., 1992) suggests the reports are open to question. However, I have seen axillary gemmae similar to those of D. rigidulus in Belgian and German material of D nicholsonii. This suggests that reports of gemmae in British material are likely to be correct. T. Arts (Bull. Soc. R. Belg.

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120, 3–6), in addition to describing axillary gemmae, also reports the presence of rhizoidal gemmae in D. nicholsonii. A plant closely related to but distinct from D. nicholsonii was found on a concrete ride in Harewood Forest, near Andover, N. Hampshire, in 1985 and 1993. The plant is diploid (the only known example of diploidy in Didymodon) and should probably be treated as distinct species. However, until it is found elsewhere this is not advisable on the grounds of the considerable variability found within some Didymodon species. A description of the Harewood forest plant is as follows: Sex unknown. Dull green tufts, 7–10 mm high. Leaves erect, appressed, straight when dry, erect-patent when moist, lanceolate, tapering from near base to obtuse apex; margins usually recurved from near base to c. 3 /4 way up leaf, papillose-crenulate above; costa stout, ending below apex, adaxial cells quadrate; cells incrassate, strongly papillose except near base, at extreme base rectangular, cells above irregular in shape, shortly rectangular, irregularly quadrate to wider than long, in longitudinal rows, becoming ± quadrate-hexagonal and irregularly arranged in upper part of leaf, very opaque, bistratose at margins, 8–10 μm wide in mid-leaf. Vegetative propagules, gametangia and sporophytes unknown. n = 26∗ (Fig. 98).

6 D. glaucus Ryan, Rev. Bryol., 1901 (Fig. 97) ¨ Barbula glauca (Ryan) H. Moller, D. rigidulus var. glaucus (Ryan) Wijk & Margad. Plants very small, in bright green patches, 1–3 mm high. Leaves incurved when dry, patent to recurved from erect basal part when moist, ligulate-lanceolate, tapering to long acute to acuminate apex; margins plane or variously recurved, sometimes obscurely denticulate near base, ± crenulate above; costa ending below apex, adaxial cells quadrate; basal cells rectangular, hyaline, cells above hexagonal, thin-walled, papillose, pellucid, unistratose at margins, 6–10 μm wide in mid-leaf. Chains of brown, spherical, 1–3-celled axillary gemmae, 13–25 μm diameter, often produced. Only female plants known in Britain. Capsules unknown. In crevices of chalk and limestone and on chalk soil. Lowland. Very rare and endangered, S. Wiltshire, W. Sussex (1915), N. W. Yorkshire (1914). 3. GB1 + 2∗ . European Temperate. Austria, Czechoslovakia, Germany, Greece, Hungary, Italy, Luxembourg, Norway, Romania, Sweden, Switzerland, Turkey. There has been confusion between D. glaucus and D. australasiae var. umbrosus but the latter differs in the expanded leaf bases with narrow marginal cells and the plane crenulate margins. This species is regarded as critically endangered in the Red List of British Mosses and is a protected species under the Wildlife and Countryside Act.

¨ Hal.) 7 D. australasiae (Hook. & Grev.) R. H. Zander var. umbrosus (Mull. R. H. Zander (Fig. 98) ¨ Hal.) R. H. Zander, Trichostomopsis umbrosus (Mull. ¨ Hal.) D. umbrosus (Mull. H. Rob. Pale green patches, often encrusted with calcareous matter, 2–10 mm high. Leaves spreading, flexuose or somewhat curled when dry, spreading from erect basal part when moist, lower small, upper longer, from expanded basal part narrowly

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Fig. 98 1–9, Didymodon nicholsonii (diploid form): 1, 2, moist and dry shoots (×10); 3, leaves (×30); 4, axillary hair (×250); 5, section of leaf margin; 6, adaxial cells of costa; 7, basal cells; 8, mid-leaf cells; 9, leaf apex. 10–13, D. australasiae var. umbrosus: 10, leaves (×40); 11, leaf apex (×100); 12, basal cells; 13, mid-leaf cells; 14, rhizoidal gemmae (from A. C. Crundwell & H. L. K. Whitehouse, J. Bryol. 10, 5–8. Cells ×420.

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linear-lanceolate, acute or occasionally obtuse; margins plane, crenulate; costa thin, percurrent, adaxial cells rectangular; basal cells rectangular, hyaline, very narrow near margins, cells above hexagonal, often wider than long, thin-walled, mamillose, opaque, bistratose at margins from near base to bistratose apex, 8–12 μm wide in mid-leaf. Brown irregularly shaped rhizoidal gemmae, 25–200 μm wide, abundant. Only female plants known in the British Isles. On damp mortar at the base of walls, in chalk and limestone quarries, on banks by springs, in shady situations. Lowland. Occasional in England from W. Cornwall and N. Somerset east to Sussex and north to W. Yorkshire, Glamorgan, Dublin. 35, H1. GB43, IR1. Oceanic-temperate. Czech Republic, Germany, Portugal, Spain, Canary Islands, Morocco, Tunisia, California, Mexico, Uruguay, Argentina. Originally thought to be an introduction but probably native. Likely to have been overlooked in the past because of its small size, and its recent apparent spread could be due to increasing familiarity with the species and the habitat in which it grows. That it has been found in natural habitats also supports the suggestion that it is native. For an account of this plant in Britain see A. C. Crundwell & H. L. K. Whitehouse, J. Bryol. 10, 5–8, 1978.

Section Vineales (Steere) R. H. Zander, Bryologist, 1978 Leaves spreading when moist, keeled or concave; margins weakly recurved to revolute; costa percurrent to shortly excurrent, adaxial cells quadrate in upper half of leaf, in section with adaxial stereid band lacking; cells unistratose above or occasionally bistratose at margins, smooth or papillose. Peristome absent to well developed and spirally coiled. 8 D. vinealis (Brid.) R. H. Zander, Phytologia, 1978 Barbula vinealis Brid.

(Fig. 99)

Dense olive green tufts, mostly 5–20 mm high. Leaves erect, flexuose, slightly twisted when dry, erect-patent, not flexuose when moist, upper 1–3 mm long, lanceolate to narrowly lanceolate, tapering to acute apex; margins narrowly recurved to above middle; costa ending in or below apex, adaxial cells quadratehexagonal; basal cells quadrate to shortly rectangular, cells above irregularly quadrate, relatively thin-walled, papillose, opaque, unistratose at margins, 6–10 μm wide in mid-leaf, apex ending in a single smooth pellucid cell. Setae red below, orange above; capsules narrowly ellipsoid to ellipsoid; lid oblique, longly rostrate; peristome teeth filiform, spirally coiled, c. 500–600 μm long; spores c. 10 μm. Capsules rare, spring to autumn. n = 14. In dry open situations on basic rocks, walls, old buildings, concrete, hard calcareous soil, sand-dunes. Frequent or common in the southern part of Britain, rare in the north, extending to Shetland, rare in Ireland. 83, H20, C. GB539 + 88∗ , IR12 + 8∗ , C2. European Southern-temperate. Europe north to Scandinavia, Iceland, Turkey, Cyprus, Caucasus, Nepal, China, Macaronesia, N. Africa, N. America, Mexico, Jamaica. Recognised in the field by the dense olive green cushions and the leaves erect, rigid and twisted with almost bristly points when dry.

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The record of D. reedii H. Rob. from Britain, reported by J. Appleyard (J. Bryol. 14, 319– 321, 1985) is based upon a form of D. vinealis (see T. L. Blockeel & A. J. E. Smith, J. Bryol. 20, 65–68, 1998).

9 D. insulanus (De Not.) M. O. Hill, J. Bryol., 1981 (Fig. 99) Barbula cylindrica (Taylor) Schimp., B. vinealis ssp. cylindrica (Taylor) Podp., D. vinealis var. flaccidus (Bruch & Schimp.) R. H. Zander Lax olive green to brownish green tufts or patches, mostly 5–50 mm high. Upper and sometimes lower leaves crisped when dry, patent, flexuose and sometimes undulate when moist, upper leaves 2–5(−7) mm long, linear-lanceolate, very longly tapering to acute or acuminate apex; margins recurved to about the middle; costa ending below apex to excurrent, adaxial cells quadrate-hexagonal; basal cells quadrate to shortly rectangular, cells above irregularly quadrate-hexagonal, papillose, opaque, unistratose at margins, 6–10 μm wide in mid-leaf, apex ending in a single smooth hyaline cell. Setae red below, orange above; capsules cylindrical; lid longly rostrate, oblique; peristome teeth filiform, spirally coiled, 500– 600 μm long; spores c. 10 μm. Capsules very rare, spring, summer. On usually base-rich damp rocks, cliff ledges, sheltered walls and wall bases, tree boles and roots by streams and rivers, on soil. 0–430 m. Occasional in N. Scotland, frequent or common elsewhere, frequent in Ireland. 112, H37, C. GB1368 + 85∗ , IR186 + 6∗ , C3. Eurasian Southern-temperate. Europe north to Fennoscandia, Faeroes, Iceland, Turkey, Cyprus, Caucasus, Tibet, China, Macaronesia, N. Africa, N. and C. America. D. insulanus differs from D. vinealis in the laxer tufts and the longer more tapering leaves which are crisped when dry. There is also apparently a difference in capsule shape, but as capsules are only rarely produced it is uncertain how constant this is. Occasional intermediates between the two species occur and there is some difference of opinion as to whether D. insulanus should be treated as a species or as a variety of D. vinealis. Dark brown rhizoidal gemmae, 87–135 × 65–92 μm, have been reported from D. insulanus by L. T. Ellis & A. C. Smith (J. Bryol. 12, 509–10, 1993), but they appear to be extremely rare.

10 D. luridus Hornsch. ex Spreng., Syst. Veg., 1827 (Fig. 99) Barbula lurida (Hornsch. ex Spreng.) Lindb., B. trifaria (Hedw.) Mitt., D. ¨ trifarius (Hedw.) Rohl., D. vinealis var. luridus (Hornsch. ex Spreng.) R. H. Zander Dark green to brownish tufts or patches, 5–30 mm high. Leaves imbricate, not shrunken when dry, patent when moist, concave, ovate-lanceolate to broadly ovate, apex rounded to acute, base slightly decurrent; margins recurved below, entire; costa stout, 40–60(−80) μm wide near base, ending in or below apex, adaxial cells ± hexagonal; cells at extreme base shortly rectangular, elsewhere ± hexagonal, incrassate, smooth, pellucid, unistratose at margins, 6–10 μm wide in mid-leaf. Setae purplish; capsules ellipsoid to subcylindrical; lid obliquely rostrate;

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Fig. 99 1–7, Didymodon vinealis: 1, dry shoot (×10); 2, leaves (×25); 3, leaf apex (×70); 4, adaxial side of costa at middle of leaf: 5, basal cells; 6, mid-leaf cells; 7, capsule (×15). 8–9, D. insulanus: 8, dry shoot (×10); 9, leaf (×25). 10–15, D. luridus: 10, leaves (×40); 11, leaf apex (×70); 12, adaxial side of costa at middle of leaf; 13, basal cells; 14, mid-leaf cells; 15, capsule (×15). Cells ×420.

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peristome teeth short, c. 100 μm long, straight; spores 12–16 μm. On calcareous rocks, stones, wall bases, old buildings, thin soil, rarely on tree roots by rivers, usually but not necessarily in moist situations. Lowland. Common in the southern half of England, occasional elsewhere in England, Wales and S. Scotland, very rare in N. Scotland, Banff, Arran, Shetland, rare in Ireland. 81, H20, C. GB523 + 84∗ , IR8 + 14∗ , C1 + 4∗ . Submediterranean-Subatlantic. Europe north to S. Scandinavia, Turkey, Cyprus, Caucasus, W. Asia, Macaronesia, N. Africa, western N. America. Recognised by the broad leaves, appressed but otherwise hardly altered when dry. Sometimes confused with D. tophaceus but differing in the leaves imbricate when dry, leaf shape, the ± hexagonal adaxial cells of the costa and the smooth lamina cells. D. cordatus has a wider costa and axillary gemmae.

11 D. cordatus Jur., Bot. Zeit., 1866 Barbula cordata (Jur.) Braithw.

(Fig. 100)

Dark green or brownish green tufts or patches, c. 10 mm high. Leaves slightly incurved and narrowed when dry, patent when moist, concave, broadly ovate, tapering to acute apex (in British plants); margins strongly recurved, entire; costa very stout, 70–100 μm wide near base, excurrent, adaxial cells ± hexagonal; basal cells rectangular, cells above quadrate-hexagonal, slightly incrassate, smooth, pellucid, unistratose at margins, 6–8 μm wide in mid-leaf. Numerous spherical several-celled gemmae, c. 30 μm diameter, in axils of upper leaves. Only female plants known in Britain. On soil on a sea-cliff and a rock outcrop. Lowland. Very rare and endangered, N. Devon. 1. GB1. European Southern-temperate. Europe north to Belgium and Germany, east to the Crimea, Caucasus, Turkey. This species is treated as vulnerable in the Red List of British Mosses and is protected under the Wildlife and Countryside Act.

12 D. sinuosus (Mitt.) Delogne, Bull. Soc. Roy. Bot. Belgique, 1873 (Fig. 100) Barbula sinuosa (Mitt.) Gravet, Oxystegus sinuosus (Mitt.) Hilp., Trichostomum ¨ Hal. sinuosum (Mitt.) Mull. Green tufts or patches, to 20 mm high. Leaves curled when dry, patent, flexuose when moist, fragile, from slightly expanded basal part linear-lanceolate, tapering to narrowly lingulate to subulate fragile obtuse apical part; margins plane or narrowly recurved below, undulate, crenulate, sinuose and often notched and/or irregularly toothed above; costa ending below apex, adaxial cells quadrate; basal cells rectangular, cells above ± quadrate-hexagonal, incrassate, papillose, opaque, unistratose at margins, 6–8 μm wide in mid-leaf. Only female plants known in the British Isles; capsules unknown. On damp shaded usually basic rocks by streams and rivers and in sheltered habitats on walls and old buildings, among tree roots in woodland. Lowland. Common in the southern half of England, frequent in N. W. Wales, Lancashire, western Yorkshire, very rare in Scotland, extending

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Fig. 100 1–6, Didymodon cordatus: 1, leaf (×40); 2, leaf apex; 3, basal cells; 4, mid-leaf cells; 5, gemmae (×250). 6–9, D. sinuosus: 6, leaves (×25); 7, leaf apex; 8, basal cells; 9, mid-leaf cells. 10–15, D. tophaceus: 10, leaves (×30); 11, adaxial side of costa at middle of leaf; 12, basal cells; 13, mid-leaf cells from broad-leaved plant; 14, mid-leaf cells from narrow-leaved plant; 15, capsule (×15). Apices ×70, cells ×420.

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north to Shetland, occasional in Ireland. 76, H27, C. GB477 + 58∗ , IR33 + 8∗ , C1. Submediterranean-Subatlantic. Europe north to Sweden, Turkey, Caucasus, Alaska. The caducous leaf tips probably act as vegetative propagules. The plant from Roscommon, resembling Oxystegus obtusifolius Hilp., mentioned in the first edition of this book, has been shown to be a form of D. sinuosus (see M. O. Hill & H. L. K. Whitehouse, J. Bryol. 14, 594–5, 1987).

Section Fallaces (De Not.) R. H. Zander, Bryologist, 1977 Leaves spreading to strongly recurved when moist; margins plane to recurved; costa ending below apex to shortly excurrent, adaxial cells shortly rectangular to elongate, in section adaxial stereid band usually present; lamina cells papillose or not. Peristome rudimentary or well developed and spirally coiled. 13 D. tophaceus (Brid.) Lisa, Elenco Muschi Torino, 1837 Barbula tophacea (Brid.) Mitt.

(Fig. 100)

Olive green to brownish tufts or patches, 5–50 mm high. Leaves erect, flexuose to slightly incurved, shrunken or not when dry, ± patent when moist, concave or not, from broadly ovate to lanceolate basal part ± lingulate and hardly tapering, apex rounded to obtuse or shortly acute; margins narrowly recurved, entire; costa ending below apex, adaxial cells elongate; cells usually incrassate, basal rectangular, cells above irregular, hexagonal to rhomboidal in narrow-leaved forms to ± regularly quadrate in broad-leaved forms, slightly papillose, pellucid, unistratose at margins, 10–12 μm wide in mid-leaf. Brown uniseriate 2–6-celled gemmae, 25–74 μm long, occasionally produced in leaf axils and on rhizoids. Setae deep red; capsules ellipsoid; lid obliquely rostrate, long or short; peristome short, c. 250 μm long; spores 12–16 μm. On sheltered, base-rich and especially damp or wet rocks, stones, walls in woods, on cliffs, coastal undercliffs, stream banks, flushes, on tracks and soil, often lime-encrusted and forming tufa in calcareous habitats. 0–440 m. Occasional in Scotland and Ireland, frequent or common and sometimes locally abundant elsewhere. 111, H29, C. GB850 + 115∗ , IR74 + 4∗ , C3. European Southern-temperate. Europe north to Svalbard, Faeroes, Iceland, Turkey, Cyprus, Caucasus, Asia, Canary Islands, Africa, N. America, Mexico, Bolivia. A very variable species for which a number of varieties of no value have been described. Usually easily recognised when growing in moist base-rich habitats by the olive-green to brownish colour and the leaves hardly tapering to usually obtuse or rounded apices.

14 D. spadiceus (Mitt.) Limpr., Laubm. Deutschl., 1888 Barbula spadicea (Mitt.) Braithw.

(Fig. 101)

Greenish brown tufts, mostly 10–30 mm high. Leaves erect, flexuose, ± twisted when dry, erect-patent when moist, (1.6−)1.8– 4.0 mm long, from ovate to lanceolate basal part tapering to acute to obtuse apex; margins recurved below, papillosecrenulate above; costa stout, ending below apex, adaxial cells elongate; extreme

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Fig. 101 1–5, Didymodon spadiceus: 1, leaves (×25); 2, leaf apex (×70); 3, basal cells; 4, mid-leaf cells; 5, capsule (×15). 6–8, D. maximus: 6, leaf (×17.5); 7, basal cells; 8, mid-leaf cells. 9–12, D. tomaculosus: 9, leaves (×75); 10, basal cells; 11, mid-leaf cells; 12, rhizoidal gemmae (×500). Cells ×420.

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basal cells rectangular to narrowly rectangular, above irregularly hexagonal, incrassate, papillose, pellucid, unistratose at margins, 8–10(−12) μm wide in midleaf. Setae deep red below, paler above; capsules ellipsoid to cylindrical, straight or slightly curved; lid oblique, longly rostrate; peristome teeth short, c. 500 μm long, filiform, ± straight; spores 10–16 μm. Capsules occasional, autumn. On baserich rocks and on tree boles by fast-flowing streams and rivers, often embedded in alluvial detritus, in seepage areas in ravines. 0–550 m. Rare to occasional in W. and N. Britain, very rare elsewhere, E. Sussex, W. Kent, rare in Ireland. 58, H21. GB138 + 67∗ , LR13 + 14∗ . European Temperate. Europe north to Scandinavia, Cyprus, Caucasus, N. Asia, N. America, Greenland. Close to D. fallax but usually a larger plant, lacking a reddish tinge, with longer leaves which are erect-patent rather than spreading or recurved when moist and less well developed peristome with straight teeth.

15 D. fallax (Hedw.) R. H. Zander, Phytologia, 1979 Barbula fallax Hedw.

(Fig. 102)

Dull green to brownish green, often tinged with red, loose tufts or patches or scattered plants, to 15(−30) mm high. Leaves distant, erect, flexuose, twisted when dry, erect-patent to spreading or frequently recurved when moist, 1.2–2.4 mm long, from broad base lanceolate to narrowly lanceolate, tapering to acute apex, keeled above, often with a plica on either side of the costa towards base; margins recurved at least below, entire to papillose-crenulate above; costa stout, reddish brown, ending below apex to percurrent, adaxial cells elongate; basal cells rectangular, cells above irregularly hexagonal with rounded lumens, weakly to strongly papillose, pellucid, unistratose at margins, 8–12 μm wide in mid-leaf. Setae reddish brown; capsules ellipsoid to narrowly ellipsoid, straight or slightly curved; peristome teeth 1.0–1.5 mm long, filiform, spirally coiled; spores 12–16 μm. Capsules occasional, winter, spring. n = 13. In open base-rich sites on soil or clay, in fields, by ditches and streams, on sand-dunes. 0–490 m. Occasional in N. W. Scotland, frequent or common elsewhere, frequent in Ireland. 111, H39, C. GB1323 + 98∗ , IR211 + 5∗ , C2. Circumpolar Southern-temperate. Europe north to Fennoscandia, Faeroes, Iceland, Turkey, Cyprus, Caucasus, Asia, La Palma, Madeira, N. Africa, N. America, Greenland. A variable species usually recognisable in the field by its reddish-tinged shoots and spreading to recurved leaves. Papillosity of the leaves varies greatly, ranging from faint to very strong; similarly with the margins which range from entire to papillose-crenulate.

16 D. tomaculosus (Blockeel) M. F. V. Corley, J. Bryol., ’981 Barbula tomaculosa Blockeel

(Fig. 101)

Small, dark green patches or scattered plants, c. 6 mm high. Leaves erect to curved when dry, erect-patent, patent or occasionally squarrose when moist, ovate or ovate-lanceolate, acuminate; margins recurved, entire; costa percurrent to shortly

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Fig. 102 1–6. Didymodon fallax: 1, leaves (×40); 2, leaf apex (×100); 3, basal cells; 4, mid-leaf cells; 5, adaxial cells of costa at middle of leaf; 6, capsule and lid (×15). 7–10, D. ferrugineus: 7, shoot (×15); 8, leaf (×40); 9, basal cells; 10, mid-leaf cells. Cells ×420.

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excurrent, adaxial cells elongate; basal cells quadrate to rectangular, cells above longer than wide to wider than long, somewhat mamillose, pellucid, unistratose at margins, 8–14 μm wide in mid-leaf. Brownish sausage-shaped rhizoidal gemmae consisting of a single row of cells, 40–140 μm long, usually abundant. Only female plants known. On moist disturbed ground in open situations on usually heavy clay soil. Lowland. Very rare, Derby, S. W. and M. W. Yorkshire, Offaly, Kildare. 3, H2. GB6, IR2. Endemic (Suboceanic Temperate). Likely to be overlooked because of its small size and the frequently scattered plants. Readily distinguished microscopically by the sausage-shaped rhizoidal gemmae. For an account of this plant see T. L. Blockeel, J. Bryol. 11, 585–9, 1981.

17 D. ferrugineus (Schimp. & Besch.) M. O. Hill, J. Bryol., 1981 Barbula recurvifolia Schimp., B. reflexa (Brid.) Brid.

(Fig. 102)

Lax reddish brown tufts or patches, to 25 mm high. Leaves erect, flexuose when dry, squarrose when moist, keeled above, ovate-lanceolate, tapering to acute apex; margins recurved below, papillose-crenulate; costa ending below apex, adaxial cells elongate; basal cells shortly rectangular, cells above hexagonal, incrassate, papillose with tall papillae, pellucid, unistratose at margins, lumens rounded, 6–10 μm wide in mid-leaf. Capsules ellipsoid; peristome teeth ± straight, c. 600 μm long. Capsules unknown in the British Isles. In open or slightly shaded base-rich situations on rock, in scree, on thin soil, sand-dunes and in chalk-pits. 0–785 m. Rare to occasional but sometimes locally abundant, from Cornwall east to Kent and north to Orkney, occasional in Ireland. 65, H23. GB124 + 29∗ , IR45 + 8∗ . European Boreo-temperate. N. and C. Europe, Turkey, Caucasus, Siberia, Himalayas, China, N. America. Sometimes difficult to separate from forms of D. fallax with strongly recurved leaves, but distinguishable on the basis of a combination of characters: reddish-brown coloration, strongly squarrose more shortly pointed leaves and cells with tall papillae.

18 D. maximus (Syed & Crundw.) M. O. Hill, J. Bryol., 1981 Barbula maxima Syed & Crundw., B. reflexa var. robusta Braithw.

(Fig. 101)

Tall yellowish brown to brown tufts, 2–8 cm high. Leaves strongly flexuose when dry, strongly recurved when moist, 2–4 mm long, lanceolate from broad basal part, gradually tapering to acute apex; margins recurved, papillose-crenulate; costa ending in apex, adaxial cells elongate; cells incrassate, basal narrowly rectangular, cells above irregularly hexagonal with ± angular lumens, papillose, pellucid; margins unistratose, 10–12 μm wide in mid-leaf. Gametangia and sporophytes unknown. On damp ledges or soil on limestone cliffs. 300 m. Very rare but locally common. Sligo, Leitrim. H2. IR5. Hyperoceanic Temperate. Canada (?). Specifically distinct from D. ferrugineus in its larger size, and narrower and more longly tapering leaves with angular cell lumens (see H. Syed & A. C. Crundwell, J. Bryol., 7, 527– 9, 1973).

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There are two specimens of a somewhat similar looking species, D. asperifolius (Mitt.) H. A. Crum et al. (Barbula asperifolia Mitt., B. rufa (Lor.) Jur.), collected by J. Stirton apparently from Ben Lawers in 1867. There is some doubt as to the authenticity of the locality (see A. C. Crundwell, Trans. Brit. Bryol. Soc. 3, 174–9, 1957).

59 SCOPELOPHILA (MITT.) LINDB., ACTA SOC. SCI. FENN., 1872 Dioicous. Plants forming turfs. Stems without central strand. Axillary hairs 3–5 cells long, basal cell usually brownish. Leaves incurved to spreading, contorted when dry, spreading when moist, lingulate to ligulate or lanceolate, acute to obtuse; margins plane or recurved below, entire, crenulate or denticulate above; costa ending below apex to percurrent, 2–4 cells wide on adaxial side, cells quadrate to rectangular, in section with one stereid band; basal cells rectangular, cells above rounded-quadrate or hexagonal, smooth. Perichaetial leaves similar to stem leaves. Capsules ellipsoid to shortly cylindrical, gymnostomous; lid rostrate; calyptrae cucullate. Three species of substrates containing heavy-metals, distributed through Europe, Asia, C. Africa, N. and S. America, Hawaii. Derivation: referring to the rocky or stony habitat.

1 S. cataractae (Mitt.) Broth., Nat. Pflanzenfam., 1902 (Fig. 103) Dense tufts or patches, sometimes extensive, dull olive-green to glossy green above, reddish brown below, to 5 cm high. Leaves curved when dry, erect-patent to patent when moist, lower narrowly lanceolate, upper ± lingulate, widest at or above middle, abruptly tapering to acute apex, strongly channelled above; margins plane or recurved below, entire; costa percurrent or slightly excurrent, adaxial cells rectangular; basal cells rectangular, decreasing in size from costa to margins, cells above irregularly quadrate to hexagonal or wider than long, incrassate, smooth, 6–10(−12) μm wide in mid-leaf. Protonemal gemmae, 50–100 μm long, 1–6 cells long, sometimes present. Only male plants known in Europe. n = 13∗ . Heavymetal mine heaps and waste, Lowland. Very rare, Cornwall, S. Devon, Glamorgan, Cardigan, Caernarfon, I. of Man. 7. GB7. Circumpolar Southern-temperate. Belgium, France, Germany, Italy, the Netherlands, Spain, tropical Asia, Korea, Japan, N. Carolina, Arizona, C. America. Rhizoidal gemmae have been reported from material from Belgium, France and the Netherlands. The gemmae are pale brown, very irregular in shape and size, 50–400 × 20–150 μm (see T. Arts, Lindbergia 14, 59–62, 1988). For accounts of S. cataractae in England and Wales see M. F. V. Corley & A. R. Perry, J. Bryol. 13, 323–8, 1985, A. C. Crundwell, J. Bryol. 14, 387, 1986 and F. Rumsey & M. E. Newton, J. Bryol. 15, 519–24, 1989. Known from an old metal mine in S. Devon, zinc waste in Glamorgan and lead-spoil in Cornwall, Cardigan, Caernarfon and the Isle of Man. Some authorities consider this species to be introduced in Europe, having been brought in with ore. However, as it also occurs on spoil from mines to which ore would not have been introduced this seems unlikely.

60 Stegonia

335

Fig. 103 Scopelophila cataractae: 1, leaves (×60); 2, basal cells (×280); 3, mid-leaf cells (×420).

Subfamily 3 Pottioideae Stems with sclerodermis poorly differentiated from central strand. Leaves usually lingulate to spathulate, more rarely narrowly lanceolate to elliptical, basal part often expanded and hyaline; costa usually with only one stereid band; cells in upper part usually bulging on adaxial side, and weakly convex on abaxial side. Clavate axillary gemmae rare. In British genera laminal KOH reaction either yellow or red. Tribe 1 Hyophileae Leaf cells bulging on adaxial side, ± flat on abaxial side or if cells not bulging on adaxial side then only one stereid band present in costa section.

60 STEGONIA VENTURI., REV. BRYOL., 1883 Autoicous. Stems with central strand; sclerodermis and hyalodermis lacking. Axillary hairs 3–6 cells long. Leaves imbricate, broadly ovate or elliptical, strongly concave; costa percurrent to excurrent in hyaline point, 3–4 cells wide on adaxial side, cells shortly rectangular, in section with abaxial stereid band; basal cells rectangular, cells above smooth, hexagonal, in upper 1 /4 –1 /3 of leaf usually hyaline,

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thick-walled. Capsules cleistocarpous and immersed or dehiscent and exserted, peristome absent, imperfect or well developed; calyptrae cucullate. Laminal KOH reaction red. Three Northern Hemisphere species. Derivation: from the Greek, meaning to cover closely, a reference to the strongly concave leaves. The genus as defined above by Zander (1993) is unnatural, containing one species with immersed cleistocarpous capsules and two with exserted dehiscent capsules.

¨ 1 S. latifolia (Schwagr.) Venturi ex Broth., Laubm. Fennoskand., 1923 (Fig. 104) ¨ ¨ Hal. Pottia latifolia (Schwagr.) Mull. Small pale green patches or clusters of bud-like short-lived plants, c. 2 mm high. Leaves imbricate when moist, hardly altered when dry, very strongly concave, obovate to broadly obovate-spathulate, apices obtuse or rounded; margins plane, faintly denticulate above; costa weak, ending below apex; cells in lower part of leaf narrowly rectangular, hyaline, becoming smaller, rectangular to irregularly rhomboidal above, smooth, 8–16 μm wide in widest part of leaf, smaller and more incrassate towards margins and apex and sometimes colourless. Capsules narrowly ellipsoid, erect or nearly so; peristome well developed; spores 40–50 μm. Capsules common, summer, autumn. n = 26. On calcareous soil on rock ledges, amongst rocks and in crevices. C. 550 m. Very rare, E. Perth, S. Aberdeen, Banff, old records from Mid Perth and Angus. 5. GB6 + 3∗ . Circumpolar Arctic-montane. Montane and northern Europe north to Svalbard, Turkey, Asia, N. America, New Zealand (introduced), Antarctica. The very concave leaves with costa ending below the apex will distinguish this species from other British members of the Pottiaceae. Tortula leucostoma, with which it sometimes occurs, has acuminate leaves with strongly recurved margins.

¨ 61 PTERYGONEURUM JUR., LAUBM.-FL. OSTERR.-UNG., 1882 Autoicous. Stems with central strand, sclerodermis and hyalodermis absent. Axillary hairs c. 7 cells long. Leaves concave, ovate or obovate, obtuse or rounded; margins plane or narrowly recurved; costa excurrent in frequently hyaline hairpoint, expanded above with 2–4 chlorophyllous lamellae, c. 12 cells high, on adaxial surface, in section with abaxial stereid band; basal cells rectangular, cells above quadrate or wider than long, smooth or with small papillae. Perichaetial leaves not sheathing. Setae long or short, straight; capsules ± erect, symmetrical, ovoid to cylindrical; lid rostrate; peristome imperfect and spirally curved or absent. Twelve species distributed through Europe, N. and W. Asia, N. and southern Africa, N. America, southern S. America, Australia. Derivation: referring to the ‘wings’ on the adaxial side of the costa. ´ et al., Nova Hedwigia 61, For observations on the genus Pterygoneurum see J. S. Carrion 481–96, 1995.

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337

Fig. 104 1–4, Pterygoneurum ovatum: 1, leaves; 2, mid-leaf cells; 3, capsule; 4, cells of lid. 5–8, P. lamellatum: 5, leaves; 6, mid-leaf cells; 7, capsule; 8, cells of lid. 9–12, Stegonia latifolia: 9, leaves; 10, mid-leaf cells; 11, cells from near leaf apex; 12, old capsule. Leaves ×25, cells ×420, capsules ×15.

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Setae 2–3 mm long, capsules ovoid or ovate-ellipsoid, cells of lid in straight rows, spores papillose, 26–40 μm 1. P. ovatum Setae 3–6 mm long, capsules ellipsoid, cells of lid in spiral rows, spores smooth, 10–30 μm 2. P. lamellatum 1 P. ovatum (Hedw.) Dixon, Rev. Bryol. Lich´enol., 1934 Tortula pusilla Mitt.

(Fig. 104)

Small greenish or sometimes hoary patches, 1–2 mm high. Leaves imbricate when dry, ± imbricate or erect-patent when moist, very concave, ovate, obovate to obovate-spathulate, obtuse; margins ± plane, entire; costa excurrent in short to long (to 1 mm), often hyaline, slightly denticulate hair-point, stout, enlarged in upper part of leaf with 2–4 green lamellae on adaxial side; cells in lower part of leaf rectangular, hyaline, cells above quadrate-hexagonal, incrassate, slightly papillose, 10–18 μm wide in widest part of leaf, smaller towards margins and apex. Setae 2–3 mm long; capsules ovoid or ovate-ellipsoid, erect, straight, dark purplish brown, sulcate when dry and empty; lid obliquely rostrate with cells in straight rows; peristome lacking; spores papillose, 26–40 μm. Capsules common, autumn, winter. n = 26. On basic soil on banks, among rocks, in quarries, on cliffs and formerly on mud-capped walls. Lowland. Rare to occasional in calcareous areas of England, very rare in Wales and Scotland, extending north to E. Ross, old records from Mid Cork, and Down. 56, H2. GB52 + 88∗ , IR3∗ . Circumpolar Southerntemperate. Europe north to Scandinavia, Caucasus, Turkey, W. Asia, Algeria, Morocco, N. America, Tierra del Fuego, Australia. This and particularly the next species were once frequent on newly mud-capped calcareous walls, a habitat that is now almost completely lost.

¨ 2 P. lamellatum (Lindb.) Jur., Laubm.-Fl. Osterr.-Ung., 1882. Tortula lamellata Lindb.

(Fig. 104)

Plants 1–2 mm high. Leaves very similar to those of P. ovatum but hair-points not exceeding 400 μm long. Setae 3–6 mm long; capsules ellipsoid, erect, straight or slightly curved, brown; lid obliquely rostrate with cells in spiral rows; peristome poorly developed and falling with lid; spores very finely papillose, 10–30 μm. Capsules common, autumn, winter. n = 52. On calcareous soil and mud-capped limestone walls and in chalk pits. Lowland. Now probably extinct, recorded from scattered localities from S. Devon east to W. Kent and north to Yorkshire, Stirling, Dublin, Down, but seen recently only in W. Norfolk and Cambridge. 17, H2. GB2 + 26∗ , IR3∗ . Circumpolar Southern-temperate. Central and western Europe, Greece, Sicily, C. Asia, N. and C. America, Greenland. Very much decreased because of the destruction of the species’ main habitat, mudcapped walls. Only distinguished with certainty from P. ovatum by the cells of the capsule

62 Aloina

339

lid in spiral rows, although P. ovatum sometimes has longer leaf hair-points and larger spores.

62 ALOINA KINDB., BIH. KONGL. SVENSKA VETENSKT.-AKAD. HANDL., 1882 Dioicous or autoicous. Stems short, with or without central strand. Leaves rigid, thick, usually incurved when dry, erect to spreading when moist, from hyaline sheathing base, ovate to lingulate, concave, apex obtuse to rounded, cucullate; margins entire; costa broad, usually ending in or below apex, with chlorophyllous branched granulose filaments on adaxial surface in upper part, in section with abaxial stereid band; cells in sheathing base rectangular, hyaline, cells above quadrate or transversely oblong or elliptical. Setae straight; capsules erect or inclined, ellipsoid to cylindrical, straight or curved; annulus persistent or not; peristome with short basal membrane and 32 filiform spirally coiled teeth. Laminal KOH reaction yellow. A small world-wide genus of about 8 species. Derivation: alluding to the fleshy nature of the leaves. For a monograph of Aloina in the Mediterranean and neighbouring areas see M. T. Gallego et al., Nova Hedwigia 69, 173–94, 1999.

1 Marginal cells near leaf base elongate, hyaline, thin- walled, forming distinct border, annulus separating 2 Marginal cells near leaf base quadrate or rectangular, if hyaline then thick-walled, annulus persisting 3 2 Leaves mostly 2.0–3.5 times as long as wide, spores 18–22 μm 1. A. brevirostris Leaves mostly 4–6 times as long as wide, spores 10–16 μm 2. A. rigida 3 Basal membrane of peristome not projecting above mouth of capsule, spores 18–25 μm 3. A. aloides Basal membrane projecting above mouth of capsule, spores 12–16 μm 4. A. ambigua 1 A. brevirostris (Hook. & Grev.) Kindb., Bih. Kongl. Svenska Vetenskt.-Akad. Handl., 1883 (Fig. 105) Tortula brevirostris Hook. & Grev. Synoicous or sometimes male only. Greenish or brownish patches, 1–2 mm high. Leaves incurved when dry, erect to spreading when moist, very concave, lower leaves ± orbicular, upper broadly lingulate, 2.0–3.5 times as long as wide, hyaline basal part as long as or longer than blade, apex rounded or obtuse, cucullate; costa poorly defined, ending in apex, in section with 1–3 rows of guide cells and 1(−2) stereid bands; marginal cells near base elongate, thin-walled,

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Fig. 105 1–3, Aloina brevirostris: 1, leaves; 2, leaf section; 3, capsule. 4–6, A. rigida: 4, leaves; 5, capsule; 6, capsule mouth. 7–9, A. ambigua: 7, leaves; 8, capsule; 9, capsule mouth. 10–13, A. aloides: 10, leaves; 11, leaf section; 12, capsule; 13, capsule mouth. Leaves ×25, sections ×165, capsules ×10, capsule mouths ×70.

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341

hyaline. Capsules erect, narrowly ellipsoid, straight, 1.8–2.0 mm long; lid obliquely rostrate, 1 /3 (−1/2) length of body of capsule; annulus of large separating fugacious cells; basal membrane of peristome of 3–5 rows of cells, projecting above mouth of capsule; spores hardly papillose, 18–22 μm. Capsules common, autumn to spring. n = 24, 28∗ . On highly calcareous chalk or magnesian limestone soil in chalk pits, cuttings, on hillsides. Lowland. Very rare in chalk areas of S. England and chalk and magnesian limestone in N. E. England, Cheshire, Midlothian. 17. GB17 + 4∗ . Circumpolar Boreo-arctic Montane. Rare in Europe from Spain and Greece north to Svalbard, Turkey, Siberia, Tenerife, Algeria, Tunisia, N. America, Greenland. A. brevirostris differs from A. rigida in the hyaline basal part of the leaf as long as or longer than the blade, the synoicous inflorescence and larger spores.

2 A. rigida (Hedw.) Limpr., Laubm. Deutschl., 1888 Tortula rigida (Hedw.) Schrad. ex Turner

(Fig. 105)

Dioicous. Small dull green or brownish patches or scattered plants, c. 2 mm high. Leaves incurved when dry, spreading when moist, mostly 4–6 times as long as wide, lingulate to lingulate-spathulate or lingulate-lanceolate, hyaline basal part shorter than blade, apex rounded and apiculate, rarely obtuse and mucronate, cucullate; costa well defined, ending in apex or excurrent in mucro, in section with 1–3 rows of guide cells and 3–6(−8) rows of stereids; marginal cells of basal part elongate, thin-walled, hyaline. Capsules erect, narrowly ellipsoid, straight, c. 2–3 mm long; lid obliquely rostrate, c. 1/2 length of body of capsule; annulus of large separating fugacious cells; basal membrane of peristome of 3–5 rows of cells, projecting above mouth of capsule; spores ± smooth, 14–16 μm. Capsules common, autumn to spring. n = 24, 26, 28. On bare calcareous soil on banks and cliffs, in quarries, especially in chalk and limestone areas. 0–500 m. Rare and much decreased, from S. Wiltshire east to W. Kent and north to E. Ross, Dublin, Kildare, old records from Down, Antrim. 43, H4. GB33 + 50∗ , IR1 + 5∗ . European Boreal-montane. Greece, N. Italy and Pyrenees north to S. Scandinavia, Faeroes, Caucasus, Turkey, Cyprus, Turkestan, former USSR, N., E. and southern Africa, N. America, Ecuador, Bolivia, Peru, Australia (introduced?). ¨ Hal.) Broth., as A. rigida var. mucronulata (Bruch & Schimp.) Lindb., A. obliquifolia (Mull. was reported from the British Isles by M. C. Delgadillo (Bryologist 78, 245–306, 1975) from Gloucestershire, 1837, coll. Atark and Glasnevin, near Dublin, coll. D. Moore. These specimens are in BM together with a third, also named by Delgadillo, from Newhaven, 1855, coll. Hemmings. A. obliquifolia differs from A. rigida in the leaves having an excurrent costa and the basal membrane of the endostome not projecting above the mouth of the capsule. The specimen from Glasnevin was redetermined A. rigida by M. T. Galego, and all three specimens have tall basal membranes so it would appear that A. obliquifolia does not occur in the British Isles.

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3 A. aloides (D. J. Koch ex Schultz) Kindb., Bih. Kongl. Svenska Vetenskt.-Akad. Handl., 1883 (Fig. 105) Tortula aloides (D. J. Koch ex Schultz) De Not. Dioicous. Dark green to reddish brown patches or scattered plants, 2–5 mm high. Leaves rigid, incurved and glossy when dry, erect-patent when moist, narrowly lingulate or lanceolate, apex obtuse and apiculate to acute or acuminate, apiculus or acumen not reflexed, sometimes hyaline; margins inflexed above; costa ending in apex or shortly excurrent; marginal cells near leaf base quadrate to rectangular, not hyaline. Capsules erect or more usually inclined, narrowly ellipsoid to cylindrical, straight to strongly carved, 1.6–2.4(−2.8) mm long; lid obliquely rostrate; basal membrane of peristome of 1–2 rows of cells, not projecting above mouth of capsule; spores smooth, 18–22(−25) μm. Capsules common, autumn to spring. n = 26∗ . On exposed basic soil on banks, rock ledges, cliffs, sand-dunes, in quarries. 0–450 m. Frequent in the southern half of England and in Wales, rare further north, extending to E. Ross, occasional in Ireland. 86, H26, C. GB312 + 83∗ , IR49 + 8∗ , C3. SubmediterraneanSubatlantic. Europe north to Sweden, Turkey, Cyprus, Caucasus, N. Africa, Newfoundland. The rosettes of dark green succulent-looking, glossy leaves make this and the next species easily recognisable. I have followed Corley et al. (1981) in treating A. ambigua as a separate species as it is usually distinct from A. aloides in the British Isles, but the two do intergrade elsewhere and are treated by some authorities as varieties of a single species. A. aloides has less spreading and frequently more acute leaves than A. ambigua and the capsules are often markedly inclined, but the only constantly reliable characters for separating the two are length of basal membrane and spore size.

4 A. ambigua (Bruch & Schimp.) Limpr., Laubm. Deutschl., 1888 (Fig. 105) A. aloides var. ambigua (Bruch & Schimp.) F. J. Craig., Tortula ambigua (Bruch & Schimp.) Ångstr. Dioicous. Dark green to reddish brown patches or scattered plants, 2–5 mm high. Leaves rigid, curved and glossy when dry, erect-patent to spreading when moist, lingulate-lanceolate, apex cucullate, obtuse, sometimes with reflexed apiculus; margins inflexed; costa ending in apex or shortly excurrent; marginal cells near leaf base quadrate to rectangular, not hyaline. Capsules erect or slightly inclined, cylindrical, straight or slightly curved, (2.0−)2.2–3.2 mm long; lid obliquely rostrate; basal membrane of peristome of 3–5 rows of cells, projecting above capsule mouth; spores ± smooth, (12−)14–16 μm. Capsules common, winter, spring. n = 23 + m, 24, 25 + 2m. On exposed basic soil on banks, rock ledges, cliffs, in quarries. Lowland. Rare to occasional in England and Wales and extending north to N. Northumberland and Westmorland, very rare in Ireland and seen recently

63 Leptobarbula

343

only from E. Cork, Waterford and Clare. 50, H7, C. GB50 + 56∗ , IR3 + 5∗ , C1. European Southern-temperate. Europe north to Sweden, Caucasus, Turkey, Cyprus, Lebanon, Iran, Siberia, Azores, Canary Islands, Tunisia, N. America, Mexico, Australia (introduced?). Tribe 2 Pottieae Lamina cells often convex on both faces. Setae commonly twisted anticlockwise when dry.

63 LEPTOBARBULA SCHIMP., REV. BRYOL., 1876 A monotypic genus with the characters of the species. Derivation: meaning slender Barbula.

1 L. berica (De Not.) Schimp., Rev. Bryol., 1876 (Fig. 106) Dioicous. Plants bright green, scattered or forming dense tufts, to 2 mm high. Stems with central strand, sclerodermis absent or weakly developed, hyalodermis absent. Axillary hairs 6–7 cells long, basal 2 brown. Leaves erect-patent from erect basal part when moist, hardly altered when dry, increasing in size up stems and more crowded near top, very narrowly lanceolate, obtuse; margins plane, papillose-crenulate; costa ending below apex, 2–4 cells wide on adaxial side, cells quadrate, in section with 2 stereid bands but abaxial band weak or absent; cells in lower part of leaf rectangular, incrassate, 4–8 × 12–25 μm, cells above quadrate, very incrassate, densely papillose, opaque, 3–6 μm wide. Perigonial and perichaetial bracts longer than stem leaves with inflated sheathing bases narrowed into patent or spreading ± linear limb, obtuse in outer, acute in innermost perichaetial leaves. Setae long; capsules erect, cylindrical; lid rostrate; peristome with 32 filamentous spirally coiled teeth; calyptrae cucullate; spores c. 8 μm. Capsules very rare. On limestone rocks and stones in woodland, shaded brickwork, stonework and mortar. Lowland. Rare in southern and eastern England from Cornwall east to E. Kent and north to Yorkshire, W. Galway. 27, H1. GB46, IR1. Mediterranean-Atlantic. Mediterranean region and north to Belgium, Germany and the Netherlands, Turkey, Madeira, Azores, N. Africa. Differs from Gymnostomum calcareum in the smaller size of the plants, the leaves being very narrowly lanceolate and gradually tapering instead of lingulate. Unlike L. berica, Gymnostomum calcareum does not have strongly differentiated perigonial and perichaetial leaves. Gyroweisia tenuis has wider leaves, usually abundant gymnostomous capsules and protonemal gemmae. It is uncertain if this species is spreading or whether because of its small size it has been overlooked in the past. For an account of its discovery and a detailed description see J. Appleyard, M. O. Hill & H. L. K. Whitehouse, J. Bryol. 13, 461–70, 1985.

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Fig. 106 Leptobarbula berica: 1, 2, sterile and female shoots (×35); 3, leaves (×60); 4, basal cells (×420); 5, mid-leaf cells (×420); 6, perichaetial leaf (×60).

64 TORTULA HEDW., SP. MUSC. FROND., 1801 Monoicous or dioicous. Plants forming cushions or tufts; stems with central strand. Leaves erect-patent to spreading when moist, usually obovate or spathulate, apex acute to rounded; margins usually recurved below and entire above; costa shortly to longly excurrent, 3–4(−5) cells wide on adaxial side, cells ± quadrate, smooth or papillose, in section adaxial stereid band circular to semicircular; basal cells rectangular, hyaline, thin-walled and often lax, cells above rounded-quadrate to hexagonal, usually thin-walled, papillose, marginal 1–4 rows often smaller, less papillose. Vegetative propagules lacking. Perichaetial leaves similar to or larger than stem leaves. Setae very short to long; capsules usually erect, spherical to cylindrical, dehiscent; peristome teeth 16, perfect, variously divided and often spirally coiled, or irregular, rudimentary or absent;

64 Tortula

345

calyptrae cucullate. Laminal KOH reaction usually yellow. About 165 species world-wide. Derivation: a diminutive meaning twisted, referring to the peristomes. Tortula differs from Syntrichia in the costa in section having a circular or semicircular rather than lunate stereid band and the adaxial costa cells are quadrate rather than elongate. The laminal KOH reaction is yellow in Tortula, red in Syntrichia. Hennediella differs in the leaf margins dentate above and in the red KOH reaction. The descriptions of species 12–16 are based upon those in the first edition of this book by Dr D. F. Chamberlain, when they were included in the genus Pottia.

1 Capsules ± spherical, ovoid, ellipsoid or turbinate, lid mamillate, conical or rostrate, peristome teeth if present straight 2 Capsules cylindrical or rarely narrowly ellipsoid, ± erect, lid very longly rostrate, peristome long, spirally twisted, or capsules absent 8 2 Capsules cernuous or horizontal, leaf margins with border of narrow cells 10. T. cernua Capsules ± erect, leaf margins unbordered 3 3 Peristome teeth well developed 4 Peristome teeth rudimentary or absent 5 4 Leaf margins strongly recurved ± from base to apex, costa thickened in upper part of leaves 11. T. atrovirens Margins recurved below, costa not thickened in upper part 12. T. lanceola 5 Leaf margins plane, cells smooth, capsules turbinate, widest at mouth 16. T. truncata Leaf margins recurved, cells usually papillose, capsules obloid to ellipsoid, widest below mouth 6 6 Cells in upper part of leaf 13–17 μm wide, papillose, spores 19–26 μm 13. T. wilsonii Cells 17–24 μm wide, faintly papillose, spores 25–34 μm 7 7 Leaves spathulate-oblong, apex rounded, costa excurrent 100–1100 μm 14. T. viridifolia Leaves oblong-lanceolate, apex acute, costa excurrent 100–300(−500) μm 15. T. modica 8 Costa excurrent in hyaline hair-point, rarely excurrent in yellowish point, cells 8–16 μm wide at widest part of leaf 9 Costa ending in or below apex or excurrent in yellowish or greenish point, rarely excurrent in hyaline point, leaf cells 16–24 μm wide 10 9 Leaf margins revolute ± from base to apex, peristome teeth free almost to base, plants forming rounded cushions, tufts or patches 8. T. muralis Margins plane or only recurved at middle of leaf, peristome teeth united for 1/ –1/ their length, plants scattered or forming patches 7. T. canescens 3 2 10 Leaves with distinct border of elongate incrassate cells at least below 11

346

11

12 13 14 15

16 Pottiaceae Leaves without border of elongate incrassate cells although marginal band of otherwise differentiated cells sometimes present 12 Leaves mostly 3.5–7.0 mm long, costa ending in apex or excurrent in mucro, 1. T. subulata lower 3/4 of peristome tubular Leaves less than 2 mm long, costa excurrent in yellowish point to 3/4 length of lamina, peristome teeth free almost to base 5. T. marginata Leaf margins revolute ± from base to apex 9. T. leucostoma Leaf margins plane or partly recurved 13 Cells 16–24 μm wide at widest part of leaf 14 Cells 10–16 (−18) μm wide 15 Leaves acute, cells smooth 2. T. cuneifolia Leaf apices rounded, cells papillose 6. T. vahliana Costa ending below apex, margins plane 3. T. freibergii Costa ending in apex or excurrent at least in some leaves, margins plane or recurved 4. T. solmsii

Section 1 Tortula Leaf apices usually rounded; costa usually excurrent in long hyaline point, 3–6 cells wide on adaxial side, cells densely papillose, in section with guide cells; lamina cells relatively small, mostly 10–13 μm wide, densely papillose. Capsules usually with peristomes. 1 T. subulata Hedw., Sp. Musc. Frond., 1801 Autoicous. Dull green patches or scattered plants, rarely more than 10 mm high. Leaves incurved, twisted when dry, spreading when moist, very variable in shape, narrowly lanceolate, narrowly lingulate, spathulate or ovate, obtuse to acute or acuminate; margins recurved below, bordered at least below, entire or opaquely toothed above; costa stout, percurrent or excurrent in mucro; cells in lower part of leaf rectangular, hyaline, at margins narrower with marginal band of narrow incrassate cells extending up margins half way or more up leaf and sometimes forming conspicuous yellow border, cells in upper part of leaf irregularly hexagonal or ± quadrate, papillose, opaque, variable in size, 12–28 μm wide at widest part of leaf. Setae reddish; capsules cylindrical, slightly curved; peristome tubular for c. 3/4 of its length, spirally coiled; spores 10–28 μm. Capsules common, spring, summer. 1 Leaves acute or acuminate, border poorly developed and rarely reaching half way up leaf, cells weakly papillose, 16–28 μm wide at widest part of leaf var. graeffii Apices rounded to acuminate, border extending half way or more up leaf, cells strongly papillose, (10−)12–20(−22) μm wide 2 2 Leaves narrowly lanceolate, acuminate, border strongly developed, extending almost to acuminate apex var. angustata Leaves narrowly lingulate to spathulate or ovate-lanceolate, apices rounded to 3 acuminate, border extending 1/2–3/4 way up leaf

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347

3 Leaves usually narrowly lingulate to ovate-lanceolate, obtuse to acuminate, var. subulata border extending 1/2–3/4 way up leaf Leaves spathulate, apices rounded or obtuse and apiculate, border poorly var. subinermis developed, usually ending c. 1/2 way up leaf Var. subulata (Fig. 107) Leaves narrowly lingulate to ovate-lanceolate, obtuse to acuminate; margins bordered to 1/2–3/4 way up leaf, entire or opaquely toothed above; cells 12–20(−22) μm wide at widest part of leaf. Spores 10–20 μm. n = 12, 13, 14∗ , 18, 24, 26∗ , 48, 48 + m, 60. On light neutral to basic soil in open to sheltered sites on roadsides, banks, rock ledges, in woods and on tree roots and boles. 0–500 m. Frequent or common throughout most of Britain, rare to occasional in Ireland. 110, H25. GB627 + 141∗ , IR25 + 13∗ . Eurosiberian Southern-temperate. Europe north to Fennoscandia, Faeroes, Caucasus, Turkey, Kashmir, China, Canary Islands, Madeira, Algeria, eastern N. America. Var. angustata (Schimp.) Limpr., Laubm. Deutschl., 1888 T. angustata Limpr.

(Fig. 107)

Leaves narrowly lanceolate, tapering to acuminate apex; margins strongly bordered almost to apex, irregularly and opaquely toothed above; cells strongly papillose, mostly 12–20 μm wide at widest part of leaf. Spores 10–12 μm. On light, usually acidic soil in shady places. Lowland. Rare, from Devon and S. Hampshire north to the Lothians, N. Aberdeen, Orkney, Shetland, recorded from 28 vicecounties but seen recently from only 10, Down (old record). 28, H1. Europe north to Scandinavia, Turkey, Kashmir, China, Canary Islands, Algeria, Morocco, Tunisia, N. America. Var. subinermis (Bruch & Schimp.) Wilson, Bryol. Brit., 1855 (Fig. 107) Leaves spathulate, apex obtuse or rounded and apiculate, border poorly developed, ending at about half way up leaf; cells strongly papillose, 12–16 μm wide at widest part of leaf. Spores c. 16 μm. n = 24. On soil, tree boles and roots by streams and rivers. Lowland. Rare, scattered localities from N. Somerset and W. Sussex north to Stirling and N. Aberdeen, Down. 34, H1. Europe north to Scandinavia, Turkey, Kashmir, China, Canary Islands, Algeria, N. America. Var. graeffii Warnst., Krypt.-Fl. Brandenburg, Laubm., 1904 (Fig. 107) Leaves acute to acuminate, border poorly developed, ending about half way up leaf; cells opaquely papillose, 16–24 μm wide. Spores 14–20 μm. n = 26∗ . On light calcareous soil. Lowland. Rare to occasional, from N. Somerset, Dorset and I. of Wight north to Shetland, Westmeath, Cavan. 19, H2. Austria, Denmark, France, Germany, Norway, Poland, Sweden, Switzerland, Turkey. The usually present, relatively large, slightly curved capsules arising from rosettes of leaves make this plant readily recognisable. T. subulata is extremely variable in leaf characters, spore size and chromosome number. The status of var. angustata and var. subinermis is open

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Fig. 107 1–3, Tortula subulata var. subulata: 1, leaves; 2, marginal cells at widest part of leaf; 3, capsule (×7). 4–5, T. subulata var. subinermis: 4, leaf, 5, marginal cells at widest part of leaf. 6–7, T. subulata var. graeffii: 6, leaf; 7, marginal cells at widest part of leaf. 8–9, T. subulata var. angustata: 8, leaf; 9, marginal cells at widest part of leaf. 10–12, T. cuneifolia: 10, leaves; 11, cells at widest part of leaf; 12, capsule (×10). Leaves ×10, cells ×280.

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to question as they may be difficult to separate from the type and further investigation is required. Var. graeffii retains its characters in cultivation and appears to have a genetic basis (see A. C. Crundwell, Trans. Br. Bryol. Soc. 2, 292, 1956).

2 T. cuneifolia (Dicks.) Turner, Muscol. Hibern. Spic., 1804 (Fig. 107) Green patches or scattered plants, c. 5 mm high. Leaves shrunken, appressed when dry, lower erect-patent, upper thin, soft, crowded, patent to erect-patent when moist, broadly spathulate, rarely more than twice as long as wide, concave, abruptly narrowed to acute apex; margins plane, entire; costa percurrent to excurrent in smooth yellowish or sometimes hyaline point to 1/3 length of lamina; cells in lower part of leaf rectangular, above irregularly quadrate-hexagonal to shortly rhomboidal, thin-walled, smooth, pellucid, 16–24 μm wide at widest part of leaf, marginal cells thicker-walled but of similar shape to inner cells. Setae red; capsules cylindrical to narrowly ellipsoid; peristome teeth free nearly to base, spirally coiled; spores 14–18 μm. Capsules common, spring. n = 20∗ . On soil and in rock crevices on banks, in old quarries and fallow fields, especially near the coast. Lowland. Rare in southern Britain and much decreased, extending north to Anglesey and E. Suffolk, recorded from 21 vice-counties but seen recently only in 9, rare in Ireland and not seen recently. 21, H8, C. GB9 + 30∗ , IR10∗ , C2. MediterraneanAtlantic. S. and W. Europe, Turkey, Cyprus, Syria, Palestine, C. Asia, Macaronesia, Algeria, Morocco, Tunisia. T. cuniefolia has decreased markedly and is no longer known from inland habitats and has vanished from many coastal sites. This and the next two species are extremely variable in leaf shape and may be confused. T. freibergii differs in the usually narrower, bordered leaves with the costa usually ending below the apex and smaller cells. In T. solmsii at least some of the marginal cells of the leaves are usually of different shape from the inner cells which are smaller and densely papillose. This species is treated as vulnerable in the Red List of British Mosses.

3 T. freibergii Dixon & Loeske, Ann. Bryol., 1934 (Fig. 108) Autoicous or apparently dioicous. Yellowish green to dark green patches, to 2 mm high. Leaves slightly twisted, incurved when dry, erect-patent to spreading when moist, slightly concave, lingulate-lanceolate to spathulate, 1.75–4.00 times as long as wide, apex rounded to obtuse, rarely subacute, frequently with short apiculus; margins plane, entire or crenulate; costa ending below apex, rarely percurrent, adaxial cells rectangular; cells in lower part of leaf narrowly rectangular, above quadrate to rectangular, thin-walled, papillose, pellucid, 10–14(−18) μm wide at widest part of leaf, smaller towards apex, smooth or rarely sparsely papillose, pellucid, up to 12 marginal rows with thicker walls, some rectangular to elongate, forming sometimes distinct border. Setae pale yellow; capsules narrowly ellipsoid to cylindrical, ± symmetrical; peristome teeth free almost to base, spirally coiled; spores 8–12 μm. Capsules common, spring. n = 26∗ . On moderately exposed base-poor sandstone rocks and walls. Lowland. Very rare, E. Sussex,

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Fig. 108 1–3, Tortula vahliana: 1, leaves (×25); 2, marginal cells from widest part of leaf; 3, capsule. 4–5, T. solmsii: 4, leaves (×50); 5, marginal cells at widest part of leaf. 6–8, T. freibergii: 6, leaves (×20); 7, marginal cells at widest part of leaf; 8, capsule. Cells ×280, capsules ×15.

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Cheshire, S. Lancashire, N. E. Yorkshire. 4. GB6. Suboceanic Southern-temperate France, Portugal, Spain and Giglio Is. (Italy). For differences from T. cuneifolia and T. solmsii see under those species. For the occurrence of this plant in England see A. C. Crundwell & E. Nyholm, J. Bryol. 7, 161–4, 1972, and for an augmented account see T. L. Blockeel & F. J. Rumsey, J. Bryol. 16, 179–85, 1990. This plant is listed as vulnerable in the Red Data Book of European Bryophytes.

4 T. solmsii (Schimp.) Limpr., Laubm. Deutschl., 1888 (Fig. 108) Dioicous. Dense low tufts or scattered plants, 1.0–2.5 mm high. Leaves erect, slightly twisted when dry, erect-patent when moist, lingulate, spathulate or ovate, apex rounded to obtuse or acute or obtuse and mucronate; margins plane or narrowly recurved at middle of leaf, papillose-crenulate; costa ending below apex to excurrent to 400 μm in yellowish to greenish hair-point; basal cells thin-walled, hyaline, lax, narrowly rectangular, shorter and narrower towards margins, upper cells variable in shape, quadrate to rectangular or hexagonal, densely papillose, opaque, 12–16 (−18) μm wide in mid-leaf, 2–5 (−8) marginal rows rectangular and/or quadrate, ± smooth, less well or hardly differentiated in shade forms, usually unistratose. Setae yellowish when young, brown with age; capsules erect, shortly cylindrical; lid straight or slightly oblique; peristome teeth c. 600 μm long, spirally coiled; spores 10–15 μm. Capsules occasional, spring. On neutral to slightly basic rock or in crevices in granite walls. Lowland. Very rare, Scilly Isles, W. Cornwall, S. Devon. 2. GB4. Mediterranean-Atlantic. Mediterranean and Atlantic Europe, extending north to England, Turkey, Macaronesia, Algeria, Morocco. A variable species, shade forms differing markedly from plants in exposed habitats. Shade forms have lingulate-obovate, obtuse to acute leaves with costa ending well below the apex to percurrent, the cells less densely papillose and marginal rows poorly or hardly differentiated from inner cells. In open-ground forms the leaves are lingulate or spathulate with rounded to obtuse apices, costas ending below apex to excurrent in hair-point, cells strongly papillose with marginal cells differentiated and forming a distinct border. Confused in Britain with T. vahliana, which differs in the more spreading leaves, the margins papillose-crenulate, the narrowly cylindrical capsules and in being synoicous. T. freibergii has more spreading leaves with the costa ending well below the apex, the broader border 4–6(−12) cells wide and the other cells less strongly papillose, the capsules cylindrical and in being autoicous. The above description is based, largely upon that in a paper by D. G. Long & M. O. Hill (J. Bryol. 12, 159–69, 1982), where a detailed account of the species may be found.

5 T. marginata (Bruch & Schimp.) Spruce, London J. Bot., 1845 (Fig. 109) Dioicous. Yellowish green patches, 2–3 mm high. Leaves twisted when dry, erectpatent when moist, narrowly lanceolate or lingulate to lingulate-spathulate, occasionally spathulate, apex obtuse or acute; margins plane, bordered, sinuose with projecting cell walls; costa yellowish, excurrent in yellowish point to half length of lamina; cells in lower part of leaf narrowly rectangular, cells above shortly rectangular to irregularly quadrate-hexagonal, not incrassate, papillose, opaque,

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Fig. 109 1–4, Tortula muralis var. muralis: 1, leaf; 2, cells from widest part of leaf; 3, capsule; 4, peristome. 5, T. muralis var. aestiva: leaf. 6–9, T. canescens: 6, leaf; 7, cells from widest part of leaf; 8, capsule; 9, peristome. 10–12, T. marginata: 10, leaves; 11, marginal cells; 12, capsule. Leaves ×25, cells ×420, capsules ×15, peristomes ×62.5.

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8–14 μm wide at widest part of leaf, 2–4 marginal rows elongate, incrassate, forming distinct border extending almost from base to apex. Setae orange-red; capsules shortly cylindrical, symmetrical; peristome teeth free almost to base; spores c. 8 μm. Capsules common, spring. n = 24. On damp usually shaded basic rocks and walls in both natural and man-made habitats. Locally common in lowland England north to Cheshire and Durham, very rare elsewhere, Berwick, Argyll, Dunbarton, a few localities in Ireland, Guernsey. 56, H10, C. GB245 + 35∗ , IR7 + 4∗ , C1∗ . Mediterranean-Atlantic. S. and W. Europe extending north to Germany, Turkey, Cyprus, W. Asia, India, Macaronesia, N. Africa. Differing from T. muralis in the plants forming patches in damp shaded habitats and in the bordered leaves with the costa excurrent in a yellowish point.

6 T. vahliana (Schultz) Mont. in Gay, Hist. Phys. Cuba Bot. Pl. Cell, 1850 (Fig. 108) Autoicous. Bright green patches or scattered plants, to 5 mm high. Leaves erect, twisted when dry, thin, soft, spreading when moist, narrowly lingulate to spathulate, apices rounded; margins plane or recurved at middle of leaf, papillosecrenulate; costa excurrent in smooth greenish point to c. 220 μm long; cells in lower part of leaf rectangular, above hexagonal, thin-walled, papillose, pellucid, 16–20 μm wide, 1–2 marginal rows ± quadrate, less papillose. Setae red; capsules cylindrical, slightly curved; peristome teeth free almost to base, spirally coiled; spores 12–16 μm. Capsules occasional, spring. On shaded moist chalky clay soil on roadsides and in old chalk pits. Lowland. Very rare, Devon, S. Somerset, E. Kent, N. Essex, E. Suffolk, Cambridge, old records from W. Kent, Gloucester, Hereford and Dublin. 11, H1. GB9 + 9∗ , IR3∗ . Mediterranean-Atlantic. Mediterranean and Atlantic Europe, extending north to the British Isles, Turkey, Cyprus, Canary Islands, N. Africa, Chile. Over-recorded in the past because of confusion with forms of T. muralis occurring on soil. In T. muralis the leaf margins are recurved almost from base to apex, the leaf cells are smaller and the hair-points are usually hyaline.

7 T. canescens Mont., Arch. Bot. (Paris), 1833 (Fig. 109) Autoicous. Dense patches or scattered plants, 1–5 mm high. Leaves erect, flexuose, scarcely twisted when dry, erect-patent to patent when moist, from broad base broadly ovate to lanceolate or spathulate, not or scarcely constricted at or below middle, obtuse; margins plane or recurved at middle of leaf; costa strong, excurrent in smooth hyaline hair-point to 1/2–2 /3 length of lamina; cells in lower part of leaf rectangular, hyaline, cells above hexagonal, papillose, not incrassate, opaque, 12–16 μm wide at widest part of leaf. Setae reddish; capsules cylindrical; peristome tubular for 1/3–1/2 its length, spirally coiled; spores 14–16 μm. Capsules common, late winter, spring. n = 26∗ . On acidic soil in turf and on and among rocks, on shady banks and in wall crevices, in open situations. Lowland. Rare, Cornwall, N. Devon, Montgomery, Merioneth, Kintyre, old records from S. Devon, E. Sussex,

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Radnor, Pembroke, Jersey. 10, C. GB17 + 5∗ , C1∗ . Mediterranean-Atlantic. Europe north to Germany, Caucasus, Turkey, C. Asia, Madeira, Canary Islands, N. Africa. Resembling T. muralis, which rarely grows on soil, differing in the leaf margins plane or only recurved at the middle of the leaf, the peristome tubular for 1/3–1/2 its length and larger spores.

8 T. muralis Hedw., Sp. Musc. Frond., 1801 Autoicous. Small cushions, tufts or patches, green when moist, usually hoary and blackish when dry, rarely exceeding 10 mm high. Leaves twisted or curved when dry, erect-patent to squarrose-spreading when moist, lingulate or lingulatespathulate, apex obtuse or rounded, sometimes emarginate; margins strongly recurved almost from base to apex; costa stout, often reddish, usually excurrent in smooth hyaline hair-point to as long as lamina, rarely excurrent in short yellowish green point; cells in basal part of leaf rectangular, smaller towards margins, above quadrate-hexagonal, incrassate, papillose, opaque, 8–16(−20) μm wide at widest part of leaf, 1–2 marginal rows less papillose, more incrassate. Setae purple; capsules erect, cylindrical or narrowly ellipsoid, straight; peristome teeth free almost to base, bifid into filiform spirally coiled papillose segments; spores 7–12(−14) μm. Capsules common, spring, summer. Plants forming hoary cushions, tufts or patches, leaves with costa excurrent in hyaline hair-point var. muralis Plants forming non-hoary patches, costa excurrent in yellowish green point var. aestiva Var. muralis (Fig. 109) Plants forming cushions, tufts or patches, hoary when dry. Leaves lingulate or lingulate-lanceolate; costa excurrent in ± smooth hyaline hair-point. n = 13 + m, 18, 24, 26∗ , 26 + m∗ , 27∗ , c. 40, 48∗ , 50∗ , 52∗ , 55∗ , 60, 66. On usually exposed mortared or basic walls, roof tiles, concrete and basic rocks, rarely on acidic substrates, bark or hard-packed soil. 0–950 m. Very common in urban areas and able to withstand atmospheric pollution, occasional in natural habitats. 112, H40, C. GB1925 + 93∗ , IR334 + 20∗ , C3. Circumpolar Southern-temperate. Cosmopolitan. Var. aestiva Hedw., Sp. Musc. Frond., 1801 (Fig. 109) Plants in patches, bright green when moist, not hoary when dry. Leaves narrowly lingulate-spathulate; costa excurrent in short yellowish green point. n = 13, 26, 48. Occasional from S. Devon east to W. Kent and north to Wigtown and Berwick. 34. Europe north to Sweden, Caucasus, Turkey, E. Asia, Azores, Madeira, N. Africa, N. and southern S. America. Var. aestiva is possibly only a habitat modification and its status requires investigation. Large forms of T. muralis with large sporophytes are diploid and are conspicuously different from normal-sized plants and have been referred to as var. rupestris Chev. However, these intergrade completely with smaller plants, some of which are also diploid, and there is

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no correlation between chromosome number and morphology and the variety cannot be maintained (see M. E. Newton, Trans. Br. Bryol. Soc. 5, 523–35, 1968).

9 T. leucostoma (R. W. Br.) Hook. & Grev., Edinburgh J. Sci., 1824 (Fig. 110) Desmatodon leucostaoma (R. W. Br.) Berggr., D. suberectus (Hook.) Limpr., Tortula suberecta Hook. Autoicous. Tufted or gregarious ephemeral plants, 2–3 mm high. Leaves erect when dry, erect-patent when moist, broadly to narrowly triangular, ovatelanceolate or lanceolate, acute; margins revolute almost to apex, papillosecrenulate above; costa stout, excurrent in long or short yellowish hair-point; basal cells rectangular, hyaline, becoming smaller, quadrate, papillose, opaque above, 8–12 μm wide in mid-leaf, smaller and very obscure towards apex, cells towards margins less papillose, pellucid, forming pale band. Capsules erect or inclined, cylindrical, straight or slightly curved; lid rostrate; peristome with tall basal membrane, teeth spirally coiled; spores coarsely papillose, 20–26 μm. Capsules common, summer. On soil amongst calcareous rocks and on ledges. 550 m. Very rare, E. Perth, S. Aberdeen. 2. GB2. Circumpolar Arctic-montane. Montane and northern Europe north to Svalbard, N. and E. Asia, N. America, Greenland. A very rare species often associated with the similarly rare plant Stegonia latifolia; it is treated as vulnerable in the Red List of British Mosses.

10 T. cernua (Huebener) Lindb., Musci Scand., 1887 Desmatodon cernuus (Huebener) Bruch & Schimp.

(Fig. 110)

Autoicous. Bright green patches, 2–7 mm high. Leaves erect, twisted when dry, erect-patent to patent when moist, lanceolate, oblanceolate or spathulate, acuminate; margins bordered, recurved to middle of leaf or higher, denticulate above; costa stout, excurrent in cuspidate point; cells in basal part of leaf rectangular, hyaline, narrower at margins, cells above variable in shape and size, ± irregularly hexagonal, smooth or papillose, pellucid 10–20 μm wide at widest part of leaf, 1–3 marginal rows longer and narrower, forming distinct border, bistratose below. Setae red, flexuose; capsules cernuous or horizontal, ovoid, curved; lid obliquely rostrate; peristome teeth ± straight; spores coarsely papillose, 36–40 μm. Capsules common, autumn. n = 25, 26∗ . On highly calcareous soil on lime waste and quarry spoil, by paths and in quarries. Lowland. Very rare and sporadic in occurrence. Derby, Cheshire, S. W. Yorkshire, old records from Nottingham and Mid-West Yorkshire. 5. GB5 + 5∗ . Circumpolar Boreal-montane. Europe, extending north to Svalbard, Siberia, Mongolia, C. Asia, Tibet, N. America, Greenland. This species is considered endangered in the Red List of British Mosses and is a protected plant under the Wildlife and Countryside Act.

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Fig. 110 1–4, Tortula atrovirens: 1, leaves (×25); 2, marginal cells; 3, mid-leaf cells; 4, capsule. 5–8, T. leucostoma: 5, leaf (×35); 6, marginal cells; 7, mid-leaf cells; 8, old capsule. 9–12, T. cernua: 9, leaves (×25); 10, marginal cells; 11, mid-leaf cells; 12, capsule. Cells ×420, capsules ×15.

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¨ 11 T. atrovirens (Sm.) Lindb., Ofvers F¨orh. Kongl. Svenska Vetensk-Akad. 1864 (Fig. 110) Desmatodon convolutus (Brid.) Grout Autoicous. Dark green tufts or patches, c. 2 mm high. Leaves spirally twisted when dry, erect-patent or patent when moist, concave, oblanceolate or obovate, broadly acute to obtuse and apiculate; margins usually strongly recurved, entire; costa stout, thickened in upper half of leaf, excurrent in mucro; basal cells ± rectangular, hyaline, cells above regularly quadrate-hexagonal, finely papillose, 10–12 μm wide at widest part of leaf. Capsules erect or slightly inclined, ovoid or ellipsoid; lid conical; peristome with short basal membrane, teeth straight; spores finely papillose, 24–26 μm. Capsules common, winter, spring. n = 26∗ . In open coastal situations on sandy soil or soil in rock crevices and on walls, often close to high tide level, very rare inland. Lowland. Occasional along the coast from Cornwall east to E. Kent and north to I. of Man, N. Northumberland, Dumfries, Banff and E. Ross, Hereford, Warwick, Derby, very rare on Irish coasts. 30, H10, C. GB54 + 33∗ , IR1 + 9∗ , C6. Circumpolar Southern-temperate. More or less cosmopolitan. Section 2 Pottia (Ehrh. ex Rchb.) Kindb., Bih. Kongl. Svenska Vetensk.-Ak. Handl., 1883 Leaves usually acute; costa usually shortly excurrent in yellowish brown point, 2–3 cells wide on adaxial side, these cells often bulging or forming low lamellae, smooth or with 1–2 papillae per cell; lamina cells usually large, 15–24 μm wide, smooth or weakly papillose. Peristome often rudimentary or short. The descriptions of species 12–16 were written by Dr D. F. Chamberlain as part of his account of the genus Pottia for the first edition of this book.

Species 12–16 by D. F. Chamberlain 12 T. lanceola R. H. Zander, Bull. Buffalo Soc. Nat. Sci., 1993 ¨ Hal. Pottia lanceolata (Hedw.) Mull.

(Fig. 112)

Autoicous. Plants in bright green tufts or patches, ephemeral, to 5 mm high. Leaves ovate-lanceolate, 2.5–3.0 times as long as wide, acute; margins recurved nearly to apex, ± entire; costa excurrent 150–300 μm; upper cells quadrate, thinwalled, papillose, 13.0–17.0(−19.5) μm wide. Setae 2.8–5.5 mm long; capsules ellipsoid, 1.00–1.75 × 0.6–0.9 mm, with 2–4(−7) rows of thick-walled cells below constricted mouth; lid longly rostrate; annulus present; peristome teeth well developed, straight, 250–450 μm long, imperfectly divided above; spores densely and finely papillose, (19.0−)21.5–30.0 μm; calyptrae smooth. Capsules common, winter, early spring. n = 23, 24∗ , 26, 26 + m. On open or disturbed usually calcareous soil in thin turf, quarries, on sea-cliffs, wall tops. 0–550 m. Frequent in the south, becoming rarer in the north, extending to Caithness, rare in Ireland.

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75, H6. GB174 + 105∗ , IR31 + 4∗ . Circumpolar Southern-temperate. Europe north to S. Scandinavia, W. Asia, Japan, Madeira, Canary Islands, N. Africa, N. America. Pale brown to brown rhizoidal gemmae, variable in size and shape, isodiametric and from 80 to 300 μm or ellipsoid or pyriform and 50 × 300 to 100 × 400 μm have been reported from Belgian and German material (see T. Arts, Lindbergia 13, 130–2, 1987).

13 T. wilsonii (Hook.) R. H. Zander, Bull. Buffalo. Soc. Nat. Sci., 1993 Pottia asperula Mitt., P. wilsonii (Hedw.) Schimp.

(Fig. 111)

Paroicous. Bright or pale green tufts, c. 5 mm high. Leaves obovate-lanceolate, 2.5–4.0 times as long as wide, apex acute to rounded; margins recurved; costa excurrent 150–650 μm; upper cells quadrate, strongly papillose, pellucid, walls moderately thick, 15–17 μm wide. Setae 2.0–3.3 mm long; capsules obovoid, 0.8–1.7 × 0.7–1.0 mm, widest well below constricted mouth, with 3–5 rows differentiated cells below mouth; lid rostrate; annulus present; peristome absent or rudimentary and up to 75 μm long; spores granulate-papillose, 19.0–26.5 μm; calyptrae smooth to scabrid. Capsules common, spring. On soil on rocky cliffs, Cornish ‘hedges’, wall tops, sandy banks, hedge banks and on wall tops. Lowland. Occasional along the coast from Cornwall to E. Norfolk and S. Lancashire but lost from all inland and many coastal localities (recorded from 21 British vice-counties but seen recently only in five), Jersey, old records from Guernsey, E. Cork, Dublin and Wicklow. 21, H3, C. GB20 + 34∗ , IR6∗ , C1 + 3∗ . Mediterranean and western Europe, extending north to the British Isles, British Columbia. T. wilsonii has decreased markedly since its discovery by W. Wilson in Cheshire in 1828. It is no longer known in any inland localities and has vanished from many coastal sites. At least some plants of the type specimen of P. asperula Mitt. fall within the range of P. wilsonii. This species is considered endangered in the Red List of British mosses.

14 T. viridifolia (Mitt.) Blockeel & A. J. E. Sm., J. Bryol., 1998 (Fig. 111) Pottia crinita Wilson ex Bruch & Schimp., P. viridifolia Mitt., P. wilsonii var. crinita (Wilson ex Bruch & Schimp.) Warnst. Autoicous. Dense light or pale green tufts, to 5 mm high. Leaves spathulate-oblong, (2.5−)3.0–4.0 times as long as wide, apices obtuse or rounded; margins recurved; costa excurrent 100–1100 μm; upper cells quadrate, papillose, thin-walled, 17– 24 μm wide. Setae 2–4 mm long; capsules obloid, 0.8–1.7 × 0.6–1.0 mm, widest at or slightly constricted towards mouth, with 2–4 rows thin-walled differentiated cells below mouth; lid rostrate; annulus present; peristome absent; spores granulate-papillose, 25–35 μm; calyptrae ± roughened, occasionally scabrous. Capsules common, spring. n = 48∗ . On soil on banks, cliffs, stream banks, ant hills and by paths. Lowland. Frequent along the coast from Cornwall east to Sussex and north to Kintyre, very rare along east coast north to Shetland, Radnor, rare along Irish coast. 39, H12, C. GB95 + 24∗ , IR4 + 8∗ , C8. Mediterranean-Atlantic. S. and

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Fig. 111 1–4, Tortula viridifolia: 1, plant (×10); 2, cells at mouth of capsule (×450); 3, upper leaf (×20); 4, cells from upper part of leaf (×430). 5–8, T. wilsonii: 5, cells at mouth of capsule (×450); 6, plant (×10); 7, upper leaf (×20); 8, cells from upper part of leaf (×430).

W. Europe north to Faeroes, Turkey, Israel, S. W. Asia, Gran Canaria, Tenerife, Algeria, Morocco. Plants with shortly excurrent costae have been described as var. viridifolia (Mitt.) Kindb. of Pottia crinita (i.e. T. viridifolia) but as there is no other reliable difference, nor any clear cut discontinuity in the degree of excurrence of the costa, the variety is not recognised here.

15 T. modica R. H. Zander, Bull. Buffalo Soc. Nat. Sci. 1993 (Fig. 112) ¨ Pottia intermedia (Turner) Furnr., P. littoralis Mitt., P. truncata var. major (F. Weber & D. Mohr) Bruch & Schimp. Autoicous. Patches or scattered plants, to 15 mm high. Leaves oblong-lanceolate, 3–4 times as long as wide, acute; margins plane or recurved, entire or crenulate above; costa excurrent to 100–300(−500) μm; upper cells quadrate, smooth or slightly papillose, 17–22 μm. Setae 4.0–6.2 mm; capsules obloid, 0.8–1.6 × 0.6– 1.0 mm, with 3–5 rows thick-walled differentiated cells below slightly constricted

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Fig. 112 1–4, Tortula truncata: 1, plant; 2, cells from mouth of capsule (×450); 3, leaf (×40); 4, cells from upper part of leaf. 5–8, T. modica: 5, cells at mouth of capsule (×450); 6, plant; 7, leaf (×20); 8, cells from upper part of leaf. 9–12, T. lanceola: 9, plant; 10, peristome teeth; 11, leaf (×20); 12, cells from widest part of leaf. Plants ×10, leaf cells ×430.

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mouth; lid rostrate; annulus present; peristome absent or rudimentary, reduced to a basal membrane 35 μm high; spores papillose, 17–34 μm; calyptrae smooth or slightly scabrous. Capsules common, mainly winter and spring. n = 52. On disturbed, calcareous or acidic soil, in arable fields, quarries, gardens, coastal turf and on banks. Lowland. Widespread but local, extending north to Ross, rare in Ireland. 86, H16, C. GB218 + 101∗ , IR7 + 13∗ , C5. Circumpolar Temperate. Europe north to S. Scandinavia, Iceland, Turkey, China, Japan, N. and C. America, Australia. Rhizoidal gemmae, indistinguishable from those of T. lanceola, have been reported from Belgian material (T. Arts, Lindbergia 13, 130–2, 1987). Intermediates between T. lanceola and T. truncata are often found with one or both of these species, and are possibly hybrid derivatives of them. May be distinguished from T. lanceola by capsule shape and the absent or rudimentary peristome and from T. truncata by the presence of an annulus and several rows of thick-walled cells below the capsule mouth. The plant referred to as var. littoralis (Mitt.) Corb. by Dixon & Jameson (1924), which in its extreme state is a well marked form with thick-walled smooth leaf cells and relatively narrow capsules, may be of different origin from the typical form. On present evidence it is not sufficiently distinct from the type to be maintained as a variety.

16 T. truncata (Hedw.) Mitt. in Godman, Nat. Hist. Azores, 1870 (Fig. 112) ¨ Pottia truncata (Hedw.) Bruch & Schimp., P. truncatula (With.) Buse Autoicous. Ephemeral plants forming dull green tufts or patches, to 10 mm high. Leaves oblong-lanceolate, 3–4 times as long as wide, acute; margins plane, slightly denticulate above; costa excurrent 50–300 μm; upper cells quadrate, 17–24 μm wide, thin-walled, smooth. Setae 2.0–3.5 mm long; capsules turbinate, 0.9–1.2 × 0.65–1.00 mm, widest at mouth, with 1–2 rows thin-walled differentiated cells below mouth; lid rostrate; annulus and peristome lacking; spores 24–36 μm; calyptrae smooth. Capsules throughout year but more commonly in spring. n = 20∗ , 25, 26, 52∗ . On disturbed non-calcareous soil in fields, gardens, quarries, on roadsides, woodland rides. Lowland. Common in the south, becoming less frequent in the north. 110, H35, C. GB1164 + 76∗ , IR136 + 7∗ , C8 + 1∗ . Circumpolar Temperate. Europe north to Fennoscandia, Turkey, Asia, Macaronesia, Algeria, Morocco, N. and C. America, New Zealand. Rhizoidal gemmae indistinguishable from those of T. lanceola have been reported from Belgium (T. Arts, Lindbergia 13, 130–2, 1987). Occasional gigas forms, about twice the size of normal plants with larger spores, may be encountered either as solitary plants in normal populations or as a pure population.

65 PROTOBRYUM (LIMPR.) J. GUERRA & M. J. CANO, J. BRYOL., 2000 D. F. Chamberlain

A monotypic genus with the characters of the species.

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Derivation: meaning first Bryum. For the reasons for placing the species in its own genus see J. Guerra & M. J. Cano, J. Bryol. 22, 91–7, 2000.

1 P. bryoides (Dicks.) J. Guerra & M. J. Cano, J. Bryol., 2000 Pottia bryoides (Dicks.) Mitt., Tortula protobryoides R. H. Zander

(Fig. 113)

Autoicous. Ephemeral gregarious dull green or brownish plants, 2–5 mm high. Upper leaves much larger than lower, lanceolate, 2.5–4.0 times as long as wide, acuminate, upper leaves much longer than lower; margins recurved, entire; costa excurrent 250–750 μm long; upper cells quadrate, smooth or slightly papillose, 16– 24 μm wide. Setae 2.0–5.5 mm; capsules ellipsoid, 1.0–1.8 × 0.7–0.9 mm, cleistocarpous but with at least one row of differentiated cells at base of beak; peristome rudimentary; spores minutely papillose, 25–32 μm; calyptrae smooth. Capsules common, winter, spring. On exposed basic soil in grassland, quarries, gravel pits, on banks, roadsides, tracks, paths, and cliffs by the sea. Lowland. Occasional in lowland England, rare in Wales, very rare in Scotland, extending north to Caithness, old records from Dublin, Antrim. 57, H2. GB98 + 53∗ , IR2∗ . European Temperate. Europe, W. Asia, western N. America. Rhizoidal gemmae, indistinguishable from those of T. lanceola, have been reported from Belgium (T. Arts, Lindbergia 13, 130–2, 1987).

66 PHASCUM HEDW., SP. MUSC. FROND., 1801 Two species with the characters of the species below. Derivation: from the Ancient Greek name for a plant of now unknown identity.

1 P. cuspidatum Hedw., Sp. Musc. Frond., 1801 Tortula acaulon (With.) R. H. Zander, T. atherodes R. H. Zander, P. cuspidatum var. curvisetum Nees & Hornsch. Autoicous or paroicous. Ephemeral plants forming pale green tufts, (1−)2– 5(−9) mm high. Leaves slightly twisted, appressed-flexuose when dry, lower patent, upper imbricate to convolute when moist, lower leaves ovate, upper and perichaetial leaves larger, ovate to ovate-lanceolate, acute; margins recurved, entire; costa excurrent; cells very variable, lower lax, above irregularly rectangular to hexagonal, usually thin-walled, smooth to strongly papillose, 9–21 × 11–31 μm in upper part of leaf. Setae short, 0.1–0.5 mm long, straight or curved; capsules immersed or slightly emergent, erect or inclined. Cleistocarpous, subglobose, shortly apiculate; spores 25–40(−44) μm. Capsules common throughout year. 1 Plants 4.5–9.0 mm high, stems branching from above var. schreberianum Plants rarely more than 4 mm high, stems branching from base

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Fig. 113 1–5, Phascum cuspidatum var. cuspidatum: 1, plant; 2, leaves; 3, adaxial cells of costa from upper part of leaf (×420); 4, costa section from upper part of leaf (×420); 5, capsules (×10). 6, P. cuspidatum var. piliferum: leaf. 7–8, P. cuspidatum var. papillosum: 7, adaxial side of costa from upper part of leaf (×420); 8, section of costa from upper part of leaf (×420). 9, P. cuspidatum var. schreberianum: plant. 10–13, Protobryum bryoides: 10, plant: 11, leaf; 12, leaf apex; 13, cells (×340). Plants ×10, leaves ×20.

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2 Costa excurrent in slightly flexuose hyaline point 0.6–1.4 mm long 2 var. piliferum Costa excurrent in yellowish cuspidate point to 0.6 mm long 3 3 Adaxial cells of upper part of costa rectangular, cells in upper part of lamina 10–21 × 21–31 μm, smooth or weakly papillose, spores with truncate or rounded papillae var. cuspidatum Adaxial cells of costa quadrate or shortly rectangular, cells in upper part of lamina 9–15 × 11–20 μm, papillose, spores spinosely papillose var. papillosum Var. cuspidatum (Fig. 113) Plants (1.0−)2.0–4.5 mm high. Stems branched or forked at base. Leaves crowded; costa excurrent in yellowish cuspidate point (0.1−)0.2–0.6 mm long, adaxial cells in upper part of leaf rectangular, in section not or only slightly inflated; upper cells of lamina 10–21 × 21–31 μm, smooth or with 2(−3) papillae per cell. Setae straight or rarely arcuate; capsules immersed or rarely laterally emergent; spores with rounded or truncate papillae. n = 21, 26∗ , 42, 52. Disturbed soil in fields, gardens, grassland, on waste ground, banks, woodland rides. Lowland. Very common in England, much of Wales and E. Scotland, rare elsewhere, extending north to Orkney, occasional in Ireland. 99, H34, C. GB938 + 70∗ , IR47 + 9∗ , C8. Circumpolar Southern-temperate. Europe to 64◦ N, Turkey, Asia, Madeira, Canary Islands Algeria, Morocco, N. America, Ecuador. Var. papillosum (Lindb.) Roth, Eur. Laubm., 1904 (Fig. 113) Phascum cuspidatum ssp. papillosum (Lindb.) Guerra & Ros, Tortula acaulon var. papillosa (Lindb.) R. H. Zander Plants as in var. cuspidatum. Adaxial cells of costa in upper part of leaf quadrate or shortly rectangular, strongly papillose, inflated and sometimes forming a pad on adaxial side of costa; cells in upper part of leaf papillose, 9–15 × 11–30 μm. Spores spinosely papillose. Lowland. Very rare, W. Cornwall, Stafford, Hereford, Nottingham, old records from Merioneth and Antrim. 5, H1. Belgium, Denmark, France, Germany, Italy, the Netherlands, Portugal, Spain, Sweden. Var. piliferum (Hedw.) Hook. & Taylor, Muscol. Brit., 1818 Tortula acaulon var. pilifera (Hedw.) R. H. Zander

(Fig. 113)

Similar to var. cuspidatum but costa excurrent in slightly flexuose hyaline point, 0.6–1.4 mm long. Capsules immersed. n = 27. On open disturbed usually basic soil in turf, on cliffs, banks, edges of paths, stony ground, in dune-slacks. Lowland. Rare, mainly in coastal localities from Cornwall east to Kent and north to Caithness, Guernsey. 31, C. GB35 + 14∗ , C1. Europe north to southern Scandinavia, Caucasus, Turkey, Iran, N. Africa, N. America.

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Var. schreberianum (Dicks.) Brid., Muscol. Recent., 1802 (Fig. 113) P. cuspidatum var. maximum auct., Tortula acaulon var. schreberiana (Dicks.) R. H. Zander Plants 4.5–9.0 mm high. Stems simple below, branched above. Leaves as in var. acaulon, lower distant, upper erect to erect-patent. Capsules immersed. On disturbed soil in fields, on banks, waste ground. Lowland. Rare, scattered localities from S. Devon, N. Somerset and Surrey north to Durham. 16. Rare in Europe, N. Africa, N. America, Antarctica. A very variable species but much of the variation is continuous and many of the infraspecific taxa described in the past are based on arbitrary and unsatisfactory characters. In the British Isles the varieties described above appear sufficiently distinct to merit recognition although experimental studies are required to determine their status. The characters given in Dixon & Jameson (1924) for the varieties of P. cuspidatum are unsatisfactory; the only reliable character of var. piliferum is the longly excurrent costa. The plant referred to as var. curvisetum Nees & Hornsch. is not worth maintaining as the main distinguishing feature, the curved seta, is not infrequently encountered in all the forms of P. cuspidatum. Var. papillosum was raised to subspecific status by Guerra et al. (Crypt. Bryol. Lich´en. 12, 379–423, 1991) and was recorded by them from Angus, although this record has not been confirmed. The above description and key characters of var. papillosum have been taken from that paper. However, the differences between var. papillosum and var. cuspidatum are not clear cut and do not correlate and I consider that the taxon only merits varietal status. For the occurrence of var. papillosum in Britain see T. L. Blockeel, Bull. Br. Bryol. Soc. 65, 59–60, 1995.

¨ 67 POTTIA (RCHB.) FURNR., FLORA, 1823 Paroicous or occasionally synoicous. Small scattered or gregarious plants. Stems very short, with or without central strand; sclerodermis and hyalodermis absent. Axillary hairs 3–6 cells long. Leaves appressed when dry, spreading when moist, lanceolate to ovate, acute; margins recurved; costa usually excurrent, 3–4(−6) cells wide on adaxial side, cells ± quadrate, in section with abaxial stereid band; basal cells rectangular, cells above quadrate, papillose, papillae usually simple, marginal cells often less papillose and more incrassate. Perichaetial leaves similar in shape to but larger than stem leaves. Setae short, straight; capsules exserted, shortly cylindrical to ellipsoid or turbinate, dehiscent; lid conical, peristome teeth rudimentary to well developed. Laminal KOH colour reaction red. Probably only two European species. Derivation: named after the German botanist J. F. Pott (1738–1805). The descriptions of the two species are modified from those by D. F. Chamberlain in the first edition of this book, in the light of information in the two papers referred to in the footnote to P. starkeana.

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Fig. 114 1–5, Pottia starkeana: 1, upper leaf (×40); 2, cells from upper part of leaf (×430); 3, capsule (×20); 4, capsule mouth (×450); 5, spore (×800). 6–11, P. davalliana: 6, plants (×10); 7, upper leaves (×40); 8, cells from upper part of leaves of different plants (×450); 9, capsule (×20); 10, capsule mouths from different plants (×450); 11, spores from different plants (×800).

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Zander (1993) includes these two species of Pottia in Microbryum but J. Guerra & M. J. Cano (J. Bryol. 22, 91–7, 2000) provide sound reasons for separating the two genera and I have followed them.

1 Spores with warty protuberances or ridges or vermiform ornamentations (Fig. 115, 1–6) 1. P. starkeana Spores with dense papilla-like or spiny processes or a mixture of protuberances and warts or ± smooth 2 2 Spores with dense papilla-like or spinose processes (Fig. 115, 7–18) 2. P davalliana Spores with a mixture of protuberances and processes or ± smooth (Fig. 115, 19–22) Probable hybrids ¨ Hal., Syn. Musc. Eur. Musc. Frond., 1849 1 P. starkeana (Hedw.) Mull. (Figs. 114, 115) Microbryum starkeanum (Hedw.) R. H. Zander, P. starkeana var. brachyodus ¨ Hal. (Bruch & Schimp.) Mull. Autoicous. Very small gregarious ephemeral plants, 1–2 mm high. Leaves ovatelanceolate, 2.0–4.5 times as long as wide, acute; margins recurved; costa percurrent or excurrent to c. 175 μm; upper cells quadrate, thick-walled, papillose, (9−)10–12(−18) μm wide. Setae 1–4 mm long; capsules ellipsoid, usually widest at about middle with (1−)2–4 rows thickened cells below constricted mouth; peristome absent to well developed; lid conical to mamillate; annulus absent; spores 19–42 μm, with rounded protuberances, low ridges or vermiform ornamentations; calyptrae scabrous or occasionally smooth. Capsules common, winter, spring, rarely early summer. n = 26. On disturbed shallow soil on cliffs, walls, banks, by roads and tracks, woodland rides, in grassland, fields, on basic substrates. Lowland. Occasional in coastal areas, rare inland, in southern England and Wales, rare elsewhere and extending north to Angus and Kintyre, very rare in Ireland and seen recently only in Dublin. 35, H6, C. GB59 + 30∗ , IR1 + 5∗ , C3 + 2∗ . Submediterranean-Subatlantic. Europe north to S. Sweden, Turkey, Cyprus, Madeira, Canary Islands, N. Africa, N. America, Australia and New Zealand (introduced?). The taxonomy of the Pottia starkeana aggregate, including this and P. davalliana has proved very problematical for many years. Dixon & Jameson (1924) recognised four species and one variety and D. F. Chamberlain, in the first edition of this book, two species, three ´ & M. J. Cano (Pl. Syst. Evol. subspecies and one variety. R. M. Ros, J. Guerra, J. S. Carion 199, 153–65, 1996), after a detailed study of the various taxa concerned, concluded that spore morphology is the only character of taxonomic value and that the various taxa previously recognised constitute just two species. These can only be separated on the basis of spore morphology and even between these intermediates occur (Fig. 115) which may be of hybrid origin. These intermediate spores may be smooth or with weak protuberances or

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Fig. 115 Light micrographs of spores. 1–6, spores of Pottia starkeana; 7–11, spores from plants of P. davalliana with well developed peristomes; 12–18, spores from plants of P. davalliana with rudimentary or no peristomes; 19–22, spores of an intermediate type. Scale = 10 μm. I am indebted to Dr Rosa M. Ros, University of Murcia, Spain for these micrographs.

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ornamentations or sparse spines. The key to these two species is modified from that of the ´ R. M. Ros & J. Guerra, authors quoted above. Three is also an earlier paper (J. S. Carion, Nova Hedwigia 56, 89–112, 1993) discussing the correlation, or rather lack of correlation, between spore morphology and development of the peristome. Whether the two species should be maintained as separate taxa is very much open to question.

2 P. davalliana (Sm.) C. E. O. Jensen, Danmarks Mosser, 1923 (Figs. 114, 115) Microbryum davallianum (Sm.) R. H. Zander, P. commutata Limpr., P. minutula ¨ ¨ (Schwagr.) Furnr., P. starkeana ssp. commutata (Limpr.) D. F. Chamb., ¨ P. starkeana ssp. conica (Schwagr.) D. F. Chamb., P. starkeana ssp. minutula ¨ (Schwagr.) D. F. Chamb. Autoicous. Very small gregarious ephemeral plants. Leaves ovate-lanceolate, 2.0–4.5 times as long as wide; margins recurved; costa excurrent 10–200 (−280) μm; upper cells (9−)13–16(−21) μm wide, moderately papillose. Setae 1.0–2.5 mm long; capsules narrowly cylindrical to turbinate, widest at or slightly constricted at mouth, with 1–3 rows thin- or thick-walled cells below mouth; lid conical or mamillate; peristome teeth absent or rudimentary and up to 40 μm long; spores (22−)31–40(−42) μm, with papilla-like or spinose processes to c. 4 μm long. Capsules common, winter to summer. n = 26, 27 + m∗ , 28, 30. On disturbed shallow soil on cliffs, in fields, quarries, grassland, on woodland rides, by paths and among rocks, on basic substrates. Common in S. E. England, occasional elsewhere in England and Wales, very rare in the north, extending to Orkney, rare to occasional in Ireland. 73, H13, C. GB354 + 146∗ , IR21 + 16∗ , C1 + 1∗ . Submediterranean-Subatlantic. Europe north to Fennoscandia, Turkey, Cyprus, Canary Islands, N. Africa, N. America, Australasia.

68 MICROBRYUM SCHIMP., SYN. MUSC. EUR., 1860 Paroicous or occasionally synoicous. Small scattered or gregarious plants. Stems very short, with or without central strand; sclerodermis and hyalodermis absent. Axillary hairs 3–6 cells long. Leaves appressed when dry, spreading when moist, lanceolate to ovate, acute; margins recurved; costa usually excurrent, 3–4(−6) cells wide on adaxial side, cells ± quadrate, in section with abaxial stereid band; basal cells rectangular, cells above quadrate, papillose, papillae usually simple, marginal cells often less papillose and more incrassate. Perichaetial leaves similar in shape to but larger than stem leaves. Setae very short; capsules immersed or exserted, ovoid, cleistocarpous. Laminal KOH colour reaction red. Five European species, occurring especially in drier regions. Derivation: meaning small Bryum.

1 Setae 70–100 μm long, capsules immersed Setae 0.5–1.5 mm long, capsules exserted

3. M. floerkeanum 2

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2 Setae straight, capsules erect, exserted above perichaetial leaves 1. M. rectum Setae cygneous, capsules laterally exserted, horizontal or pendulous 2. M. curvicolle 1 M. rectum (With.) R. H. Zander, Bull. Buffalo Soc. Nat. Sci., 1993 Pottia recta (With.) Mitt.

(Fig. 116)

D. F. Chamberlain

Paroicous. Very small ephemeral gregarious plants. Leaves lanceolate, 2–3 times as long as wide, acute; margins recurved, entire; costa excurrent 50–130 μm; upper cells quadrate, 9–12(−15) μm wide, strongly papillose. Setae 0.6–1.0 mm long; capsules. spherical, cleistocarpous or with semideciduous apiculate lid, with 1–2 rows thickened cells at base of lid; peristome absent; spores with long spines, 23–30 μm; calyptrae rough. n = 26∗ . Capsules common, winter, spring. On soil in turf, on cliffs, banks, by tracks, in quarries, on basic substrates. Lowland. Occasional to frequent in the southern half of England, rare to occasional in Wales and northern England, rare in Scotland, extending north to Orkney, rare in Ireland. 60, H13, C. GB205 + 43∗ , IR8 + 5∗ , C1∗ . Mediterranean-Atlantic. C. and S. Europe, Caucasus, Turkey, Algeria, Morocco. Rhizoidal gemmae, indistinguishable from those of Tortula lanceola, have been reported from France (T. Arts, Lindbergia 13, 130–2, 1987).

2 M. curvicolle (Hedw.) R. H. Zander, Bull Buffalo Soc. Nat. Sci., 1993 (Fig. 116) Phascum curvicolle Hedw. Paroicous or synoicous. Ephemeral greenish to brownish gregarious or scattered plants, 1.5–3.0 mm high. Lower leaves patent, upper and perichaetial leaves erect-patent when moist, lower oblong-lanceolate, upper larger, narrowly lanceolate, acuminate; margins recurved, entire or sometimes papillosecrenulate above; costa weak below, strong above, excurrent in cuspidate point, 100–300 μm long; basal cells rectangular, cells in mid-leaf quadrate-rectangular to quadrate-hexagonal, thin-walled, strongly papillose, opaque, 12–16 μm wide, towards apex irregularly quadrate-hexagonal to rounded-hexagonal. Setae cygneous, 0.5–1.5 mm long; capsules laterally exserted, cleistocarpous, horizontal to pendulous, ovoid with stout blunt oblique apiculus; spores 24–28 μm; calyptrae cucullate. Capsules common, autumn to spring. On bare soil in chalk and limestone grassland, quarries, occasionally in stubble fields. Lowland. Frequent on the chalk in southern England, rare elsewhere and very rare in Scotland, extending north to E. Ross, W. Galway (old record), Dublin. 50, H2. GB104 + 28∗ , IR2∗ . Submediterranean-Subatlantic. S., W. and C. Europe, north to southern Scandinavia, Turkey, Algeria, Tunisia.

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Fig. 116 1–2, Microbryum curvicolle: 1, plant (×25); 2, leaves (×40). 3–5, M. floerkeanum: 3, plant (×25); 4, leaf (×65); 5, capsule (×65). 6–9, M. rectum: 6, plant (×20); 7, leaf (×40); 8, leaf apex (×80); 9, cells from upper part of leaf. (×340). 10–14, Hennediella heimii: 10, plant (×10); 11, leaf (×20); 12, leaf apex (×40); 13, cells from upper part of leaf (×340); 14, capsule (×20).

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3 M. floerkeanum (F. Weber & D. Mohr) Schimp., Syn. Musc. Eur., 1860 (Fig. 116) Phascum floerkeanum F. Weber & D. Mohr Paroicous. Ephemeral reddish green gregarious or scattered plants, 0.6–1.2 mm high. Lower leaves spreading, upper and perichaetial leaves erect-patent, concave, ovate, acuminate; margins plane or narrowly recurved, entire; costa reddish brown, weak below, strong above, excurrent in cuspidate point; basal cells lax, rectangular-hexagonal, cells above quadrate, hexagonal to rhomboidal, finely papillose on abaxial side, 12–16 μm wide in mid-leaf, towards apex smaller, ± hexagonal. Setae straight, very short, 70–100 μm long; capsules immersed but not concealed by perichaetial leaves, cleistocarpous, subglobose with blunt apiculus, symmetrical; spores 15–25 μm; calyptrae subcucullate. Capsules common, August to October. On bare soil in arable fields, more rarely in grassland or quarries, on chalk, rarely on limestone terrain. Lowland. Frequent on the chalk in England, very rare elsewhere, extending north to Yorkshire and Durham. 32. GB62 + 21∗ . European Temperate. Europe north to southern Fennoscandia, Turkey, Algeria, N. America. 69 HENNEDIELLA PARIS, INDEX BRYOL., 1896 Dioicous or monoicous. Plants forming cushions or turfs. Stems with central strand, sclerodermis and hyalodermis absent. Leaves somewhat incurved when dry, spreading or recurved when moist, narrowly lanceolate to ovate, lingulate or spathulate, acute; margins usually plane, often dentate above; costa percurrent or shortly excurrent, adaxial cells in 4–5 rows, quadrate or shortly rectangular, in section with single stereid band; basal cells rectangular, cells above quadrate or hexagonal, papillose, marginal cells longer, narrower, less papillose or smooth, forming border. Perichaetial leaves larger than stem leaves. Setae short to long; capsules ovoid to cylindrical; peristome absent, rudimentary or of 32 filiform teeth; calyptrae cucullate. Laminal KOH reaction red. A ± world-wide genus of c. 20 species. Derivation: named after the Scottish algologist Roger Hennedy (1809–1877).

1 Leaf cells slightly papillose, pellucid, marginal cells not differentiated, rhizoidal gemmae lacking 3. H. heimii Leaf cells strongly papillose, opaque, marginal cells elongate, pellucid, rhizoidal gemmae usually present 2 2 Leaves obtuse and apiculate, apiculus 25–75 μm long, mid-leaf cells 12–18 × 15–2 μm, cells towards apex usually 10–15(−24) μm wide 1. H. stanfordensis Leaves acute with apiculus 100–150 μm long, mid-leaf cells 15–20 × 25–35 μm, cells towards apex 10–25 μm wide 2. H. macrophylla

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1 H. stanfordensis (Steere) Blockeel, J. Bryol., 1990 (Fig. 117) Hyophila stanfordensis (Steere) A. J. E. Sm. & H. Whitehouse, Tortula stanfordensis Steere Dioicous. Yellowish green or green patches or scattered plants, 2–7 mm high. Leaves somewhat incurved when dry, spreading when moist and forming a flat rosette, to 2.5 mm long, lingulate to spathulate, in small plants ovate, obtuse and apiculate, apiculus 25–75 μm long; margins plane, bordered nearly to apex, irregularly toothed near apex; costa excurrent in small apiculus, adaxial cells quadrate; basal cells rectangular, hyaline, 15–20 × 65–95 μm, cells above rectangular, becoming quadrate, strongly papillose, opaque, in mid-leaf 12–18 × 15–25 μm, near apex 10–15(−24) μm wide, 2–4 marginal rows elongate, pellucid, forming distinct border. Pale brown irregularly ovoid rhizoidal gemmae, 30–60 × 50–100 μm, with protuberant cells, always present. Only 5 immature sporophytes have ever been seen. n = 13∗ . On sheltered footpaths, stream and river banks and soil on magnesian limestone ledges, very rarely in arable fields. Lowland. Rare or locally occasional, W. Cornwall, E. Sussex, E. Kent, E. Suffolk, Cambridge, banks of Rivers Severn, Teme, Wye and Dee, N. E. England, Peebles, E. and Mid Lothian, Dublin. 25, H1. GB63, IR1. European Southern-temperate. France, Greece, California, Australia. For differences from H. macrophylla see footnote to that species. Most populations of H. stanfordensis are female only. The species has only once been found with capsules (immature) in the British Isles (the only known sporophytes), and the gametophytes bearing them, although typical of H. stanfordensis, were apparently autoicous. H. stanfordensis has been found to be relatively widely distributed in Britain since its discovery in Cornwall in 1958 and is known also from France, Greece, California and Australia. It almost certainly occurs elsewhere but is likely to have been overlooked because of its small size and occurrence in what are regarded as bryologically unpromising habitats. As the species is so widespread in Britain and frequently occurs in habitats where it is unlikely to have been introduced, it is very probable that it is native, contrary to the commonly held view that it is an introduction from N. America or Australia. For an account of H. stanfordensis and its discovery in Cornwall see H. L. K. Whitehouse, Trans. Br. Bryol. Soc. 4, 84–94, 1961.

2 H. macrophylla (R. M. Br.) Paris, Index Bryol., 1896 Tortula brevis H. Whitehouse & M. E. Newton

(Fig. 117)

Autoicous or occasionally synoicous. Bright green patches or tufts, 2–25 mm high. Leaves incurved when dry, patent when moist, to 2.8(−4.0) mm long, spathulate, acute and apiculate, apiculus 100–150 μm long; margins bordered, toothed towards apex; costa percurrent, adaxial cells quadrate; basal cells rectangular, thinwalled, hyaline, 20–35 × 80–100 μm, cells above rectangular, strongly papillose, opaque, in upper part of leaf quadrate, cells in mid-leaf 15–20 × 25–35 μm, cells in upper part of leaf 10–25 μm wide, marginal cells elongate, pellucid, forming

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Fig. 117 1–4, Hennediella stanfordensis: 1, leaves; 2, marginal cells at widest part of leaf; 3, leaf apex; 4, rhizoidal gemmae (×190). 5–8, H. macrophylla: 5, leaves; 6, marginal cells at widest part of leaf; 7, leaf apex; 8, capsules (×10). Leaves ×22.5, cells ×280.

69 Hennediella

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distinct border. Brown multicellular, irregularly shaped rhizoidal gemmae present; gemmae consisting of uniseriate row of thick-walled cells occasionally present on adaxial surface of leaves. Setae very stout, c. 2 mm long; capsules slightly inclined, narrowly ellipsoid; peristome lacking; lid rostrate; spores 20–22 μm. Capsules frequent, May, June. n = 26∗ , 52∗ . Suboceanic Temperate. Rare to occasional in two areas: in S. E. England and in Northumberland and S. E. Scotland, I. of Wight. 17. GB30. Tierra del Fuego, New Zealand. In their original description H. L. K. Whitehouse & M. E. Newton (J. Bryol. 15, 83–99, 1988) say that H. stanfordensis differs from H. macrophylla in its relatively narrower, obtuse, more shortly apiculate leaves with smaller cells. However, H. macrophylla is a variable plant and forms occur with relatively narrower leaves and/or smaller leaf cells. Also, occasional plants of H. stanfordensis have cells 12–20(−24) μm wide in the upper part of the leaf and it is evident that the species are not as distinct as was originally thought. Whether H. stanfordensis and H. macrophylla can be maintained as separate species remains to be seen (see T. L. Blockeel, J. Bryol. 16, 187–92 for a discussion of this). Although H. macrophylla is known elsewhere only from the Southern Hemisphere there is no reason to consider that it is an introduced species in Great Britain. It occurs in natural habitats and is very possible that the two groups of populations in Britain arose as a consequence of polyploidy on two occasions in H. stanfordensis. That the haploid has not been seen in New Zealand or Tierra del Fuego, where H. macrophylla is found, does not mean that it does not occur there.

3 H. heimii (Hedw.) R. H. Zander, Bull. Buffalo Soc. Nat. Sci., 1993 ¨ Desmatodon heimii (Hedw.) Mitt., Pottia heimii (Hedw.) Furnr.

(Fig. 116)

D. F. Chamberlain

Autoicous, rarely synoicous. Plants ephemeral. Leaves narrowly oblonglanceolate, 3–5 times as long as wide, acute; margins plane, toothed or entire towards apex; costa percurrent to excurrent to 100 μm; upper cells quadrate, thickwalled, faintly papillose, pellucid, 13.0–21.5 μm wide. Setae 5–9 mm long; capsules obloid, 1.00–1.95 × 0.7–1.0 mm, with 2–4 rows thickened cells below slightly constricted mouth; lid rostrate, remaining attached to columella, and persisting for some time after dehiscence; annulus and peristome absent; spores minutely to coarsely papillose, 29–34 μm; calyptrae smooth. Capsules common, all year but mainly spring to early summer. n = 26∗ . Earth-covered rocks, bare patches of soil and in upper reaches of salt-marshes. Lowland. Frequent in coastal areas, very rare inland. 74, 18, C. GB210 + 67∗ , IR11 + 9∗ , C4 + 2∗ . Mediterranean-Atlantic. Circumpolar Boreo-temperate. Europe north to Svalbard, Faeroes, Iceland, N. and C. America, Caribbean. H. heimii may usually be easily distinguished from species of Tortula section Pottia, and from Pottia and Microbryum species by the persistent lid and toothed leaves.

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16 Pottiaceae

¨ 70 ACAULON MULL. HAL., BOT. ZEIT., 1847 Dioicous or autoicous. Plants small, bud-like. Stems very short, without central strand, sclerodermis or hyalodermis. Leaves ± imbricate, convolute or not, concave, sometimes strongly keeled; margins plane or recurved, entire or toothed; costa ending below apex to excurrent, adaxially 3–4 cells wide, cells elongate, in section with abaxial stereid band, sometimes with 2 lamellae on adaxial side; basal cells rectangular, cells above various in shape, rectangular to rhomboidal or quadrate, smaller towards margins and apex, smooth or papillose. Setae very short, straight or curved; capsules immersed, globose, with or without small apiculus, cleistocarpous; calyptrae small, conical. Laminal KOH reaction red. A small genus of about 15 species occurring in Europe, W. Asia, N. Africa, America, Australasia, Hawaii. Derivation: meaning without a stem.

Upper leaves convolute, plants rounded when viewed from above, setae straight, capsules erect 1. A. muticum Upper leaves barely overlapping, plants ± triangular when viewed from above, setae curved, capsules inclined 2. A. triquetrum ¨ Hal., Bot. Zeit., 1847 1 A. muticum (Schrad. ex Hedw.) Mull. A. minus (Hook. & Taylor) A. Jaeger Autoicous or dioicous. Minute ephemeral pale green gregarious or scattered plants, to 2 mm high. Lower leaves patent, upper erect, convolute, partially or completely concealing capsules when viewed from above, concave, ovate, acute or obtuse with reflexed apiculus; margins plane, toothed towards apex; costa ending below apex to excurrent in apiculus; basal cells irregularly rectangular, cells in mid-leaf narrowly rhomboidal to hexagonal, 14–30 μm wide, mostly 1–3 times as long as wide, narrower towards margins, shorter near apex. Setae c. 120 μm long, straight; capsules immersed, erect, globose, cleistocarpous, with small blunt apiculus; spores spherical or ovoid, granulose or spinulose. Capsules common, autumn to spring. Spores finely granulose Spores spinulose

var. muticum var. meditaerraneum

Var. muticum (Fig. 118) Spores granulose, 30–50 μm. n = 26. On usually neutral well drained bare soil in stubble fields, gravel pits, on banks and roadsides. Lowland. Occasional throughout much of England, rare in Wales, very rare in Scotland, extending north to E. Ross, very rare in Ireland and not seen recently. 72, H7, C. GB102 + 94∗ , IR7∗ , C2. European Temperate. Europe north to Fennoscandia, W. and C. Asia, Siberia, Azores, Gran Canaria, Tenerife, Algeria, Morocco, N. America, Australia.

70 Acaulon

377

Fig. 118 1–5, Acaulon muticum var. muticum: 1, plant (×20); 2, leaves (×40); 3, cells near leaf apex from different plants; 4, mid-leaf cells from different plants; 5, capsule. 6–8, A. triquetrum: 6, leaves (×65); 7, mid-leaf cells; 8, capsule. Cells ×420, capsules ×65.

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16 Pottiaceae

´ Var. mediterraneum (Limpr.) Sergio, Bol. Soc. Brot., 1972 Spores c. 30 μm, spinulose, spinules 2–3 μm high. Capsules common, winter. On and by paths and tracks, bare soil in turf, fields and on cliff tops. Occasional in Cornwall, very rare elsewhere, Cornwall, S. Devon, S. Somerset. 4. GB8 + 1∗ . Crete, France, Greece, Italy, Portugal, Sardinia, Spain, Sweden, Turkey, Australia. Var. mediterraneum is variously treated as a species or a variety of or synonymous with A. muticum. The only known difference between the type and var. mediterraneum is spore ornamentation, although the latter has a more southerly distribution. For a discussion of the taxonomic status of var. mediterraneum see D. T. Holyoak, Bull. Br. Bryol. Soc. in press. It has been shown that there is no discontinuity in variation in morphological and spore characters between A. muticum and A. minus, and the latter cannot be maintained as a distinct taxon (see M. O. Hill, J. Bryol. 12, 11–14, 1982).

¨ Hal., Bot. Zeit., 1847 2 A. triquetrum (Spruce) Mull. (Fig. 118) Minute ephemeral green to yellowish brown gregarious or scattered plants, to 1.5 mm high. Upper leaves imbricate but scarcely overlapping, usually the three uppermost strongly keeled so that plant appears ± triangular when viewed from above. Leaves ovate, obtuse to acute; margins narrowly recurved above with a few sharp teeth near apex; costa excurrent in reflexed apiculus; basal cells shortly rectangular, cells in mid-leaf quadrate-rectangular to trapezoid, 12–20 μm wide, shorter towards apex. Setae arcuate, thin, fragile; capsules inclined, globose, cleistocarpous, with small blunt apiculus; spores finely papillose, c. 30 μm. Capsules common, winter. On bare chalky ground on coastal cliffs and banks. Lowland. Very rare, S. Devon (old record), Dorset, I. of Wight, E. Sussex. 4. GB4 + 6∗ . Submediterranean-Subatlantic. Europe from the Mediterranean north to Belgium and Germany, Turkey, Fuerteventura, Tenerife, Algeria, Morocco, Australia. This species is considered endangered in the Red List of British mosses and is a protected plant under the Wildlife and Countryside Act.

¨ 71 LEPTOPHASCUM (MULL. HAL.) J. GUERRA & M. J. CANO, J. BRYOL., 2000 A monotypic genus with the characters of the species. Derivation: meaning slender Phascum.

¨ Hal.) J. Guerra & M. J. Cano, J. Bryol., 2000 1 L. leptophyllum (Mull. (Fig. 119) ¨ Hal.) R. H. Zander, Phascum leptophyllum Mull. ¨ Hal., Chenia leptophylla (Mull. Tortula rhizophylla (Sakurai) Z. Iwats. & M. Saito, T. vectensis E. F. Warb. & Crundw. Ephemeral green or brownish green gregarious or scattered plants, to 3 mm high. Leaves incurved, contorted when dry, patent to widely spreading with reflexed tips

71 Leptophascum

379

Fig. 119 1–3, Leptophascum leptophyllum: 1, leaves; 2, cells from widest part of leaf; 3, rhizoidal gemmae (×250). 4–5, Syntrichia norvegica: 4, leaf; 5, cells from widest part of leaf. 6–11, S. ruralis var. ruralis: 6, leaf; 7, leaf apex (×70); 8, costa section (×175); 9, basal cells; 10, cells from widest part of leaf; 11, capsule (×10). 12, S. ruralis var. ruraliformis: leaf. Leaves ×25, cells ×280.

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16 Pottiaceae

when moist, spathulate, rapidly narrowed to acute to acuminate apex; margins plane, subcrenulate above; costa excurrent in short reflexed apiculus; cells collenchymatous but not incrassate, basal shortly rectangular, cells above irregularly hexagonal with brownish walls smooth, pellucid, very variable in size, 14–30 μm wide at widest part of leaf, smaller towards apex. Irregular ± elongate brownish rhizoidal gemmae, 70–190 × 30–125 μm, abundant. Setae very short, 0.1–0.2 mm long, straight; capsules immersed, ± subspherical, cleistocarpous, with longly rostrate oblique beak; spores 15–20 μm. Capsules unknown in Britain. On basic to acidic soil in stubble fields, on gravelly soil and cliff paths. Lowland. Very rare, Scilly Isles, W. Cornwall, I. of Wight. 2. GB3. Oceanic Southern-temperate. Germany, Italy, Spain, India, China, Japan, New Guinea, Azores, Canary Islands., east and southern Africa, N. and S. America, Easter Is., Hawaii. It seems unlikely that this plant is an introduction as it occurs in widely scattered localities ± throughout the world. Its small size and frequent lack of sporophytes mean that it is likely to be passed over for sterile Tortula sect. Pottia, Pottia or Mictobryum species. It differs in the morphology of the abundant rhizoidal gemmae and, in Britain, absence of capsules. In cultivation the plants from the Isle of Wight proved to be female. For the occurrence of this plant in Britain see E. F. Warburg & A. C. Crundwell, Trans. Br. Bryol. Soc. 4, 763–6, 1965, and for a more detailed account, from which the above description of sporophytes was taken, see T. Arts & P. Sollman, Lindbergia 17, 20–7, 1991. For the reasons for placing L. leptophyllum in its own genus see J. Guerra & M. J. Cano, J. Bryol. 22, 91–97, 2000.

72 SYNTRICHIA BRID., J. BOT. (SCHRADER), 1801 Dioicous, autoicous or synoicous. Plants often large, forming cushions or turfs. Stems with or without central strand. Leaves ± appressed when dry, spreading to squarrose when moist, narrowly lingulate to broadly spathulate; margins plane or recurved, usually entire; costa stout, ending below apex to longly excurrent in hyaline usually denticulate point, 2–4 cells wide adaxially, cells rounded-quadrate, papillose, abaxial cells elongate, papillose to dentate, in section with crescent-shaped abaxial stereid band; basal cells sharply differentiated from cells above, narrowly rectangular, thin-walled, hyaline, cells above rounded-quadrate, papillose. Vegetative propagules sometimes present. Perichaetial leaves ± similar to stem leaves. Setae long; capsules cylindrical, often slightly curved; peristome teeth filiform, papillose, spirally coiled; lid longly rostrate; calyptrae cucullate, smooth. Laminal KOH reaction red. About 90 species world-wide. Derivation: meaning joined hair, referring to the fusion of the peristome teeth below.

1 Costa excurrent in usually hyaline hair-point 2 Costa ending in or below apex 8 2 Leaf margins incurved or involute above, 2–several-celled gemmae on adaxial side of costa 7. S. papillosa

72 Syntrichia

381

Leaf margins plane to recurved from base to apex, gemmae lacking 3 3 Hair-points reddish except sometimes at tip 2. S. norvegica Hair-points hyaline except sometimes at base 4 4 Leaves not contracted at or below middle, margins recurved ± from base to apex 1. S. ruralis Leaves contracted at or below middle, margins plane to recurved to 3 /4 way up leaf 5 5 Hair-points smooth or sparsely and opaquely denticulate, gemmae resembling minute leaves sometimes present 6. S. laevipila Hair-points denticulate or spinulose, gemmae lacking 6 6 Plants 0.2–2.0(−3.0) cm high, basal cells in lower part of leaves rectangular, 20–40 μm long 5. S. virescens Plants 1–4 cm high, basal cells narrowly rectangular, 50−80 μm long 7 7 Dioicous, leaf cells 8–10(−12) μm wide at widest part of leaf 3. S. intermedia Synoicous, cells (10−)12–20(−22) μm wide 4. S. princeps 8 Leaf apices rounded, emarginate or not, small ± spherical gemmae usually present on adaxial side of leaves, rhizoidal gemmae lacking, plants often silt-encrusted 8. S. latifolia Leaf apices obtuse, apiculate or not, leaf gemmae lacking, rhizoidal gemmae present, plants not silt-encrusted, very rare 9. S. amplexa 1 S. ruralis (Hedw.) F. Weber & D. Mohr, Index Musc. Pl. Crypt., 1803 Dioicous. Loose cushions or turfs, brownish when dry, golden green above, reddish below when moist, 1–8 cm high. Stems without central strand. Leaves appressed, ± twisted when dry, squarrose when moist, lingulate, not or hardly constricted at or below middle, apex rounded and sometimes emarginated to obtuse or tapering into hair-point; margins strongly recurved ± from base to apex, papillose-crenulate; costa stout, brownish, excurrent in denticulate to spinulose hyaline hair-point to as long as lamina; cells in lower part of leaf rectangular, hyaline, shorter and narrower towards margins, above hexagonal, strongly papillose, opaque, 12–16 μm wide at widest part of leaf. Capsules cylindrical, slightly curved, peristome spirally coiled, tubular in lower 2 /3 –3 /4 ; spores 10–12 μm. Capsules rare, spring, early summer. n = 12, 26. Leaf apices obtuse or rounded, not tapering into hyaline point var. ruralis Leaf apices acute, tapering into hyaline point var. ruraliformis Var. ruralis (Fig. 119) S. calcicola J. J. Amann, S. calcicolens (W. A. Kramer) Duell, Tortula calcicolens W. A. Kramer, T. ruralis (Hedw.) P. Gaertn. et al. Leaves lingulate, apices rounded or obtuse, sometimes emarginated. Exposed sunny walls, roof tiles, concrete, stony ground, rock outcrops, sand-dunes,

382

16 Pottiaceae

calcicole. 0–350 m. Frequent or common in England, Wales and eastern Scotland, occasional elsewhere and in Ireland. 100, H35, C. GB738 + 116∗ , IR54 + 13∗ , C5 + 1∗ . Circumpolar Wide-temperate. Europe north to Svalbard, Faeroes, Iceland, Caucasus, Turkey, Cyprus, Asia, Africa, Macaronesia, N. America, Greenland, Patagonia, Australia, Oceania. Var. ruraliformis (Besch.) Husn. Ex T. Durand, Bull. Soc. Bot. Belg., 1890 (Fig. 119) S. ruraliformis (Besch.) Cardot, Tortula ruraliformis (Besch.) Ingham, T. ruralis ssp. ruraliformis (Besch.) Dixon, T. ruralis var. arenicola Braithw. Dioicous. Lax cushions or turfs, sometimes almost buried in sand. Leaves oblonglanceolate, apices acute, tapering into hair-point. n = 13∗ . Exposed sunny situations on walls, rock outcrops, stony and sandy ground and especially sand-dunes, calcicole. Lowland. Common along coasts throughout the British Isles, occasional inland in S. England and S. Wales. 88, H19. C. GB305 + 44∗ , IR142 + 5∗ , C7. European Southern-temperate. Europe north to Scandinavia, Iceland, Caucasus, Turkey, Cyprus, Asia, Macaronesia, Algeria, western N. America. S. ruralis may be confused with S. intermedia but differs in the leaves squarrose when moist, not or hardly contracted at or below the middle and the margins recurved to near the apex. The two varieties usually differ in leaf shape and ecology, var. ruraliformis occurring most commonly on sand-dunes and rare inland whereas var. ruralis is rare on sand-dunes and common in inland habitats. However, intermediates occur and I have followed M. T. Gallego et al. (Bot. J. Linn. Soc. 138, 209–24, 2000) in their treatment of the taxa. Duell (1992) suggests that for similar reasons S. intermedia should be treated as a subspecies of S. ruralis. There is in addition another taxon, S. calcicola Amann, described as differing from S. ruralis in having erect-patent lingulate leaves with margins recurved to c. 3 /4 way up, shorter hyaline bases and cells with less dense and horseshoe-shaped papillae. Some British specimens agree with this but so many intermediates exist that S. calcicola cannot be maintained as a distinct taxon in the British Isles.

2 S. norvegica F. Weber, Arch. Syst. Naturgesch., 1804 (Fig. 119) Tortula norvegica (F. Weber) Wahlenb. ex Lindb., T. ruralis var. alpina Wahlenb. Dioicous. Lax cushions, reddish brown when dry, yellowish green above, reddish brown below when moist, 1–10 cm high. Leaves appressed, ± twisted when dry, squarrose when moist, oblong-spathulate, not or hardly constricted at or below middle, apex obtuse; margins recurved 2 /3 –3 /4 way up leaf; hair-point denticulate, reddish throughout or hyaline only at apex; cells in basal part rectangular, hyaline, cells above hexagonal, strongly papillose, opaque, 12–16(−20) μm wide at widest part of leaf. Capsules shortly cylindrical; spores 10–14 μm. Capsules unknown in Britain. n = 12 + m. In rock crevices and among boulders, strongly calcicolous. C. 1000 m. Very rare, Mid Perth, Angus, W. Inverness. 3. GB2 + 3∗ . Circumpolar

72 Syntrichia

383

Arctic-montane. Montane and northern Europe north to Svalbard, Iceland, Caucasus, Turkey, Cyprus, Asia, Madeira, N. Africa, N. America, Greenland, Mexico. This species is treated as vulnerable in the Red List of British Mosses.

3 S. intermedia Brid., Bryol. Univ., 1826 Tortula crinita (De Not.) De Not., T. intermedia (Brid.) De Not.

(Fig. 120)

Dioicous. Lax cushions, greyish brown and hoary when dry, greenish when moist, 1–4 cm high. Stems usually without a central strand. Leaves appressed, incurved or twisted when dry, erect-patent to spreading, rarely subsquarrose when moist, broadly spathulate, contracted at or below the middle, apex rounded, sometimes emarginate; margins recurved 1 /2 –2 /3 way up leaf, papillose-crenulate; costa strong, reddish, excurrent in denticulate hyaline point to 3 /4 –1 length of lamina; cells in lower part of leaf narrowly rectangular, hyaline, mostly 50–80 μm long, shorter and narrower towards margins, cells above hexagonal, papillose, opaque, 8–10(−12) μm wide at widest part of leaf. Capsules shortly cylindrical, slightly curved or not, 2–3 mm long; lower 2 /3 of peristome tubular; spores 14–16 μm. Capsules occasional, spring, summer. n = 12, 12 + m∗ , 13∗ . In usually exposed situations on limestone, concrete, walls, roof tiles, rarely on stony ground, trees and acidic rocks. 0–625 m. Frequent or common in the southern half of Britain, occasional elsewhere and extending north to Shetland, occasional in Ireland. 101, H31, C. GB736 + 89∗ , IR44 + 12∗ , C6 + 1∗ . Submediterranean-Subatlantic. Europe north to southern Scandinavia, Caucasus, Turkey, Cyprus, N. Asia, Macaronesia, N. Africa, N. and C. America. 4 S. princeps (De Not.) Mitt., J. Linn. Soc. Bot., 1859 Tortula princeps De Not.

(Fig. 120)

Synoicous. Dense spreading tufts or patches, green above, reddish below, 1–4 cm high. Stems with a central strand. Leaves in interrupted tufts on stems, flexuose, twisted when dry, patent or recurved when moist, oblong-spathulate, constricted at or below middle, apex rounded, sometimes emarginate; margins recurved to 1 /2 –3 /4 way up leaf; costa stout, reddish brown, excurrent in denticulate hyaline hair-point; cells in lower part of leaf narrowly rectangular, hyaline, shorter and narrower towards margins, cells above hexagonal, papillose, opaque, (10−)12– 20(−22) μm wide at widest part of leaf. Capsules cylindrical, slightly curved, 3.5– 4.5 mm long; spores 12–14 μm. Capsules frequent, autumn. n = 12, 24, 26, 24 + m, 26, 36 + 2m. In open situations on rock outcrops, and in crevices, cliff ledges, walls, rarely in open woodland, calcicole. 100–500 m. Rare and decreasing, widely scattered from Shropshire and Derby north to W. Sutherland, Sligo, old records from Antrim and Londonderry. 22, H3. GB15 + 18∗ , IR6∗ . European Temperate. Europe north to Scandinavia, Caucasus, Turkey, Cyprus, N. Asia, China, Canary Islands, Madeira, Algeria, N. America, Australia, New Zealand, Oceania.

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16 Pottiaceae

Fig. 120 1–5, Syntrichia intermedia: 1, leaves (×25); 2, costa section; 3, basal cells; 4, cells from widest part of leaf; 5, capsule. 6–8, S. princeps: 6, leaf (×17.5) 7, cells at widest part of leaf; 8, capsule. 9–12, S. virescens: 9, leaves (×25); 10, costa section; 11, basal cells; 12, cells at widest part of leaf. Sections ×175, cells ×280, capsules ×10.

72 Syntrichia 5 S. virescens (De Not.) Ochyra, Fragm. Florist. Geobot., 1992 T. pulvinata (Jur.) Limpr., T. virescens (De Not.) De Not.

385 (Fig. 120)

Dioicous. Dense dull green tufts or patches, 0.5–3.0 cm high. Stems in section with small central strand. Leaves twisted, incurved when dry, slightly recurved when moist, oblong-spathulate, constricted at or below middle, subacute to obtuse or rounded and almost always some emarginate; margins plane or recurved only in lower part of leaf; costa reddish brown, excurrent in denticulate hyaline hair-point 1 /4 –1 /3 length of lamina, in section with 1–2(−3) rows of abaxial stereids; basal cells rectangular, hyaline, 20–40 μm long, cells above quadrate-hexagonal, papillose, 12–16 μm wide at widest part of leaf. Capsules narrowly cylindrical, 2–3 mm long; spores 8–12 μm. Capsules very rare. On tree trunks in open situations, stones, walls, concrete, asphalt paths. Lowland. Occasional in eastern England, very rare elsewhere, from S. Wiltshire and W. Sussex north to E. Ross. 32. GB52 + 2∗ . European Temperate. Europe from Spain, Sardinia and Sicily north to C. Scandinavia, Caucasus, Turkey, Kashmir, Canary Islands, N. America. Related to S. laevipila, S. intermedia and S. ruralis but differing in its smaller size and thinner band of stereids in the costa section, this rendering the costa less prominent in side view. It differs from S. laevipila in the denticulate hair-points. For the occurrence of this species in Britain see E. F. Warburg & A. C. Crundwell, Trans. Br. Bryol. Soc. 3, 568–70, 1965.

6 S. laevipila Brid., Muscol. Recent. Suppl, 1819 (Fig. 121) ¨ Tortula laevipila (Brid.) Schwagr., T. laevipila var. laevipiliformis (De Not.) Limpr., Autoicous or dioicous. Light green or yellowish green tufts or patches, 1.0– 1.5(−3.0) cm high. Stems in section with central strand. Leaves twisted, incurved when dry, spreading to recurved when moist, broadly spathulate, constricted at or below middle, apex rounded; margins plane or recurved near middle of leaf, papillose-crenulate; costa stout, excurrent in hyaline smooth to obscurely and sparsely denticulate hair-point, 1 /4 –1 length of lamina, in section with several rows of stereid cells; cells in lower part of leaf hyaline, rectangular, narrower towards margins, cells above quadrate-hexagonal, papillose, opaque, 10–14 μm wide at widest part of leaf, 0–4 marginal rows more incrassate and pellucid, less papillose. Gemmae, in the form of minute leaves with costa, sometimes present at stem tips. Capsules cylindrical, slightly curved, 2–3 mm long; peristome tubular in lower half; spores 14–20 μm. Capsules occasional to frequent, summer, autumn. n = 12, 15, 26∗ . On trunks and branches of trees and shrubs in open situations, very rarely on rocks and walls. Lowland. Frequent or common in Wales and the southern half of England, S. E. Scotland, rare to occasional elsewhere, extending north to Caithness, occasional in Ireland. 103, H34, C. GB704 + 125∗ , IR47 + 15∗ , C7. Submediterranean-Subatlantic. Europe north to S. Sweden, Turkey, Cyprus, N. and

386

16 Pottiaceae

Fig. 121 1–6, Syntrichia laevipila: 1, leaves; 2, costa section (×125); 3, cells from widest part of leaf; 4, capsule (×10): 5, marginal cells from widest part of leaf; 6, gemmae (×45). 7–9, S. latifolia: 7, leaf; 8, cells from widest part of leaf; 9, gemmae (×175). 10–12, S. papillosa: 10, leaves; 11, cells from widest part of leaf; 12, gemmae (×175). 13–15, S. amplexa: 13, leaves; 14, marginal cells at widest part of leaf; 15, gemmae (×300). Leaves ×25, cells ×280.

72 Syntrichia

387

E. Asia, Azores, Canary Islands, Algeria, Morocco, Kenya, N. America, southern S. America, Australia, New Zealand, Antarctica. In the first edition of this flora two varieties of this species were described, var. laevipila (autoicous, often with capsules and lacking gemmae) and var. laevipiliformis (De Not.) J. Amann (dioicous, without capsules but with gemmae). Investigation of a quantity of gatherings has shown that some with capsules also have gemmae and that some sterile gatherings lack gemmae. The sex of such gatherings is uncertain. It is clear that in the light of this the two varieties cannot be maintained as separate taxa. There is a species reported from continental Europe, S. pagorum (Hedw.) J. J. Amann, and which could occur in the British Isles. It differs from S. laevipila in capsule characters and in the gemmae lacking a costa.

¨ 7 S. papillosa (Wilson) Jur., Laubmfl. Osterr.-Ung., 1882 Tortula papillosa Wilson

(Fig. 121)

Dioicous. Small dark green patches or tufts, 2–10 mm high. Leaves incurved when dry, spreading or recurved when moist, broadly ovate-spathulate, constricted below middle, apex rounded; margins inflexed above, papillose-crenulate; costa broad, strongly papillose on abaxial side above, excurrent in smooth hyaline hairpoint 1 /3 –1 /2 length of lamina; cells in lower part of leaf rectangular, hyaline, cells above quadrate-hexagonal, papillose, pellucid, 16–24 μm wide at widest part of leaf. Irregularly spherical or ovoid 2-several celled gemmae, 30–100 μm long, present on adaxial side of upper part of costa in younger leaves. Capsules known only from Australasia. n = 6 + m, 12, 24. On bark, particularly of mature trees, very rarely on rocks or walls. Lowland. Rare to occasional and decreasing in England, Wales and E. Scotland, extending north to Ross, rare in Ireland. 90, H17, C. GB165 + 202∗ , IR14 + 14∗ , C3. European Temperate. Europe north to Scandinavia, Canary Islands, Africa, N. America, Ecuador, Andes, Tierra del Fuego, Falkland Islands, Australia, Tasmania. New Zealand. 8 S. latifolia (Bruch ex Hartm.) Huebener, Muscol. Germ., 1883 Tortula latifolia Bruch ex Hartm., T. mutica Lindb.

(Fig. 121)

Dioicous. Dull or brownish green often silt-encrusted patches, to 3 cm high. Leaves ± appressed or incurved when dry, lower erect-patent, upper crowded, soft, spreading when moist, broadly spathulate, apex rounded, sometimes emarginate; margins plane or narrowly recurved below, papillose-crenulate, often eroded; costa strong, brownish, ending below apex to percurrent; cells in lower part of leaf rectangular, cells above hexagonal, papillose, pellucid, 12–16 μm wide at widest part of leaf. Small ± spherical gemmae, 24–36 μm diameter, present on adaxial surface of leaves. Capsules cylindrical, slightly curved; lower 1 /3 of peristome tubular; spores 10–12 μm. Capsules very rare, spring. n = 12. On tree boles, exposed roots, rocks and walls in flood zone of streams and rivers, rarely away from water. Lowland. Frequent or common in Wales and the southern half of

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17 Cinclidotaceae

England, becoming rarer northwards and extending to Banff, rare in Ireland. 85, H14. GB406 + 60∗ , IR8 + 11∗ . European Temperate. W. and C. Europe, extending north to S. Sweden, Turkey, Caucasus, eastern N. America. 9 S. amplexa (Lesq.) R. H. Zander, Bull. Buffalo Soc. Nat. Sci., 1993 Tortula amplexa (Lesq.) Steere

(Fig. 121)

Dioicous. Dense green tufts, reddish brown below, to 6 mm high. Leaves ± twisted when dry, spreading when moist, slightly concave, lingulate-spathulate, obtuse, apiculate or not; margins recurved below, plane, entire above; costa ending just below apex; basal cells rectangular, narrower towards margins, cells above irregularly quadrate, papillose, (13−)15–25(−28) μm wide at widest part of leaf, c. 4 marginal rows smaller, more incrassate, less papillose, forming yellowish border. Abundant, pale brown, 1–3-celled rhizoidal gemmae, 20–75 × 20–35 μm, present. Only female plants known in Britain. On disturbed clay. Lowland. Very rare, known from only a few sites in Leicester. 1. GB1. Introduced (Suboceanic Temperate). California, Washington, British Columbia. Originally discovered on modelling clay in a pottery class in Tunbridge Wells, Kent, the source of which was traced to clay pits in Leicestershire where the plant was found growing. It seems very likely that S. amplexa is an introduction from N. America. For an account of its discovery see A. G. Side & H. L. K. Whitehorse, J. Bryol. 8. 15–18, 1974, and for further information about distribution see R. Porley & N. G. Hodgetts, Bull. Br. Bryol. Soc. 65, 61–3, 1995.

17 Cinclidotaceae With the characters of the single genus. ´ 73 CINCLIDOTUS P. BEAUV., PRODR. AETHEOGAM., 1805 European species usually cladocarpous, dioicous. Robust, often aquatic plants with lateral or terminal gametangia; stems without central strand. Leaves erect or curled when dry, patent to spreading when moist, lanceolate to broadly lingulate, apex acute to rounded; margins plane or recurved, strongly thickened; costa ending below apex to excurrent, in section with two stereid bands; basal cells rectangular, cells above hexagonal, smooth or slightly papillose, marginal severalstratose. Setae short or long; capsules immersed or exserted, ellipsoid to cylindrical, ribbed when dry; peristome teeth 16, bifid into filiform smooth or papillose segments, straight or spirally coiled; calyptrae cucullate. About 10 species occurring in Europe, N. Africa, Macaronesia and N. America. Derivation: from the Greek word meaning latticed referring to the latticed peristome.

Capsules immersed, leaves often asymmetrical, acute to obtuse, margins in section with inner cells smaller and thicker-walled than outer 1. C. fontinaloides

73 Cinclidotus

389

Fig. 122 1–4, Cinclidotus fontinaloides: 1, shoot tip with sporophyte (×10); 2, leaves; 3, mid-leaf cells; 4, section of margin at middle of leaf. 5–8, C. riparius: 5, leaf; 6, mid-leaf cells; 7, section of margin at middle of leaf; 8, sporophyte (×7). Leaves ×15, cells ×420.

Capsules exserted, leaves symmetrical, apex obtuse or rounded, marginal cells ± uniform in section 2. C. riparius

1 C. fontinaloides (Hedw.) P. Beauv., Prodr. Aeth´eogam., 1805 (Fig. 122) Lax olive-green to blackish green floating or ± decumbent tufts, 2–12 cm long, stems fastigiately branched. Leaves flexuose or contorted when dry, patent and often secund when moist, oblong-lanceolate to narrowly lanceolate, frequently asymmetrical, keeled above, acute to obtuse; margins strongly thickened, plane, entire or obscurely and irregularly toothed at extreme apex, older leaves frequently eroded; costa stout, ending in apex; cells at extreme base shortly rectangular, elsewhere irregularly hexagonal, faintly papillose, 8–14 μm wide in mid-leaf; margins in section ± circular, with inner cells smaller and more incrassate than

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17 Cinclidotaceae

outer. Perichaetia usually on short lateral branches but occasionally terminal on main stems and branches. Setae very short, c. 0.5 mm long; capsules immersed, ellipsoid; lid longly rostrate, oblique, red at maturity; peristome teeth divided into purplish filiform papillose segments; spores coarsely papillose, 18–20 μm. Capsules frequent, spring, summer. n = 13∗ . On basic rocks, especially limestone and on wood by fast-flowing streams and rivers; in lowland areas usually by weirs, locks and embankment walls; abundant in Irish turloughs; usually in situations subject to periodic inundation. 0–300 m. Rare or occasional in lowland areas, frequent in upland regions. 102, H34. GB398 + 66∗ , IR128 + 6∗ . European Southerntemperate. Europe north to Scandinavia, Caucasus, Asia, China, Tibet, Madeira, Canary Islands, Tunisia, E. Africa. A very variable species some forms of which resemble C. riparius (q.v.). In habit the plant may resemble Schistidium rivulare, but it has longer and narrower leaves with strongly thickened margins, and different areolation and capsule characters. Orthotrichum rivulare differs in the rounded leaf apices, recurved margins and capsules with a double peristome with broad outer teeth.

2 C. riparius (Host ex Brid.) Arnott, Mem. Soc. Linn. Paris, 1827 (Fig. 122) Compact to lax blackish green tufts, to 5 cm high. Leaves erect, loosely appressed and sometimes slightly twisted when dry, erect-patent, often with reflexed apex when moist, ovate-elliptical to narrowly lingulate, plane above, obtuse or rounded and usually mucronate; margins strongly thickened, plane; costa percurrent or excurrent in short mucro; basal cells shortly rectangular, cells above quadrate to hexagonal, smooth or faintly papillose, often partially bistratose near margins, 8–16(−20) μm wide in mid-leaf; margins in section usually oval with all cells of ± similar size. Perichaetia terminal on short lateral branches, main stems and branches. Setae 3–6 mm long; capsules exserted, ellipsoid, straight or slightly curved; peristome teeth yellowish, smooth, spirally coiled; spores c. 20 μm. Male plants and sporophytes unknown in the British Isles. n = 13. On rocks and stonework in the flood-zone of rivers. Lowland. Very rare but locally frequent, Hereford, Worcester, Shropshire, Clare (1884). 3, H1. European Southern-temperate. Europe north to Germany and Poland, Turkey, N. Africa. The presence of this species in the British Isles has been a matter of dispute for about a century but its occurrence has recently been confirmed (see T. L. Blockeel, J. Bryol. 20, 109–19, 1998). When capsules are present C. fontinaloides and C. riparius are readily distinguished but sterile plants can only be identified with certainty by leaf margin sections. However, there is often some difference in leaf shape, with those of C. riparius tending to be elliptical or narrowly lingulate and relatively wider than the ovate-lanceolate and often asymmetrical leaves of C. fontinaloides, and the leaf apices are often obtuse or rounded and mucronate. C. riparius is usually a more compact and darker plant and the leaves are scarcely twisted when dry.

75 Ephemerum

391

18 Ephemeraceae Plants minute, annual or ephemeral, arising from persistent protonemata. Leaves forming a rosette, ovate-lanceolate to narrowly lanceolate; margins plane, dentate or entire; costa present or not; cells large, lax, ± narrowly hexagonal. Capsules immersed, ± globose, cleistocarpous or dehiscent and gymnostomous, thinwalled; spores large, (20−)40–80 μm. Three genera.

74 MICROMITRIUM AUSTIN, MUSCI APPALLACH., 1870 Autoicous. Plants minute. Leaves lanceolate; costa lacking; cells lax. Setae lacking; capsules globose, capsule wall only one cell thick, stomata absent; ring of differentiated cells delimiting rudimentary lid; calyptrae minute, persisting. About 10 mainly American species but with a few in Europe, Asia, Australia and Oceania. Derivation: referring to the minute calyptrae.

1 M. tenerum (Bruch & Schimp.) Crosby, Bryologist, 1968 Nanomitrium tenerum (Bruch & Schimp.) Lindb.

(Fig. 123)

Minute ephemeral plants arising from a usually persistent protonema. Lower leaves spreading, upper erect-patent, ovate-lanceolate to lanceolate, acuminate; margins subentire to opaquely denticulate; costa absent; cells lax, rhomboidhexagonal, 20–25 μm wide in mid-leaf. Capsules ± globose, cleistocarpous but dehiscing along a ring of differentiated cells under pressure; spores papillose, 20–30 μm. Capsules common, autumn. On mud of dried-out ponds and around reservoirs. Lowland. Very rare and sporadic, endangered because of loss of habitats. W. Sussex, Anglesey, old records from E. Sussex and W. Kent, Surrey. 5. GB3 + 7∗ . Suboceanic Temperate. Belgium, Czechoslovakia, France, Germany, N. Spain, S. Sweden, E. Asia, N. America. This is a critically endangered species in the Red List of British mosses.

75 EPHEMERUM HAMPE, FLORA, 1837 Autoicous or dioicous. Minute ephemeral plants arising from usually persistent protonemata. Leaves ± lanceolate; costa present or not; cells lax, pellucid. Setae very short; capsules immersed, cleistocarpous, ± globose or ovoid, apiculate, wall of two layers of cells, lacking ring of differentiated cells, stomata present; calyptrae not persisting. A cosmopolitan genus of about 27 species. Derivation: meaning short-lived.

1 Leaves costate Leaves ecostate

2 5

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18 Ephemeraceae

Fig. 123 1–3, Micromitrium tenerum: 1, plant (×30); 2, leaf (×85); 3, marginal cells. 4–6, Ephemerum recurvifolium: 4, plant (×20); 5, leaves (×40); 6, marginal cells. 7–9, E. sessile: 7, plant (×20); 8, leaf (×40); 9, marginal cells. 10–12, E. stellatum: 10, plant with young capsule (×20); 11, leaf (×40); 12, leaf cells. 13–15, E. cohaerens: 13, leaf (×40); 14, marginal cells; 15, capsule (×30). Cells, all from upper part of leaf, ×280.

75 Ephemerum

393

2 Costa poorly defined, upper cells spinulose papillose 4. E. spinulosum Costa well defined, cells smooth 3 3 Upper leaves lanceolate, costa ending in apex, mid-leaf cells 60–80 μm long 3. E. cohaerens Upper leaves narrowly lanceolate to linear-lanceolate, costa excurrent, mid-leaf cells 10–50 μm long 4 4 Upper leaves recurved, capsules with oblique apiculus, stomata near base of capsule only, spores ± smooth 1. E. recurvifolium Leaves erect-patent, capsules with straight apiculus, stomata scattered over whole of capsule, spores coarsely papillose 2. E. sessile 5 Leaf margins entire or denticulate, mid-leaf cells 50–90 μm long, spores ± smooth 5. E. stellatum Leaf margins spinosely dentate, mid-leaf cells 100–160 μm long, spores finely or coarsely papillose 6 6 Marginal teeth of leaves straight, spores coarsely papillose, without hyaline membrane 6. E. serratum Marginal teeth of leaves often recurved, spores finely papillose, usually surrounded by hyaline membrane 7. E. minutissimum 1 E. recurvifolium (Dicks.) Boulay, Musci de l’Est, 1872 Ephemerella recurvifolia (Dicks.) Schimp.

(Fig. 123)

Pseudodioicous. Minute ephemeral scattered plants on persistent protonemata. Leaves erect-patent, upper and perichaetial leaves recurved, narrowly lanceolate, acuminate; margins denticulate, sometimes with 1–2 coarse teeth near apex; costa well defined, excurrent; mid-leaf cells 8–14(−20) × 10–40 μm. Capsules ± globose with oblique apiculus, stomata at base of capsule only; spores ± smooth, 40–55 μm; calyptrae cucullate. Capsules common, autumn, winter. On basic clay and damp soil on woodland rides, in beech woods, fields and grassland. Lowland. Occasional from S. Devon east to Kent and north to Caernarfon, Cheshire, Durham, 33. GB48 + 13∗ . European Southern-temperate. Europe north to Sweden and Finland, Israel, Turkey, N. Africa. ¨ Hal., Syn. Musc., 1848 2 E. sessile (Bruch) Mull. Ephemerella sessilis (Bruch) Nyholm

(Fig. 123)

Pseudodioicous. Minute ephemeral scattered plants or small patches on persistent protonemata. Upper and perichaetial leaves erect-patent, narrowly lanceolate, denticulate; costa weak below, strong above, excurrent; cells in mid-leaf 10–12 × 35–50 μm. Capsules ± globose with short straight apiculus, stomata scattered over whole surface of capsule; spores coarsely papillose, 60–80 μm long; calyptrae mitriform. Capsules common, autumn, winter. On acidic or neutral soil on woodland rides, edges of reservoirs. Lowland. Rare or very rare, from Cornwall east to W. Kent and north to Yorkshire and S. Northumberland, Wexford,

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18 Ephemeraceae

W. Galway, Donegal, Antrim. 19, H4. GB16 + 9∗ , IR4. European Southern-temperate. Europe north to S. Sweden and Finland, Israel, Turkey, Morocco. 3 E. cohaerens (Hedw.) Hampe, Flora, 1837 (Fig. 123) Pseudodioicous. Minute ephemeral scattered plants or small patches on persistent protonemata. Leaves patent or recurved, upper and perichaetial leaves lanceolate, acuminate; margins dentate; costa strong above, ending below apex in upper leaves; cells in mid-leaf 10–20 × 50–80 μm. Capsules globose, apiculus short, straight, stomata scattered over whole surface; spores coarsely papillose, 60–70 μm long; calyptrae campanulate, lobed or torn at base. Capsules common, autumn. n = 27. On non-calcareous soil on moist banks and at edges of reservoirs. Lowland. Very rare, W. Sussex, Hertford, Leicester, S. E. Galway (old record), Leitrim. 3, H2. GB3, IR1 + 1∗ . European Temperate. Rare in Europe, extending north to Germany and Poland, Turkey, China, western N. America. This is a critically endangered species in the Red List of British mosses.

4 E. spinulosum Bruch & Schimp. ex Schimp., Syn. Musc. Eur., 1860 (Fig. 124) Pseudodioicous. Minute ephemeral scattered plants, to 2.2 mm high, arising from extensive persistent protonemata. Lower leaves few, patent lanceolate, and perichaetial leaves erect or slightly incurved, linear-lanceolate to linear, acuminate; margins plane, sharply toothed ± from base to apex, teeth spreading or recurved; costa wide, ill-defined, extending to apex, papillose on abaxial side above; mid-leaf cells 11–20 × 40–70 μm, upper cells prorate with spinose papillae. Setae absent; capsules ovoid with oblique blunt apiculus; stomata limited to lower part of capsule; spores 50–70 × 70–110 μm; calyptrae cucullate, ± covering capsules. Capsules common, probably late summer to autumn. On silty mud of a reservoir. Very rare, Antrim. H1. IR1. China, Taiwan, Japan, eastern N. America. Distinguished from other costate species of Ephemerum by the poorly defined costa and all other species occurring in the British Isles by the cells in the upper part of the leaf prorate with spinose papillae. For the occurrence of this plant in Ireland see D. T. Holyoak, J. Bryol. 23, 139–41, 2001. It is possible that it is of casual occurrence having been brought by birds from eastern N. America.

5 E. stellatum H. Philib., Rev. Bryol., 1879 (Fig. 123) Pseudodioicous. Minute ephemeral scattered plants on persistent protonemata. Lower leaves crowded, spreading in stellate fashion, narrowly lanceolate, upper and perichaetial leaves erect-patent, ± straight, ligulate-lanceolate, acute to acuminate; margins entire to slightly denticulate; costa absent; cells thin-walled, in mid-leaf 10–16 × 50–90 μm, incrassate, basal cells larger and shorter, thin-walled. Capsules obovoid with conical apiculus: spores smooth, 40–50 μm; calyptrae large, campanulate, lobed at base covering more than half the capsule. On compressed soil on woodland rides and cliff paths. Lowland. Very rare, Hampshire, W. Sussex,

75 Ephemerum

395

Fig. 124 1–4, Ephemerum serratum var. serratum: 1, leaf (×40); 2, marginal cells from upper part of leaf (×280): 3, capsule (×20); 4, spore (×420). 5, E. serratum var. praecox: leaf (×40). 6–9, E. minutissimum: 6, plant (×30); 7, leaf (×40); 8, marginal cells from upper part of leaf (×280); 9, spore (×420). 10–13, E. spinulosum: 10, plant (×40); 11, leaf (×75); 12, marginal cells from middle of leaf (×420); 13, cells from upper part of leaf, abaxial side (×420).

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18 Ephemeraceae

S. Kerry, old records from E. Sussex and W. Kent. 5, H1. GB2 + 2∗ , IR2. European Temperate. Extremely rare, France, Germany, Portugal, Turkey, N. Africa. This species is considered endangered in the Red List of British mosses and is listed as vulnerable in the Red Data Book of European Bryophytes.

6 E. serratum (Hedw.) Hampe, Flora, 1837 Pseudodioicous. Minute ephemeral scattered or gregarious plants, 1.4–2.2 mm high, on persistent protonemata. Upper and perichaetial leaves erect-patent, lanceolate, apex often twisted; margins spinosely toothed above, teeth straight; costa lacking or very rarely faintly present in upper part of leaf; mid-leaf cells (10−)16–30 × 100–160 μm. Capsules spherical, with conical apiculus, stomata at base of capsule only; spores coarsely papillose, mostly 65–90 μm long; calyptrae small, campanulate, torn at base. Capsules common, autumn to spring. Leaves without costa, cells 16–24 μm wide in upper part of leaf Leaves with faint costa in upper part, cells 10–16 μm wide

var. serratum var. praecox

Var. serratum (Fig. 124) Costa lacking; cells in upper part of leaves 16–24 μm wide. On damp noncalcareous soil in fields, grassland, on roadsides and margins of lakes and reservoirs. 0–350 m. Occasional in lowland England, rare in Scotland, extending north to Shetland, rare in Ireland. 52, H9. European Temperate. Europe north to Fennoscandia, China, Morocco, N. America. Var. praecox A. W. H. Walther & Molendo, Laubm. Oberfrank., 1868 E. intermedium Braithw.

(Fig. 124)

Faint costa present in upper part of leaves; cells in upper part of leaf 10–16 μm wide. Very rare and not seen recently, several localities in W. Sussex. 1. Bavaria. Whether var. praecox is worth maintaining as a variety is very questionable.

7 E. minutissimum Lindb., Not. Sllsk. Fauna Fl. Fenn. F¨ohr., 1874 (Fig. 124) E. serratum var. angustifolium auct. non Bruch & Schimp., E. serratum var. minutissimum (Lindb.) Grout Pseudodioicous. Minute ephemeral scattered or gregarious plants, 1.0–1.8 mm high, on persistent protonemata. Upper and perichaetial leaves narrowly lanceolate; margins spinosely toothed above, teeth often recurved; costa lacking; cells in mid-leaf c. 20 μm wide. Capsules spherical, with conical apiculus; stomata at base of capsule only; spores finely papillose, 50–65 μm long, often surrounded by hyaline membrane; calyptrae small, campanulate, torn at base. On damp noncalcareous soil in fields, grassland and on woodland rides. Lowland. Frequent

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397

in lowland Britain becoming rarer northwards, extending north to Shetland. 85, H17. European Temperate. Europe, extending north to southern Scandinavia, Israel, N. America. The treatment of E. minutissimum varies from synonymy with E. serratum to specific status. On the basis of examination of European material, S. Risse (Bryological Times 90, 6, 1995 and 92, 7, 1997) considers the two taxa to be specifically distinct and I have followed him. The nature of the spores is the only reliable character and it is necessary that mature capsules are examined. E. minutissimum is the more frequent of the two, especially in arable fields, but it does not occur beside lakes or reservoirs.

10 Grimmiales Acrocarpous or cladocarpous. Tufted or cushion- or mat-forming plants. Leaves ovate to linear, often with hyaline apices; upper cells small, quadrate, rounded or rectangular, incrassate, sinuose or esinuose, 1–3-stratose, papillose or not, lower cells longer, less incrassate, walls sometimes strongly sinuose or sinuose-nodulose, sometimes hyaline. Setae short or long, straight or variously curved; capsules spherical to cylindrical, smooth or striate; peristome usually present, single, teeth papillose, entire or variously perforated or cleft; calyptrae cucullate or mitriform. Nearly all the species are saxicolous. Four families.

19 Grimmiaceae Acrocarpous or cladocarpous. Leaves erect and appressed to tightly incurved, rarely crisped when dry, often with hyaline apices; margins usually entire; costa ending below apex to excurrent, if apex hyaline then costa ending below or in hyaline part; basal cells quadrate to ± linear, thin-walled to strongly incrassate, esinuose, sinuose or sinuose-nodulose, alar cells usually undifferentiated, upper cells quadrate to rectangular, 1–3-stratose, smooth or papillose. Capsules immersed, emergent or exserted. Eight genera. The differences between the first three genera or the Grimmiaceae are very trivial and some authorities (e.g. Crum & Anderson, 1981) recognise only a single genus, Grimmia. S. P. Churchill (in V. A. Funk & D. R. Brooks, eds., Advances in Cladistics, pp. 127–44, 1981), on the basis of a cladistic analysis, places Campylostelium, Ptychomitrium and Racomitrium in the subfamily Ptychomitrioideae of the Grimmiaceae. I find this treatment unacceptable on morphological and anatomical grounds as the first two genera differ from members of the Grimmiaceae as usually defined and are much better placed in a separate family.

76 COSCINODON SPRENG., ANLEIT. KENTN. GEW., 1804 Acrocarpous. Leaves lanceolate, plicate or not above; margins plane; hyaline points usually present; basal cells rectangular, hyaline, cells above shorter. Setae straight; capsules erect, emergent; peristome teeth cribrose; columella not falling with lid;

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19 Grimmiaceae

Fig. 125 Coscinodon cribrosus: 1, leaves (×15); 2, mid-leaf cells (×420); 3, basal marginal cells (×420); 4, leaf sections (×210); 5, peristome tooth (×115); 6, capsule (×22.5); 7, calyptra (×22.5).

calyptrae campanulate, plicate, enveloping capsule. A small genus of 7 species occurring in the Northern Hemisphere, S. America and New Zealand. Derivation: from sieve and tooth, referring to the cribrose peristome teeth.

1 C. cribrosus (Hedw.) Spruce, Ann. Mag. Nat. Hist., 1849 Grimmia cribrosa Hedw.

(Fig. 125)

Dioicous. Dense blackish or greyish, often dust-filled cushions, tufts or patches, hoary when dry, to 1 cm high. Leaves appressed when dry, erect-patent when moist, ovate to lanceolate, apex broad, upper leaves longitudinally plicate near costa above; margins plane, entire; hyaline points of upper leaves 1 /4 –1(−2) length of lamina, flattened at base and sometimes decurrent down margins, terete above, smooth or occasionally slightly denticulate; basal cells rectangular, thin-walled, ± hyaline, towards margins shorter with thickened transverse walls, cells above quadrate, not sinuose, often partially bistratose, 8–10 μm wide in mid-leaf, cells of plicae with more heavily thickened walls. Perichaetial leaves larger and wider than vegetative. Setae short, straight; capsules emergent, erect, obloid; peristome teeth strongly cribrose, fragile; spores 10–12(−14) μm, calyptrae plicate, campanulate, partially covering capsules. Capsules occasional, spring.

77 Schistidium

399

Crevices and cracks of very acidic, especially slatey rocks, more rarely on rock faces. 0–500 m. Occasional in N. Wales and N. W. England, very rare elsewhere, E. Cornwall, S. Devon, Carmarthen, Cardigan, N. E. and Mid-West Yorkshire, Dumfries, Kirkcudbright, Midlothian, Mid Perth. 18. GB26 + 11∗ . Circumpolar Boreo-temperate. Rare in Europe from Sicily and Sardinia north to c. 69◦ N, Cyprus, Turkey, Caucasus, Siberia, Himalayas, Japan, Tenerife, N. Africa, N. America, Greenland, Patagonia. C. cribrosus may be mistaken for a Schistidium or Grimmia species, especially when sterile. It differs from both in the leaves plicate above, the campanulate plicate calyptrae and the strongly cribrose peristome teeth. It also differs from Schistidium species (except S. trichodon) in the columella not falling with the lid.

77 SCHISTIDIUM BRID., MUSCOL. RECENT SUPPL., 1819 Autoicous or rarely dioicous. Acrocarpous plants forming cushions, tufts or rough mats. Leaves narrowly lanceolate to ovate; margins plane or recurved; with or without hyaline points; costa ending below apex to excurrent; basal cells quadrate to rectangular, incrassate, not hyaline, cells towards margins shorter, sometimes hyaline, cells above quadrate to shortly rectangular, incrassate, sinuose or not, papillose or not, 1–2-stratose, 1–3(−4)-stratose at margins. Perichaetial leaves much longer than and often differing in shape from vegetative leaves, sheathing and hyaline at base, usually overtopping and sometimes concealing capsules. Setae short, straight; capsules immersed, erect, annulus absent; columella attached to and falling with lid (except in S. trichodon); peristome teeth entire, cleft or variously perforated; calyptrae small, cucullate or mitriform, not plicate. About 120– 150 species world-wide with c. 50 in Europe, occurring particularly on nutrientrich rocks in arctic to temperate regions but occurring in warmer parts at higher altitudes. Derivation: from the Greek word for split, presumably referring to the split calyptra. B. Bremer published a taxonomic revision of Schistidium (Lindbergia 6, 1–6, 89–117, 1980, 7, 73–90, 1981), but her treatment of the S. apocarpum agg. is very unsatisfactory and does not reflect the true situation. The Schistidium apocarpum complex in Scandinavia has recently been revised by H. H. Blom (1996) and he describes 31 Scandinavian species. He gives a briefer account of the genus in Nyholm (1998). Blom reports 11 species, one subspecies and a variety from the British Isles compared with the five species and two varieties previously recognised. I have followed Blom’s (in Nyholm 1998) subdivision of the genus.

Notes on the identification of Schistidium species Care should be taken that vegetative and perichaetial leaves are not confused as the two usually differ markedly in shape and areolation. Leaf descriptions are of upper leaves; lower leaves may have shorter hyaline points or be epilose and, in the case of species with papillose cells, the papillae may have been lost. Papillae are best seen on leaves at the shoot apex. Several leaves should be examined

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especially for the detection of marginal teeth. The relative degree of thickening of the longitudinal and transverse walls of the basal marginal cells of the leaves is a very useful character, especially when taken in conjunction with the shape of the exothecial cells in the lower half of the capsule. The perichaetial leaves extend beyond the capsules to a varying degree depending upon species; when described as not concealing capsules in side view this means that at least part of a capsule is visible. Capsule shape is of moist capsules that have not been placed under a cover-slip – doing so will flatten capsules and considerably alter their shape. Capsule shape and dimensions exclude the capsule lid. Careful comparison should be made with descriptions as it is possible that species may be found additional to those reported from the British Isles. It should also be borne in mind that mixed populations occur, which may cause confusion. Records in Blockeel & Long (1998) for S. apocarpum and S. confertum cannot be accepted as many gatherings named as these belong to other species of the complex. There are inadequate records of S. papillosum, S. frigidum, S. crassipilum and S. elegantulum which give no more than an indication of frequency and distribution. There is no reason to doubt records of S. trichodon, S. strictum, S. robustum and S. atrofuscum as the great majority of specimens I have seen have been correctly determined. 1 Leaves without hyaline points, capsules ± hemispherical or turbinate after dehiscence, spores 16–28 μm 2 Hyaline points usually but not always present and sometimes very short, capsules hemispherical to shortly cylindrical after dehiscence, spores usually 8–15 μm 5 2 Leaves rigid when moist, costa percurrent to excurrent, spores 20–28 μm, plants of acidic rocks near the sea 1. S. maritimum Leaves soft when moist, costa ending in or below apex, spores 16–20 μm, plants on rocks in or by fresh water 3 3 Capsules obloid after dehiscence, turbinate when dry and empty, leaves oblong-ligulate to linear-lanceolate, margins usually plane 4. S. agassizii Capsules ± hemispherical after dehiscence, leaves lanceolate to broadly ovate, margins recurved 4 4 Leaves lanceolate to ovate-lanceolate, often asymmetrical and secund, costa 65–145 μm wide near base, perichaetial leaves overtopping capsules, exothecial cells incrassate 2. S. rivulare Leaves ovate-lanceolate to ovate, symmetrical, straight, costa 48–90 (−105) μm wide near base, perichaetial leaves not or scarcely overtopping capsules, exothecial cells thin-walled 3. S. platyphyllum 5 Mid-leaf cells 8–12 μm wide 6 Mid-leaf cells mostly 5–8 μm wide 17 6 Leaf margins toothed (sometimes bluntly and obscurely so), papillose-denticulate or papillose towards apex 7 Leaf margins entire towards apex 11

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7 Basal marginal cells of leaves sometimes hyaline, transverse walls more strongly thickened than longitudinal walls, exothecial cells in middle and lower half of capsule mostly shortly rectangular, spores mostly c. 10 μm 16. S. crassipilum Basal marginal cells not hyaline, walls of ± uniform thickness, exothecial cells in middle and lower half of capsules mostly ± isodiametric or wider than long, spores 10–15(−19) μm 8 8 Plants dull green to brownish or black, at least some leaf margins bluntly toothed towards apex, cells smooth 9 Plants usually reddish or rust coloured, margins papillose or papillose-denticulate towards apex, cells sparsely to densely papillose in upper part of leaf 10 9 Plants dull green to brownish, columella falling with lid, peristome teeth patent to spreading when dry 5. S. apocarpum Plants blackish, columella persisting, peristome teeth incurved with overlapping tips when dry 6. S. trichodon 10 Leaf cells strongly papillose on abaxial side, papillae on abaxial side of costa tall (to 10 μm high) in upper part of leaf, capsules 1.5–2.0 times as long as wide 7. S. papillosum Leaf cells sparsely papillose on abaxial side, papillae on abaxial side of costa low (to 5 μm high) in upper part of leaf, capsules 1.1–1.4 times as long as wide 9. S. strictum 11 Basal marginal cells of leaves with walls of ± uniform thickness 12 Basal marginal cells of leaves with transverse walls more strongly thickened than longitudinal walls 14 12 Plants often somewhat hoary when dry, hyaline points coarse, 0.4–1.6 mm long, mid-leaf cells shortly rectangular, walls strongly sinuose, exothecial cells mostly shortly rectangular 11. S. robustum Plants rarely hoary, hyaline points slender, mostly 0–0.5 mm long, mid-leaf cells ± quadrate, esinuose to sinuose, exothecial cells ± isodiametric to wider than long 13 13 Perichaetial leaves broad, ligulate-lanceolate to ovate or elliptical, ± concealing capsules in side view, hyaline points mostly 0–0.5 mm long, as wide at base as green lamina apex 5. S. apocarpum Perichaetial leaves long and narrow, ligulate-lanceolate, hyaline points 0–150 μm long, narrower at base than green lamina apex 10. S. dupretii 14 Plants black, forming readily disintegrating tufts, leaves brown, opaque above 15. S. atrofuscum Plants not as above 15 15 Basal marginal cells hyaline with very strongly thickened transverse walls, forming a border, mid-leaf cells 6–10 μm wide, exothecial cells variable in shape in middle and lower half of capsules 14. S. frigidum Basal marginal cells forming a border or not, mid-leaf cells 8–10(−12) μm wide, exothecial cells shortly rectangular 16

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16 Plants rarely hoary when dry, leaves ovate to lanceolate, acute, hyaline points flattened below, usually decurrent down margins 16. S. crassipilum Plants often somewhat hoary when dry, leaves lanceolate or narrowly lanceolate, acuminate, hyaline points not flattened below, not decurrent down margins 17. S. elegantulum 17 Upper cells of leaves papillose, margins and abaxial side of costa papillose above, basal marginal cells not hyaline, with walls of ± uniform thickness 8. S. pruinosum Leaf margins entire, cells and costa smooth, basal marginal cells hyaline, transverse walls more strongly thickened than longitudinal walls 18 18 Perichaetial leaves plicate, capsules apparently gymnostomous, with conspicuously red mouths 13. S. flaccidum Perichaetial leaves not plicate, capsules with peristomes, mouths dull deep red 19 19 Basal cells of leaves 20–40 μm long, basal marginal cells quadrate or shortly rectangular, nor forming a border, cells above not or hardly sinuose, exothecial cells in middle and lower half of capsules shortly rectangular 12. S. confertum Basal cells 40–75 μm long, basal marginal cells hyaline, rectangular, forming a border, cells above usually sinuose, exothecial cells in middle and lower half of capsules irregular in shape 14. S. frigidum

Apocarpum group Leaf margins plane or recurved, sometimes papillose or toothed above; hyaline points when present thin, flexuose; costa sometimes papillose on abaxial side above; marginal basal cells chlorophyllous, walls ± uniformly thickened, cells in upper part of leaf ± isodiametric, mostly unistratose except at margins, smooth or papillose. Exothecial cells shortly rectangular, ± isodiametric or wider than long; peristome teeth strongly curved when dry. Rivulare subgroup Leaves with very short or no hyaline point; cells ± quadrate, slightly sinuose. Capsules subglobose or ovate-obloid when mature, hemispherical or turbinate when dry and empty; exothecial cells thin- or thick-walled; peristome teeth long, curved; spores 16–28 μm. KOH laminal reaction orange or red. Five species in N. W. Europe. Although Blom (in Nyholm, 1998) treats the Rivulare subgroup as a group distinct from the Apocarpum group, more recently he has combined the two groups (pers. commun.).

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1 S. maritimum (Turner) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1845 (Fig. 126) Grimmia maritima Turner Dark green to dark brown tufts or cushions, to c. 2 cm high. Leaves rigid, erect, appressed, curved when dry, erect-patent when moist, ovate to lanceolate, tapering to blunt apex; margins recurved below on one or both sides; hyaline points lacking; costa strong, sometimes thickened above, percurrent to excurrent in stout point; basal cells rectangular, pellucid, shorter towards margins, cells above quadrate, incrassate, slightly sinuose, slightly papillose, opaque, bistratose at margins and towards apex, 8–10 μm wide in mid-leaf. Perichaetial leaves larger than vegetative leaves, from ± narrowly rectangular basal part narrowed to bluntly pointed acumen; costa excurrent. Capsules immersed, ovate-obloid at maturity, turbinate when dry and empty; exothecial cells mostly rectangular but irregularly arranged, walls somewhat thickened; peristome teeth red, reflexed when dry, perforated; spores 20–26(−28) μm. Capsules common, winter. n = 13∗ . Crevices and ledges of acidic coastal rocks and cliffs within the sea-spray zone, very rare on basic rocks. Lowland. Frequent or common and sometimes locally abundant on rocky shores along the west coast of Britain from Cornwall and Devon north to Shetland, rarer along the east coast, from N. E. Yorkshire northwards, common along the west coast of Ireland, rare elsewhere. 51, H21, C. GB288 + 84∗ , IR56 + 19∗ , C6. Oceanic Boreo-temperate. Atlantic and Baltic coasts of Europe north to Svalbard, Faeroes, Iceland, Jan Mayen, Japan, N. American coasts, Greenland, southern S. America. Usually only found in the spray zone and not more than 400 m from the sea except on some of the western Scottish Islands or as a relic in silted or reclaimed estuaries. Spore dispersal seems very inefficient as capsules produced in the previous year may still remain about 3 /4 full of spores. British and Irish material belongs to ssp. maritimum; ssp. piliferum (I. Hagen) Bremer, in which the leaves have a spinulose hyaline point, occurs in Scandinavia, N. America and Greenland.

2 S. rivulare (Brid.) Podp., Beih. Bot. Centralbl., 1911 (Fig. 127) G. alpicola var. rivularis (Brid.) Wahlenb., S. alpicola var. rivulare (Brid.) Limpr. Dark green cushions or prostrate or floating tufts, 2.5–10.0 cm long; stems much branched, often denuded below. Leaves ± secund, often asymmetrical, sharply keeled, lanceolate to ovate-lanceolate, (1.5−)2.0–3.2(−3.4) times as long as wide, acute to obtuse; margins recurved, usually more on one side than the other, entire or bluntly toothed near apex; hyaline points lacking; costa ending in or below apex, often curved, 65–145 μm wide near base; basal cells rectangular, basal marginal cells rectangular, walls of uniform thickness, cells above thinwalled to incrassate, quadrate, not or slightly sinuose, bistratose at margins and towards apex, 8–10 μm wide in mid-leaf. Perichaetial leaves longly overtopping

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Fig. 126 1–7, Schistidium maritimum: 1, shoot with sporophyte; 2, leaves; 3, mid-leaf cells (×420); 4, perichaetial leaf; 5, dry empty capsule; 6, exothecial cells (×210). 7, peristome tooth. 8–14, S. agassizii: 8, shoot with sporophyte; 9, leaves; 10, mid-leaf cells (×420); 11, perichaetial leaf; 12, dry empty capsule; 13, exothecial cells (×210). 14, peristome tooth. Shoots ×12, leaves and capsules ×20, teeth ×60.

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Fig. 127 1–7, Schistidium platyphyllum: 1, shoot with sporophyte; 2, leaves; 3, mid-leaf cells (×420); 4, perichaetial leaf; 5, dry empty capsule; 6, exothecial cells (×210); 7, peristome tooth. 8–14, S. rivulare: 8, shoot with sporophyte; 9, leaves; 10, mid-leaf cells (×420); 11, perichaetial leaf; 12, dry empty capsule; 13, exothecial cells (×210); 14, peristome tooth. Shoots ×12, leaves and capsules ×20, teeth ×60.

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capsules. Surface cells of setae incrassate, walls to 4.5 μm thick; capsules subglobose before dehiscence, hemispherical when empty; exothecial cells ± isodiametric, incrassate; peristome teeth bright red, recurved when dry, with few to many perforations; spores 16–20 μm. Capsules common, autumn to spring. n = 13∗ . On rocks, tree boles and roots by base-rich or base-poor rivers and lakes; when by rivers with fluctuating water levels usually occupying middle part of flood-zone. 0–760 m. Absent from most of lowland England, frequent or common elsewhere. 73, H17. GB386 + 69∗ , IR319. Europe north to Svalbard, Faeroes, Iceland, N. and E. Asia, N. America, Greenland, southern S. America, Australasia, Antarctica. The descriptions of this and the next species have been modified in the light of observations by A. Orange (Bull. Br. Bryol. Soc. 65, 51–8, 1995). The main characters separating the two species are leaf shape and costa form; perichaetial leaf length is also a useful character. Forms of S. apocarpum in riparian habitats may have very short or no hyaline points to the leaves but the plants are usually yellowish-brown, the leaf cells are usually sinuose and the capsules ovate-obloid. S. agassizii differs in capsule and leaf shape and leaf cells unistratose throughout. There are no intermediates between this and the next taxon (A. Orange, loc. cit.), and there seems good reason for treating them as distinct species.

3 S. platyphyllum (Mitt.) H. Perss. in H. Perss. & Gjaever., Kongel. Norske Vidensk. Selsk. Forh., 1961 (Fig. 127) ¨ Grimmia apocarpa var. alpicola auct. non (Hedw.) Rohl., S. alpicola auct. non (Hedw.) Limpr., S. latifolium (J. E. Zetterst.) Weim., S. rivulare ssp. latifolium (J. E. Zetterst.) B. Bremer Dark green tufts or cushions, 0.5–4.0 cm high; stems sparsely branched. Leaves not or slightly secund, symmetrical, widely keeled, broadly ovate to ovate-lanceolate, 1.5–2.7(−2.8) times as long as wide, acute to subobtuse; margins recurved, usually equally on both sides, entire or bluntly toothed above; hyaline points lacking; costa ending in or below apex, straight, 48–90(−105) μm wide near base; basal cells rectangular, basal marginal cells rectangular, walls of ± uniform thickness, cells above quadrate, thin-walled to slightly incrassate, not or hardly sinuose, bistratose at margins and towards apex, 8–10 μm wide in mid-leaf. Perichaetial leaves of ± similar size to upper vegetative leaves, lingulate to broadly lingulate, shortly pointed, not or scarcely overtopping capsules but when doing so concealing capsules in side view. Capsules subglobose, hemispherical when empty, exothecial cells thin-walled; peristome teeth bright red, recurved when dry, with numerous perforations; spores 16–20 μm. Capsules common, spring. On rocks beside rivers with base-rich water, especially in limestone areas. Occasional in S. Wales and N. England, very rare elsewhere, Dumfries, Berwick, W. Lothian, Mid and E. Perth, Skye, Shetland, rare in Ireland. 32, H7. GB24 + 14∗ , IR5 + 2∗ . Circumpolar

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Boreo-temperate. Europe north to Svalbard, Siberia, Kashmir, Japan, Azores, N. and C. Africa, N. and C. America, Greenland, Peru. H. H. Blom (in Nyholm, 1998) reports hyaline points in S. platyphyllum 0–0.3 mm long, but I have not seen hyaline points in British plants. British and Irish material belongs to ssp. platyphyllum; ssp. abrupticostatum (Bryhn) Blom. occurs in arctic regions.

4 S. agassizii Sull. & Lesq. in Sull., Musci Bor.-Amer., 1856 Grimmia agassizii (Sull. & Lesq.) A. Jaeger

(Fig. 126)

Small brownish cushions to lax tufts, 1.5–5.0 cm high. Leaves oblong-ligulate to linear-lanceolate, subacute, obtuse or rounded; margins plane or rarely narrowly recurved below, entire or crenulate above; hyaline points lacking; costa ending below apex; basal cells rectangular, shorter towards margins, cells above quadrate, ± sinuose, unistratose throughout, 8–10 μm wide in mid-leaf. Perichaetial leaves overtopping but not concealing capsules in side view. Capsules obloid, turbinate when empty; exothecial cells incrassate, mostly wider than long; peristome teeth red, strongly recurved when dry, narrowly perforated; spores 16–20 μm. Capsules occasional, spring. On basic rocks subject to flooding by fastflowing streams and rivers, on boulders in hollows subject to seasonal flooding. 300–1100 m. Rare, in scattered localities in N. W. Wales and N. England north to E. Ross and Sutherland. 13. GB8 + 5∗ . European Boreal-montane. Europe north to Svalbard, Iceland, N. America, Greenland. Showing considerable variation in leaf shape, with plants growing submerged in fastflowing water tending to have narrower more acute leaves than plants less subject to submergence. Misidentified in the past as S. rivulare, this species is less rare in Britain than originally thought. For accounts of S. agassizii in Britain see H. H. Birks & H. J. B. Birks, Trans. Br. Bryol. Soc. 5, 215–17, 1967, N. T. H. Holmes, J. Bryol. 9, 275–8, 1976 and A. Orange, Bull. Br. Bryol. Soc. 65, 51–8, 1995. The correct name of this plant is currently uncertain as the type specimen is what has for a long time been known as S. alpicola (i.e. S. platyphyllum). Clearly, confusion would arise if the name of S. agassizii were to be changed to S. alpicola, but the matter has not yet been decided upon.

Species 5–17, Schistidium apocarpum complex In his monograph of the Schistidium apocarpum complex, Blom (1996) recognised 31 species and an additional two species appear on his account in Nyholm (1998) of which 13 are reported from the British Isles. Undoubtedly, further species will be added to these in due course. For an excellent account of and key to all the N. W. European species see H. H. Blom in Nyholm (1998). The following descriptions are based upon British specimens supplemented from Blom (in Nyholm, 1998) where material has not been adequate.

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Apocarpum subgroup Leaf margins often bluntly toothed above; hyaline points thin; costa often papillose on abaxial side above; cells smooth. Capsules cup-shaped to shortly cylindrical, not narrowed at mouth when dry and empty; peristome teeth often semi-perforated in middle and lower part. KOH laminal reaction orange or red. Six species in N. W. Europe. 5 S. apocarpum (Hedw.) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1845 (Fig. 128) Grimmia apocarpa Hedw. Dull green to brownish tufts, patches or rough mats, shoots procumbent to suberect, 0.5–5.0(−8.0) cm long. Epidermal cells of stems strongly incrassate with small lumens. Leaves appressed, sometimes subsecund when dry, erect-patent, sometimes subsecund when moist, straight to subfalcate, ovate to narrowly lanceolate, sharply keeled above; margins recurved ± from base to apex, entire or sparsely bluntly toothed towards apex; hyaline points usually present, (0−)0.05– 0.50(−1.20) mm long, thin, flexuose, entire to spinulose-denticulate, decurrent down margins or not; costa smooth or with sparse low papillae on abaxial side above; basal cells rectangular, thin-walled to incrassate, chlorophyllous, basal marginal cells shortly rectangular to wider than long, not larger than cells above, walls of ± uniform thickness, cells above rounded-quadrate to shortly rectangular, incrassate, usually sinuose, smooth, ± unistratose, in mid-leaf mostly 8–10 μm wide, margins 2–3(−4)-stratose. Perichaetial leaves larger than vegetative leaves, lingulate-lanceolate to ovate, concealing capsules in side view. Capsules orange to orange-red, obloid, 1.2–1.6(−2.0) times as long as wide; exothecial cells thinwalled, ± isodiametric to wider than long in middle and lower half of capsule; peristome teeth red, patent to spreading, curved and twisted, with upturned tips when dry, (350−)400–700 μm long, longly tapering, perforated or not, coarsely papillose above; spores 11–15(−19) μm. Capsules common, winter, spring. On exposed basic rocks, walls, mortar, concrete, in a wide range of habitats, very rarely on trees. 0–1210 m (summit of Ben Lawers). Occasional to frequent in lowland England, frequent or common elsewhere. Eurasian Boreo-temperate. Europe north to western Norway, Faeroes, Caucasus, Altai, Siberia, Madeira, Newfoundland. Forms of this plant with costae papillose on the abaxial side above may be mistaken for S. papillosum, S. pruinosum or S. strictum, but these species have leaf margins papillose or papillose-denticulate above and the costae more densely papillose; the first two have strongly papillose lamina cells and the last has shorter capsules. Most likely to be confused with S. crassipilum or S. elegantulum (q.v.).

6 S. trichodon (Brid.) Poelt, Svensk. Bot. Tidskr, 1953 Grimmia trichodon Brid.

(Fig. 128)

Plants forming black tufts or straggling, sometimes extensive patches, shoots greenish only at the tips, leafless below, to 8 cm long. Leaves straight to subsecund

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Fig. 128 1–7, Schistidium apocarpum: 1, shoot with sporophyte; 2, leaves; 3, leaf apex in side view (×60); 4, basal marginal cells (×420); 5, mid-leaf cells (×420); 6, perichaetial leaf; 7, dry empty capsule; 8, exothecial cells (×210); 9, peristome tooth. 10–18: S. trichodon: 10, shoot with sporophyte; 11, leaves; 12, leaf apex in side view (×60); 13, basal marginal cells (×420); 14, mid-leaf cells (×420); 15, perichaetial leaf; 16, dry empty capsule; 17, exothecial cells (×210); 18, peristome tooth. Shoots ×12, leaves and capsules ×20, teeth ×60.

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when dry, erect-patent, sometimes subsecund when moist, ovate-lanceolate, tapering to acuminate apex from widest part; margins narrowly recurved, irregularly bluntly toothed towards apex at least in some leaves; hyaline points 0–80 μm long, spinulose, decurrent down margins; costa often papillose on abaxial side above; basal cells rectangular, chlorophyllous, basal marginal cells quadrate to wider than long, walls ± uniformly thickened, cells above shortly rectangular to rounded-quadrate, incrassate, sinuose, smooth, ± unistratose, in mid-leaf 8–10 μm wide, at margins bistratose but with unistratose patches in middle and upper part of leaf. Perichaetial leaves larger than vegetative leaves, ovatelanceolate, ± concealing capsules in side view; hyaline points 0–100 μm long. Capsules obloid, 1.4–2.1 times as long as wide; exothecial cells ± isodiametric to shortly rectangular in middle and lower half of capsule, thin-walled; peristome teeth red, incurved with tips overlapping when dry, (450−)500–650(−750) μm long, longly tapering, narrowly perforated or not, finely papillose throughout; columella persisting; spores 10–14 μm. Capsules common, winter, spring. Exposed calcareous rocks. 10–1100 m. Caernarfon, occasional in the Pennines and the central Scottish Highlands, very rare further north, extending to W. Sutherland. 15. GB18 + 1∗ . Circumpolar Boreal-montane. Europe from the Alps and Carpathians north to northern Norway, Iceland, Georgia, Armenia, N. W. India, China, Japan, N. America. Whilst the tips of the peristome teeth overlapping when dry is a feature unique to S. trichodon in the genus, the teeth are in a suitable state for only a short time during the year. In the absence of suitable capsules it differs from S. apocarpum in its black colour, the very short or absent hyaline points of the leaves, which are acuminate rather than acute as in S. apocarpum. This plant was first reported from Britain by A. C. Crundwell, Trans. Br. Bryol. Soc. 3, 558–62, 1959. British material belongs to var. trichodon; var. nutans Blom, in which the plants are smaller and brownish with arcuate, secund stems and relatively longer capsules, is known from Scandinavia and could occur in Britain.

Strictum subgroup Plants often reddish. Leaf margins papillose or papillose-denticulate above; hyaline points thin; costa papillose on abaxial side above; cells in upper part of leaf papillose. Exothecial cells ± isodiametric or wider than long. KOH laminal reaction orange or red. Seven species. 7 S. papillosum Culm. in Amann, Fl. Mouss. Suisse, 1918 (Fig. 129) Lax or dense tufts or patches, reddish above, olivaceous below. Shoots to 10 cm long. Epidermal cells of stems strongly incrassate with small lumens. Leaves appressed to subsecund when dry, erect-patent, subsecund when moist, straight to subfalcate, lanceolate to ovate, gradually tapering from widest part to acute to acuminate apex; margins recurved in middle and lower part or ± from base to apex, papillose-denticulate above; hyaline points 0–0.50(−1.25) mm long but often short, thin, flexuose, slightly to strongly spinulose-denticulate at least below,

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Fig. 129 1–9, Schistidium papillosum: 1, shoot with sporophyte; 2, leaves; 3, leaf apex in side view (×60); 4, basal marginal cells (×420); 5, mid-leaf cells (×420); 6, perichaetial leaf; 7, dry empty capsule; 8, peristome tooth; 9, exothecial cells (×210). 10–18: S. pruinosum: 10, shoot with sporophyte; 11, leaves; 12, leaf apex in side view (×60); 13, basal marginal cells (×420); 14, mid-leaf cells (×420); 15, perichaetial leaf; 16, dry empty capsule; 17, exothecial cells (×210); 18, peristome tooth. Shoots ×12, leaves and capsules ×20, teeth ×60.

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shortly to longly decurrent down margins; costa strongly papillose on abaxial side, papillae to 10 μm high; cells incrassate, basal rectangular, not sinuose, chlorophyllous, basal marginal cells quadrate to wider than long, walls of ± uniform thickness, cells above mostly shortly rectangular, sinuose, strongly papillose on abaxial side, sparsely papillose on adaxial side, ± unistratose, 8–10 μm wide in mid-leaf. Perichaetial leaves ± similar in shape to vegetative leaves or linearlanceolate, larger, concealing capsules in side view or not. Capsules dark red to reddish brown, obloid, 1.5–2.0 times as long as wide; exothecial cells quadrate to wider than long in middle and lower half of capsule, thin-walled; peristome teeth reddish, erect-patent, curved and twisted, becoming squarrose with age when dry, (310−)330–500 μm long, tapering to long fine points, entire or with narrow perforations, densely papillose above; spores 10–13 μm. Capsules common, autumn. On basic to acidic sheltered to exposed montane rocks except in the driest habitats. To 1210 m (summit of Ben Lawers). Rare to occasional, Merioneth, Dumfries and the Central Scottish Highlands. Circumpolar Boreo-arctic Montane. Montane and northern Europe north to Svalbard, Faeroes, Iceland, Asia, Madeira, N. America, Greenland. The papillae are best seen on leaves near the stem tips. Much rarer than S. strictum, from which it differs in the leaf cells coarsely papillose and longer capsules.

8 S. pruinosum (Wilson) Roth, Eur. Laubm., 1904 Grimmia conferta var. pruinosa (Wilson) Braithw.

(Fig. 129)

Dense olivaceous or brownish, frequently grit-filled tufts or more rarely patches, often hoary when dry, shoots 1.5–3.0(−4.5) cm long. Leaves appressed when dry, erect-patent when moist, straight, lanceolate to ovate, acute to obtuse, sharply keeled and opaque above; margins recurved on one or both sides, papillose above; hyaline points to 1.6 mm long, terete, straight, entire to spinulose below, decurrent down margins or not; costa papillose above on abaxial side; basal cells rectangular, chlorophyllous, walls moderately thickened, sinuose or not, basal marginal cells quadrate or wider than long, walls of ± uniform thickness, cells above rounded-quadrate, sinuose or not, coarsely papillose on both surfaces, bistratose, opaque in upper part of leaf, 6–8 μm wide in mid-leaf,. Perichaetial leaves ovate-lanceolate, much larger than vegetative leaves, concealing capsules in side view. Capsules red or reddish brown with metallic sheen, obloid, 1.3–2.0 times as long as wide; exothecial cells isodiametric to wider than long in middle and lower half of capsule, thin-walled; peristome teeth red, patent to recurved when dry, straight or curved, 270–390(−450) μm long, narrowly perforated, densely and coarsely papillose above; spores 10–14(−15) μm. Capsules common. On dry or seasonally moist, usually exposed calcareous rocks and cliffs. 400–850 m. Rare, Derby, central Scotland, Clare, Down, Antrim, Londonderry. 11, H4. European Boreal-montane. Northern and montane Europe to 64◦ N, Iceland, Caucasus, Turkey.

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The coarsely papillose cells, 6–8 μm wide in mid-leaf, are diagnostic, distinguishing S. pruinosum from other British and Irish species. Treated by Braithwaite (1887–1905) and Dixon & Jameson (1924) as a variety of S. confertum, despite the opaque strongly papillose leaf cells and longer capsules, and was recognised until the time of the Second World War after which it was treated as a synonym of S. confertum. Thus, a number of records of S. confertum belong to S. pruinosum. Plants of S. pruinosum from dry situations form small hoary cushions, and as the leaves have long hyaline points and are opaque above, they are likely to be mistaken for a Grimmia species with opaque leaf cells, but differ in areolation and the almost always present immersed capsules. Where conditions are moist, the plants form straggling patches and the hyaline points are much shorter. It is such plants that formed the basis of the record of S. boreale Poelt from Scotland (E. F. Warburg, Trans. Br. Bryol. Soc. 4, 757–759, 1965). S. boreale, which is a black plant with papillose leaves, is not known in the British Isles although it could well occur.

˚ 9 S. strictum (Turner) Loeske ex Martensson, Kongl. Svenska Vetensk. Acad. Handl., 1956 (Fig. 130) ¨ ¨ Grimmia apocarpa var. gracilis Rohl., G. stricta Turner, S. gracile (Rohl.) Limpr. Dull red to rust-coloured dense tufts to straggling patches, shoots to 10(−12) cm long. Stems often with dwarf branches; lacking central strand in section. Leaves imbricate when dry, erect-patent when moist, straight or slightly curved, from ovate to lanceolate basal part ± rapidly tapered to acute or acuminate upper part; margins recurved below or sometimes ± to apex, papillose or papillose-denticulate towards apex; hyaline points 0–350(−600) μm long, not or hardly decurrent down margins, sparsely spinulose; costa papillose on abaxial side, papillae to 5 μm high; cells incrassate, esinuose to strongly sinuose, basal rectangular, chlorophyllous, basal marginal cells quadrate to wider than long, walls ± uniformly thickened, cells above rounded-quadrate to shortly rectangular, with scattered low papillae on abaxial side, unistratose with scattered bistratose patches, 8–10 μm wide, in mid-leaf. Perichaetial leaves larger than vegetative leaves, lingulate-lanceolate to ovate, hardly concealing capsules in side view. Capsules deep red, ± spherical to obovoid before dehiscence, 1.1–1.4 times as long as wide; exothecial cells mostly wider than long in middle and lower half of capsule, thin-walled; peristome teeth red, erect-patent when dry, curved and twisted, becoming squarrose with age, 350–500(−570) μm long, entire or with narrow perforations or not, finely papillose, tapering to fine point; spores 12–15(−18) μm. Capsules common, winter. On exposed, dry, basic montane cliff ledges and rocks, rarely in lowland ravines and on sea-cliffs. 0–1210 m. Rare in Wales, N. England and southern Scotland, frequent in parts of the Scottish Highlands, extending north to Orkney, also recorded from S. Devon and Worcester, rare in Ireland. 38, H15. GB103 + 13∗ , IR11 + 8∗ . Suboceanic Wide-boreal. An oceanic species occurring in S. W. Norway, Faeroes, Iceland, Pyrenees, Madeira, western N. America. Most of the specimens I have seen determined as S. strictum are correctly named, very few belonging to S. papillosum or S. apocarpum, so that currently available distribution data are

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Fig. 130 1–9, Schistidium strictum: 1, shoot with sporophyte; 2, leaves; 3, leaf apex in side view (×60); 4, basal marginal cells (×420); 5, mid-leaf cells (×420); 6, perichaetial leaf; 7, dry empty capsule; 8, exothecial cells (×210); 9, peristome tooth. 10–17: S. robustum: 10, shoot with sporophyte; 11, leaves; 12, basal marginal cells (×420); 13, mid-leaf cells (×420); 14, perichaetial leaf; 15, dry empty capsule; 16, exothecial cells (×210); 17, peristome tooth. Shoots ×12, leaves and capsules ×20, teeth ×60.

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likely to be largely accurate. The sparsely papillose leaves and cup-shaped capsules will distinguish S. strictum from S. papillosum and S. pruinosum. The papillae on the leaves are difficult to detect in S. strictum but the usually reddish coloration, the leaf margins papillosedenticulate above and the costae papillose on the abaxial side will identify this plant. Forms of S. apocarpum and S. crassipilum with papillose costae differ in their longer capsules and leaf shape; S. apocarpum does not have papillose-denticulate leaf margins and in S. crassipilum the basal marginal cells of the leaves have the transverse walls strongly thickened. H. H. Blom (in Nyholm, 1998) says that in S. strictum the leaves are spirally arranged when dry, but I find this difficult to detect. He also says it is a lowland species, using this as a key character, but in the British Isles it rarely occurs at low altitudes.

Robustum group Leaf margins recurved, entire; hyaline points coarse or not; basal marginal cells with ± uniformly thickened walls, cells above incrassate, usually longer than wide, smooth. Perichaetial leaves long and narrow. Capsules obloid to shortly cylindrical; exothecial cells shortly rectangular or rectangular with unevenly thickened longitudinal walls; peristome teeth spreading to recurved, ± straight. KOH laminal reaction orange or red. Six species in N. W. Europe. ´ W. A. Weber, Phytologia, 1986 10 S. dupretii (Ther.) (Fig. 131) Small brown or more rarely dull green tufts, to c. 1.5 cm high. Stem epidermal cells slightly thickened, with large lumens. Leaves erect when dry, lower leaves patent, upper erect-patent when moist, narrowly lanceolate to ovate-lanceolate, gradually tapering from widest part to obtuse to acute apex; margins broadly recurved at least on one side, entire; hyaline points very short but rarely absent, 0–150 μm long, narrow, spinulose, base narrower than apex of lamina or grading into lamina apex; costa smooth on abaxial side; cells incrassate, basal rectangular, chlorophyllous, esinuose, basal marginal cells quadrate to wider than long, walls of ± uniform thickness, cells above rounded-quadrate to shortly rectangular, sinuose or not, smooth, unistratose or with bistratose patches, mostly 8–10 μm wide in mid-leaf. Perichaetial leaves narrow, ligulate-lanceolate, longly overtopping but not concealing capsules in side view. Capsules reddish brown, shortly cylindrical, 1.4–2.0 times as long as wide, becoming striate in middle and lower 1 /2 –3 /4 when dry and empty; exothecial cells variable in shape in middle and lower half of capsule, thin-walled; peristome teeth red to reddish brown, not curved or twisted, reflexed when dry, (250−)270–380 μm long, tapering to fine point, not perforated, finely papillose above; spores 8–11 μm. Capsules common. On exposed or partially shaded dry calcareous rocks. Apparently very rare, Midlothian, W. and Mid Perth, Angus. 4. Circumboreal Montane. Montane and northern Europe north to northern Norway, Iceland, Georgia, Kazakstan, India, Japan, N. America. S. dupretii may be recognised by its small size and the long narrow perichaetial leaves longly overtopping but not concealing the capsules, a particularly noticeable feature when the plants are dry. This is also a feature of S. frigidum var. havaasii with which S. dupretii is likely to be confused, but S. frigidum differs in capsule shape, leaves with basal marginal

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Fig. 131 1–8, S. dupretii; 1, shoot with sporophyte; 2, leaves; 3, basal marginal cells (×420); 4, mid-leaf cells (×420); 5, perichaetial leaf; 6, dry empty capsule; 7, exothecial cells (×210); 8, peristome tooth. 9–16, S. confertum: 9, shoot with sporophyte; 10, leaves; 11, basal marginal cells (×420); 12, mid-leaf cells (×420); 13, perichaetial leaf; 14, dry empty capsule; 15, exothecial cells (×210); 16, peristome tooth. Shoots ×12, leaves and capsules ×20, teeth ×60. cells rectangular, hyaline, with strongly thickened transverse walls and mid-leaf cells mostly 6–8 μm wide. The small size may also lead to confusion with S. confertum (q.v.).

11 S. robustum (Nees & Hornsch.) H. H. Blom, Bryophyt. Biblioth., 1996 (Fig. 130) Grimmia apocarpa var. homodictyon (Dixon) Crundw., G. homodictyon Dixon, S. apocarpum var. homodictyon (Dixon) Crundw. & Nyholm Dull green to light brown or rusty red tufts or patches, often hoary when dry; shoots 1–3(−5) μm long. Leaves erect when dry, erect-patent when moist, straight,

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lanceolate to ovate-lanceolate, gradually tapering from widest part to acute apex; margins recurved ± from base to apex, entire; hyaline points coarse, straight, flattened below, terete above, spinulose, (0.2−)0.4–1.6 mm long, decurrent down margins, strongly spinulose; costa prominent, smooth on abaxial side above; cells incrassate, walls whitish, basal rectangular, chlorophyllous, strongly sinuose, basal marginal cells quadrate to wider than long, walls of ± uniform thickness, cells above shortly rectangular, strongly sinuose, smooth, unistratose, occasionally with bistratose streaks, 8–12 μm wide in mid-leaf. Perichaetial leaves ligulatelanceolate, not concealing capsules in side view. Capsules light brown, shortly cylindrical, 1.8–2.3 times as long as wide; exothecial cells mainly shortly rectangular in middle and lower half of capsule, thin-walled; peristome teeth orange-red, not curved or twisted, recurved when dry, 300–400 μm long, longly tapering to thin fragile points, perforated, densely papillose above; spores 8–12 μm. Capsules occasional to frequent, winter, spring. On exposed limestone and basic rocks and cliff ledges. 0–750 m. S. E., Mid-West and N. W. Yorkshire, Westmorland, rare to occasional in Scotland from Mid Perth and Angus north to Skye and W. Sutherland. 15. GB28 + 1∗ . European Boreal-montane. Europe north to northern Norway, Corsica, Caucasus, Canada. S. robustum is readily recognised by the long coarse spinulose hyaline points and thickwalled strongly sinuose leaf cells.

Confertum group Plants small, dull green. Leaf margins plane or recurved at about middle on one or both sides, entire; hyaline points thin, ± flattened; basal marginal cells with transverse walls more strongly thickened than longitudinal walls, cells above smooth, small, 6–9 μm wide. Capsules ± spherical to shortly cylindrical; exothecial cells various; peristome teeth irregular, often strongly perforated. KOH laminal reaction intense yellow. Four species in N. W. Europe. The laminal KOH reaction is a useful additional character for members of this group as in all other groups it is orange-red or red.

12 S. confertum (Funck) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1846 (Fig. 131) Grimmia conferta Funck, S. canariense Wint., S. apocarpum var. confertum ¨ (Funck) H. Moller Small tight often grit-filled, dark green cushions, to 1.5 cm high. Stem epidermal cells slightly incrassate, with large lumens. Leaves erect, appressed when dry, erectpatent when moist, straight, narrowly lanceolate to ovate, gradually tapering from widest part to acute apex, bluntly keeled below, sharply keeled above; margins recurved to 3 /4 way up leaf on one side, less so or plane on the other, entire; hyaline points flattened, spinulose-denticulate, 0–200 μm long, not decurrent down margins; costa prominent on abaxial side, smooth above; basal cells rectangular, esinuose, sometimes hyaline, 20–40 μm long, basal marginal cells ± hyaline, quadrate

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to shortly rectangular, transverse walls more strongly thickened than longitudinal walls, cells above hexagonal to rounded-quadrate, thin-walled to incrassate, not or hardly sinuose, 1–2-stratose, 5–8 μm wide in mid-leaf. Perichaetial leaves larger than vegetative leaves, ovate, not plicate, concealing capsules in side view or not. Capsules yellowish brown to reddish brown, cup-shaped after dehiscence, 1.1– 1.3 times as long as wide; exothecial cells mostly shortly rectangular, walls ± uniformly slightly thickened; peristome teeth orange-red, not curved or twisted, erect to erect-patent, becoming reflexed with age when dry, 230–320 μm long, strongly perforated, coarsely papillose above; spores 8–10(−11) μm. Capsules common, spring, autumn. On exposed basic rocks. 5–700 m (Clogwyn Du’r Arddu). Rare, W. Norfolk, scattered localities in Wales and northern Britain, Antrim, Londonderry. 14, H2. Circumpolar Boreo-temperate. Europe north to southern Scandinavia, Iceland, Turkey, Cyprus, Georgia, Armenia, India, China, N. America, Greenland. About 50% of specimens identified as S. confertum have been misnamed and current distribution data cannot be accepted. S. pruinosum, S. frigidum var. havaasii and S. dupretii are similar in appearance. S. pruinosum differs in the usually much longer hyaline points, coarsely papillose leaf cells and longer capsules; S. frigidum var. havaasii has longer basal leaf cells, the rectangular hyaline basal marginal cells with very strongly thickened transverse walls are also distinctive, the cells above sinuose and the exothecial cells variable in shape. S. dupretii has basal marginal cells with walls of ± uniform thickness, long narrow perichaetial leaves and exothecial cells variable in shape.

13 S. flaccidum (De Not.) Ochyra, Nova Hedwigia, 1989 S. pulvinatum (Hedw.) Brid.

(Fig. 132)

Dense olive-green cushions, blackish below, sometimes hoary, 0.5–1.8 cm high. Leaves erect when moist, narrowly lanceolate to ovate; margins plane or recurved on one or both sides, entire; hyaline points 150–850 μm long, flattened, not or hardly decurrent down margins, denticulate; costa smooth on abaxial side; basal cells rectangular, ± hyaline, sinuose and sometimes nodulose, 34–67 μm long, basal marginal cells quadrate to shortly rectangular, ± hyaline, transverse walls strongly thickened, cells above rounded-quadrate, thick-walled, not or slightly sinuose, unistratose with bistratose patches, 7–9(−10) μm wide in mid-leaf. Perichaetial leaves large, plicate, ± concealing capsules in side view. Capsules yellowish brown to orange-brown, ± spherical to obovoid, 0.9–1.3 times as long as wide, cup-shaped after dehiscence; exothecial cells irregularly shaped in upper part of capsule, irregularly rectangular below, thin-walled; lid mamillate; peristome teeth rudimentary, 17–25 μm long, not or scarcely extending beyond bright red capsule mouth; spores 8–10 μm. Capsules common. On exposed baserich rock faces. Very rare, Caernarfon, 1. GB1. Circumpolar Boreal. Montane Europe from Spain and Greece north to Norway, Iceland, Cyprus, Turkey, Azerbaijan, India, Tenerife, N. America, Antarctica. Likely to be confused with S. confertum or S. frigidum var. havaasii, but differing in the apparently gymnostomous red-mouthed capsules and plicate perichaetial leaves. The mamillate

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Fig. 132 1–8, Schistidium frigidum var. frigidum: 1, shoot with sporophyte; 2, leaves; 3, basal marginal cells (×420); 4, mid-leaf cells (×420); 5, perichaetial leaf; 6, dry empty capsule; 7, exothecial cells (×210); 8, peristome tooth. 9–16, S. frigidum var. havaasii: 9, shoot with sporophyte; 10, leaves; 11, basal marginal cells (×420); 12, mid-leaf cells (×420); 13, perichaetial leaf; 14, dry empty capsule; 15, exothecial cells (×210); 16, peristome tooth. 17–24, S. flaccidum: 17, shoot with sporophyte; 18, leaves; 19, basal marginal cells (×420); 20, mid-leaf cells (×420); 21, perichaetial leaf; 22, dry empty capsule; 23 and 24, exothecial cells from upper and lower parts of capsules (×210). Shoots ×12, leaves and capsules ×20, teeth ×60.

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lid of S. flaccidum is unique in the genus, all other species having rostrate lids. Even very old capsules of other species usually have at least some basal parts of the peristome teeth still present. The leaves of S. flaccidum differ from those of S. confertum in the longer hyaline points and longer basal cells and from those of S. frigidum in the cells not or hardly sinuose. For the occurrence of this plant in Britain see C. C. Townsend, J. Bryol. 19, 815–17, 1997.

14 S. frigidum H. H. Blom, Bryophyt. Biblioth., 1996 Small dense olive-green cushions or sometimes extensive tufts; shoots to 2 cm long. Leaves appressed when dry, spreading from erect basal part when moist, linear-lanceolate to lanceolate, acute to acuminate; margins recurved on one or both sides, entire; hyaline points 0–800 μm long, not decurrent down margins, flattened, spinulose; costa smooth on abaxial side; basal cells rectangular, hyaline, not sinuose, 40–75 μm long, basal marginal cells hyaline, rectangular, with very strongly thickened transverse walls, often forming a distinct marginal band, cells above shortly rectangular to quadrate, incrassate, sinuose, smooth, unistratose with bistratose patches, 6–10 μm wide in mid-leaf. Perichaetial leaves larger than vegetative leaves, lingulate-lanceolate to lanceolate, not plicate, concealing capsules in side view. Capsules orange-brown to reddish brown, cup-shaped to shortly cylindrical; exothecial cells variable in shape in middle and lower half of capsule, thin-walled; peristome teeth orange-red, spreading to reflexed when dry, not curved or twisted, 190–300 μm long, tapering to broad obtuse or truncate points, perforated or cleft, coarsely papillose above; spores 10–13(−17) μm. Capsules common, spring. Capsules 1.4–2.1 mm long excluding lid, 1.2–1.5 times as long as wide, perichaetial leaves narrowly elliptical to lanceolate, concave, costa percurrent or excurrent, stems hardly branched var. frigidum Capsules 0.5–0.6 mm long, 0.9–1.2 times as long as wide, perichaetial leaves lingulate-lanceolate, strongly concave, costa ending below apex, stems much branched var. havaasii Var. frigidum (Fig. 132) Dense sometimes extensive tufts. Shoots to 5 cm long; stems hardly branched. Leaves lanceolate; hyaline points 0–800 μm long. Subperichaetial leaves similar to leaves below. Perichaetial leaves narrowly elliptical to lanceolate, concave, costa percurrent to excurrent. Capsules obloid to shortly cylindrical, 1.4–2.1 mm long, 1.2–1.5 times as long as wide; peristome teeth 230–300 μm long. On exposed usually basic montane rocks and ledges, but also on walls, old buildings and slate, often where periodically moist. Rare, in scattered localities in western and northern Britain from Montgomery north to Inverness and Argyll, Sutherland. Circumpolar Boreal-montane. Circumpolar Wide-temperate. Montane and N. Europe north to Svalbard, Jan Mayen, N. W. Russia, Tenerife, Faeroes, Iceland, N. America, Greenland.

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Var. havaasii H. H. Blom, Bryophyt. Biblioth., 1996 (Fig. 132) Dense cushions, to c. 1.5 cm high. Stems much branched. Leaves narrowly lanceolate to lanceolate; hyaline points terete, ± smooth, 0–200 μm long. Subperichaetial leaves much larger than leaves below. Perichaetial leaves lingulate-lanceolate, very concave, costa ending well below apex. Capsules ± spherical to obloid, 0.5– 0.6 mm long, 0.9–1.2 times as long as wide; peristome teeth 190–250(−290) μm long. On exposed basic rock, boulders and in scree. 700–1000 m (Ben Lawers). Caernarfon, N. W. Yorkshire, Dumfries, Mid Perth. 4. European Boreal-montane. Norway. In S. frigidum the basal marginal cells are rectangular, usually hyaline and with very strongly thickened transverse walls – these walls may sometimes be so strongly thickened as to appear quadrate – and often form a distinct border at the base of the leaves. This border and the irregularly shaped exothecial cells will distinguish S. frigidum var. frigidum from S. crassipilum and S. elegantulum. For the differences between S. frigidum var. havaasii and S. dupretii and S. confertum see under those species.

Atrofuscum group Leaf margins plane to recurved to 3 /4 (−4 /5 ) way up leaf, entire; hyaline points where present coarse, terete in upper part; basal marginal cells with transverse walls more strongly thickened than longitudinal walls or not, cells above ± isodiametric, smooth. Exothecial cells rectangular or isodiametric and rectangular mixed. KOH laminal reaction orange or red. Six species in N. W. Europe. 15 S. atrofuscum (Schimp.) Limpr., Laubm. Deutschl., 1889 Grimmia atrofusca Schimp.

(Fig. 133)

Dense blackish, readily disintegrating, often grit-filled tufts or cushions, 1–3 cm high. Epidermal cells of stem slightly incrassate, with large lumens. Leaves brown, opaque above, appressed when dry, erect-spreading when moist, lanceolate to broadly lanceolate, subacute to obtuse; margins recurved on one or both sides, entire; hyaline points usually absent but occasionally present and up to 60 μm long; costa percurrent, smooth on abaxial side, in section hemispherical; cells at extreme base shortly rectangular, ± thin-walled, not sinuose, basal marginal cells quadrate to wider than long, subhyaline, transverse walls more strongly thickened than longitudinal walls, cells above moderately thickened, not or slightly sinuose, smooth, partially bistratose, 8–10 μm wide in mid-leaf. Perichaetial leaves larger than vegetative leaves, elliptical, concealing capsules in side view, hyaline points absent. Capsules deeply immersed, yellow to orange or light orange-brown, obloid, 1.3–1.7 times as long as wide; exothecial cells variable in shape in middle and lower half of capsule, thin-walled; peristome teeth orange, not curved or twisted, patent to reflexed when dry, to 320 μm long, obtuse or truncate, or rudimentary, coarsely papillose; spores c. 10 μm. Capsules occasional. On dry, strongly calcareous boulders. 550–650 m. Very rare, E. Perth, S. Aberdeen, Banff,

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Fig. 133 1–7, Schistidium atrofuscum: 1, shoot with sporophyte; 2, leave; 3, basal marginal cells (×420); 4, mid-leaf cells (×420); 5, perichaetial leaf; 6, dry empty capsule; 7, exothecial cells (×210); 8–16, S. crassipilum: 8, shoot with sporophyte; 9, leaves; 10, leaf apex (×40); 11, basal marginal cells (×420); 12, mid-leaf cells (×420); 13, perichaetial leaf; 14, dry empty capsule; 15, exothecial cells (×210); 16, peristome tooth. Shoots ×12, leaves and capsules ×20, teeth ×60.

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E. Inverness. 4. GB4. European Boreal-montane. Southern Norway, southern Sweden, Austria, Croatia, Czechoslovakia, Germany, Greece, Iceland, Macedonia, Montenegro, Spain, Turkey, western N. America. Readily recognised by the dense blackish readily disintegrating cushions, the brown leaves and the deeply immersed capsules. S. atrofuscum produces capsules less frequently than most other species and as these are deeply immersed they may appear to be lacking. They may, however, be detected by the presence of projecting perichaetial leaves. For the occurrence of this species in Scotland see E. F. Warburg, Trans. Br. Bryol. 3, 172–3, 1957.

16 S. crassipilum H. H. Blom, Bryophyt. Biblioth., 1996 (Fig. 133) Dark olive-green tufts, rarely hoary when dry; shoots 1–3 cm long. Leaves appressed when dry, erect to patent when moist, straight or slightly curved, lanceolate to ovate, acute; margins recurved to 2 /3 –3 /4 way up leaf, sometimes papillosedenticulate or bluntly toothed above, teeth consisting of projecting cell ends; hyaline points 0–1 mm long, coarse, stiff, spinulose-denticulate, flattened towards base, usually decurrent down margins; costa smooth or with scattered low papillae on abaxial side above; basal cells rectangular, incrassate, often noticeably wider than cells above, basal marginal cells ± quadrate and chlorophyllous or rectangular and hyaline and forming a border, transverse walls more strongly thickened than longitudinal walls, cells above mostly quadrate to wider than long, moderately thickened to incrassate, smooth, not or slightly sinuose, 8–10(−12) μm wide in mid-leaf. Perichaetial leaves larger than vegetative leaves, ovate to lanceolate, ± concealing capsules in side view. Capsules reddish brown or orangebrown, obloid or shortly cylindrical, 1.5–2.0 times as long as wide; exothecial cells shortly rectangular in middle and lower half of capsule, walls slightly thickened; peristome teeth red, ± erect to spreading when dry, not curved or twisted, 300– 450 μm long, gradually tapering to narrow or broad, obtuse or truncate apices, not curved or twisted, not perforated, coarsely papillose above, papillae in rows; spores (6−)9–11(−12) μm. Capsules common. Exposed or sheltered dry baserich rocks, cliff ledges, limestone pavement, walls, buildings. 0–720 m. Common, especially in lowland areas and likely to be found in all vice-counties. Circumpolar Wide-temperate. Europe north to W. Norway, Faeroes, Iceland, Georgia, Ukraine, Turkey, Cyprus, Armenia, N. America. Distinguished from S. elegantulum by the more shortly tapered leaves with margins recurved to 2 /3 –3 /4 way up leaf and often toothed or papillose-denticulate towards the apex and the hyaline points flattened below and usually decurrent down the margins; the basal cells are noticeably larger than the cells above and the basal marginal cells are sometimes rectangular and hyaline. This latter feature may lead to confusion with S. frigidum var. frigidum, but that species differs in the entire margins, non-papillose costae, non-decurrent hyaline apices, narrower perichaetial leaves and exothecial cells variable in shape. Also likely to be mistaken for S. apocarpum, but that species differs in the basal marginal cells with ± uniformly thickened walls, the shorter capsules, exothecial cells ± isodiametric or wider than long in the lower half of the capsule and smaller spores. Where the leaf

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margins are papillose-denticulate and/or the costae sparsely papillose on the abaxial side above, this may cause confusion with S. strictum or S. papillosum. Both these species differ in colour, basal marginal cells, their papillose leaf cells and exothecial cell shape, and the former differs in its shorter capsules. The most common lowland species of Schistidium in the British Isles. Blom (1996) says that the species is common or very common in artificial habitats and is probably the most common and important species that grows on wall tops throughout much of Europe.

17 S. elegantulum H. H. Blom, Bryophyt. Biblioth., 1996 Dull green mats or tufts, usually somewhat hoary when dry; shoots 1.5–3.0 cm long. Epidermal cells of stems strongly incrassate with small lumens. Leaves imbricate when dry, erect-patent when moist, straight or slightly curved, linearlanceolate to lanceolate, acuminate; margins recurved to 1 /3 –2 /3 way up one side of leaf, plane or more shortly recurved on other side, entire; hyaline points to 1.25 mm long, terete, straight, not flattened below, spinulose, not decurrent down margins; costa smooth on abaxial side above; basal cells rectangular, basal marginal cells quadrate to wider than long, with thickened transverse walls, chlorophyllous, cells above rounded-quadrate to transversely elliptical, incrassate, not or hardly sinuose, smooth, unistratose with bistratose patches, 9–10 μm wide in midleaf. Perichaetial leaves ligulate-lanceolate, concealing capsules in side view or not. Capsules yellow-brown to orange-brown, obloid or shortly cylindrical, 1.6– 2.5 times as long as wide; exothecial cells mostly shortly rectangular in middle and lower half of capsule, walls slightly thickened; peristome teeth orange to red, not curved or twisted, erect-patent to patent when dry, 350–510 μm long, gradually tapering to fine points, with narrow perforations, coarsely papillose above; spores 8–10(−12) μm. Capsules common. Mats or decumbent tufts, hyaline points spinulose-denticulate, costa moderately thick, 45–70 μm wide in middle and lower part of leaf ssp. elegantulum Dense tufts, hyaline points minutely spinulose, costa stout, 75–90 μm wide in middle and lower part of leaf ssp. wilsonii

Ssp. elegantulum (Fig. 134) Mats or decumbent tufts; shoots 1.5–3.0 cm long. Hyaline points 0.3–1.0 mm long, ± pellucid, often yellowish at insertion, terete, spinulose-denticulate; costa 45–70 μm wide and 4–5-stratose towards base; basal cells 12–23 μm long. Hyaline points of perichaetial leaves 0.7–0.9 mm long. Capsules light yellow to light orange-brown; stomata 6–8, peristome teeth orange to orange-red, 350–430 μm long, longly tapering, tips incurved when dry, densely papillose throughout. On sheltered or exposed calcareous rocks, boulders and wall tops. Lowland. Rare, W. Gloucester, Anglesey, Argyll, W. Sutherland, E. Cork. 4, H1. Eurasian

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Fig. 134 1–8, Schistidium elegantulum ssp. elegantulum: 1, shoot with sporophyte; 2, leaves; 3, leaf apex (×40); 4, basal marginal cells (×420); 5, mid-leaf cells (×420); 6, perichaetial leaf; 7, dry empty capsule (×20); 8, exothecial cells (×210). 9–12, S. elegantulum ssp. wilsonii: 9, shoot with sporophyte; 10, leaves; 11, leaf apex (×40); 12, perichaetial leaf. Shoots ×12, leaves ×20.

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Boreo-temperate. Europe from the Pyrenees, Italy and the Crimea north to S. W. Norway, Caucasus, Turkey, Pakistan, Altai, China, Japan, Mexico. Ssp. wilsonii H. H. Blom, Bryophyt, Biblioth., 1996 (Fig. 134) Dense tufts, 1.3–5.0 cm high. Hyaline points 0.55–1.25 mm long, whitish, coarse, terete, spinulose with very small spinulae; costa stout, 75–90 μm wide and 5–7stratose below; basal cells 25–44 μm long. Hyaline points of perichaetial leaves 1.0–1.5 mm long. Capsules orange brown to light reddish brown; stomata 8–16; peristome teeth red, 370–510 μm long, tips not incurved when dry, longly tapering, smooth below, densely papillose above. On limestone boulders, outcrops, cliffs and especially on man-made basic substrates. Lowland. Rare, Hereford, Worcester, Glamorgan, Skye, Clare, W. Galway, E. Mayo. 4, H3. Suboceanic Temperate. Rare in Europe S. W. Norway, Croatia, Faeroes, Italy, Majorca, Portugal, Spain. S. elegantulum is the least common of the Schistidium species formerly included in S. apocarpum. In ssp. wilsonii the costae are conspicuously stout and the spinulae of the hyaline points are very small, barely detectable under the low power of the microscope.

Species of Schistidium likely to occur in the British Isles Species omitted from the following accounts are those with an arctic or eastern distribution, but in view of the presence in the British Isles of species such as S atrofuscum or S. frigidum var. havaasii almost any of the species described by Blom (1996) might occur. The descriptions below are taken from Blom (1996) and Blom (in Nyholm, 1998) and are not based upon original observations. Apocarpum subgroup S. flexipile (Lindb. ex Broth.) Roth: Close to S. apocarpum, but leaves lanceolate; margins strongly recurved, entire; hyaline points not decurrent; basal cells narrowly rectangular, strongly sinuose. Subperichaetial leaves conspicuously different from leaves below. Peristome teeth orange-brown. On exposed montane and lowland rocks. S. lancifolium (Kindb.) H. H. Blom: Upper leaves curved and contorted when dry; margins with irregular teeth above, teeth consisting partly of whole cells; hyaline points short or absent; costa coarsely papillose on abaxial side. Moist rocks in woods and ravines. S. trichodon var. nutans H. H. Blom: see under S. trichodon (p. 408). Strictum subgroup S. boreale Poelt: Similar to S. papillosum and S. pruinosum. Plants usually black. Leaf cells strongly sinuose with dark red walls. Peristome teeth not curved or twisted, 220–320 μm long. Dry calcareous montane rocks. S. confusum H. H. Blom: Similar to S. papillosum and S. pruinosum. Plants dull green to brownish, basal cells wider (9–14 μm vs. 7–11 μm) wide), ± strongly sinuose cells immediately above wider (10–12 μm vs. 6–11 μm wide), mid-leaf cells 8–11 μm wide, cells above weakly papillose. Peristome teeth not curved or twisted. Exposed calcareous montane rocks.

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Robustum group S. subjulaceum H. H. Blom: Upper leaves of fertile shoots appressed and sheathing; hyaline points short, thin, decurrent or not; cells incrassate with orange walls. Capsules 1.4– 2.0 times as long as wide. Base-rich rocks in and beside mountain streams. Confertum group S. venetum H. H. Blom: Cells at widest part of leaf above esinuose, basal cells in oblique lines diverging from costa, basal marginal cells hyaline, forming border, cells above partially bistratose, often opaque. On base-rich soil on mountain cliffs and ledges. Umbrosum group S. pulchrum H. H. Blom: Stem epidermal cells strongly incrassate with small lumens. Hyaline points conspicuously white; margins strongly recurved or revolute above; costa not widened above. Capsules 1.2–1.8 times as long as wide; exothecial cells quadrate, rectangular or transversely rectangular in patches; peristome teeth bright red, entire or with slits, finely papillose. On dry or moist rocks in humid situations on mountains. S. umbrosum (Zetterst.) H. H. Blom: Similar to S. pulchrum but plants intricately branched; costa widened above. Capsules 1.1–1.3 times as long as wide; peristome teeth dull red, strongly perforated, coarsely papillose. In crevices of ± vertical montane cliffs. Atrofuscum group S. singarense (Schiffn.) Laz.: Plants usually jet black. Stem epidermal cells slightly thickened, lumens large. Leaves obtusely keeled above; hyaline points short, coarse, terete, not decurrent, coarsely spinulose; basal marginal cells chlorophyllous or subhyaline, transverse walls sometimes thickened. Capsules 1.6–2.3 times as long as wide; exothecial cells very variable in size and shape; peristome teeth strongly perforated. On basic rocks and walls in lowland areas (likely to occur in southern England).

78 GRIMMIA HEDW., SP. MUSC. FROND., 1801 Autoicous or dioicous. Acrocarpous, usually tufted or cushion-forming plants. Stems with or without central strand. Leaves ovate to linear-lanceolate, usually with hyaline points; margins plane, incurved or recurved; costa in section semiterete, reniform or poorly differentiated from lamina; basal cells quadrate to linear, sinuose or not, sometimes nodulose, frequently hyaline towards margins, cells above usually isodiametric, often incrassate and sinuose, 1–3(−5)-stratose, usually smooth or occasionally bulging, very rarely papillose. Perichaetial leaves usually similar to but larger than vegetative leaves or rarely strongly differentiated, hyaline and filmy. Setae straight or curved; capsules exserted or immersed, smooth or ribbed; annulus present; columella not falling with lid; exothecial cells isodiametric to narrowly rectangular; peristome teeth entire or variously perforated or divided above, segments not filiform; calyptrae mitrate or cucullate, not

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plicate, 2–3 cells thick, covering lid. A cosmopolitan genus of c. 70 almost exclusively saxicolous species. Derivation: Named after a German physician and botanist, J. F. Grimm (1737–1821). A difficult genus because of the rarity of many of the species and because of taxonomic and nomenclatural confusion. For a well illustrated account of central European Grimmia species, which includes most British taxa, see E. Maier & P. Geissler, Herzogia 11, 1–80, ˜ & F. Pando, 1995. A very usable key to the world’s Grimmia species is provided by J Munoz Mon. Syst. Bot., Missouri Bot. Gard., 83, 1–133, 2000. Also very useful is an account of Latin ˜ American species by J. Munoz, Ann. Missouri Bot. Gard. 85, 367–403, 1996. For a monograph of European species see Greven (1995). Many Grimmia species have decreased in the British Isles over the past 150 years, partly because of over-collecting and partly because of atmospheric pollution. There are copious old gatherings of species from localities in which they now no longer occur. Many species are very slow growing and lack any obvious means of propagation and great care should be exercised when collecting material to minimise the possibility of further extinctions.

1 Leaves without hyaline points 2 At least uppermost vegetative leaves and perichaetial leaves with some trace of hyaline points 4 2 Basal part of leaves ovate, pellucid, abruptly narrowed into narrowly lingulate, very opaque upper part, margins erect 6. G. unicolor Leaves tapering from widest part to apex, ± pellucid above, margins recurved on one or both sides 3 3 Costa not winged on abaxial side above, basal cells near costa 1–4 times as long as wide, setae straight 14. G. atrata Costa winged on abaxial side above, basal cells linear, setae arcuate when moist 26. G. ramondii 4 Basal marginal cells of leaves uniformly thin-walled 5 Basal marginal cells of leaves with transverse walls more heavily thickened than longitudinal walls 8 5 Leaves crisped when dry, narrowly lanceolate or ligulate from ovate basal part 19. G. incurva Leaves straight to flexuose when dry, ovate to lanceolate 6 6 Leaves of ± uniform size up stems, hyaline points very short, to 160 μm long in upper leaves, capsules unknown in Britain 12. G. elongata Upper leaves much longer than lower, hyaline points to as long as or longer than lamina in upper leaves, capsules very common 7 7 Setae straight, capsules erect, leaves not homomallous when dry 10. G. donniana Setae curved when moist, capsules ± horizontal, leaves homomallous when dry 11. G. arenaria 8 Plants brownish, leaves spirally crisped when dry 17. G. torquata Plant colour various, leaves straight or flexuose when dry 9 9 Capsules immersed, inclined, gibbous, leaves strongly concave 10

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Capsules exserted or if immersed then erect and symmetrical or capsules lacking, leaves concave or not 11 Capsules gymnostomous, leaves widest below middle, mid-leaf cells 8–10 μm wide 1. G. anodon Capsules peristomate, leaves widest above middle, mid-leaf cells 10–12 μm wide, 2. G. crinita Cells in upper part of leaf conspicuously papillose, opaque 25. G elatior Leaf cells smooth, pellucid or opaque 12 Leaves channelled above, costa poorly defined, not conspicuous on abaxial side of leaf, in section hardly distinct from lamina cells, lamina cells 2−4-stratose, opaque 13 Leaves keeled above, costa well defined, conspicuous on abaxial side of leaf, in section ± semiterete or reniform, not grading into lamina cells, lamina cells 1−2-stratose, pellucid or opaque 15 Leaves acuminate, basal cells near costa 4–8 times as long as wide 5. G. ovalis Leaves obtusely pointed, basal cells near costa 0.5–2.0 times as long as wide 14 Basal marginal cells of leaves to twice as wide as long, capsules exserted 3. G. laevigata Basal marginal cells 1–2 times as long as wide, capsules immersed 4. G. tergestina Leaf margins plane or incurved, cells in upper half of leaf opaque 16 Leaf margins at least partially recurved on one or both sides, cells pellucid or opaque 18 Lamina cells bulging in transverse section, 8–13 μm wide in mid-leaf, capsules fusiform, exothecial cells thick-walled 9. G. alpestris Lamina cells not bulging in section, 5–8 μm wide in mid-leaf, capsules ovoid or ellipsoid, exothecial cells thin-walled 17 Dioicous, setae 2–4 mm long, capsule lids rostrate, acute, peristome teeth 50–90 μm wide at base, basal marginal cells 2.0–4.5 times as long as wide 7. G. montana Autoicous, setae to 2 mm long, lids bluntly mamillate, peristome teeth 40–50 μm wide at base, basal marginal cells 1–2 times as long as wide 8. G. ungeri Leaves abruptly narrowed into hyaline points so that apices are ± obtuse, capsules common 19 Leaves tapering into hyaline points, acuminate, capsules rare (except G. decipiens) 20 Basal cells of leaves 2–4 times as long as wide, capsules ellipsoid, lids usually rostrate, perigonia inconspicuous, immediately beneath perichaetia, outer perigonial bracts much modified, filmy, orange, muticous, ecostate 15. G. pulvinata

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Basal cells 4–8 times as long as wide,1 capsules ± spherical, lids mamillate, perigonia conspicuous, terminal on branches, outer perigonial bracts unmodified, similar to stem leaves, green 16. G. orbicularis Plants dark grey, leaves spirally imbricate when dry giving shoots string-like appearance, flagelliform shoots often present 18. G. funalis Colour various, leaves if imbricate then not spirally so when dry, flagelliform shoots lacking 21 Costa reniform in section, poorly defined above, lamina cells opaque above, setae straight 13. G. longirostris Costa ± semiterete in section, clearly defined above, lamina cells pellucid, setae arcuate when moist 22 Hyaline points to as long as lamina in upper leaves, strongly denticulate, decurrent down margins, basal cells near costa to 10 times as long as wide, upper cells strongly sinuose, capsules common 24. G. decipiens Hyaline points not as above, basal cells near costa 2–6(−8) times as long as wide, upper cells esinuose to sinuose, capsules rare 23 Upper leaves secund when moist, clusters of brown gemmae often present at shoot tips 23. G. hartmanii Upper leaves patent to squarrose when moist, clusters of gemmae lacking 23 Costa section 2 cells wide on adaxial side, at extreme base with two layers of guide cells, plants calcifuge 20. G. trichophylla Costa section 4 cells wide on adaxial side, at extreme base with one layer of guide cells, plants of acidic or strongly basic habitats 25 Leaves patent to spreading when moist, costa section at extreme base with 4 guide cells, plants calcicole 21. G. dissimulata Leaves usually recurved to squarrose when moist, costa section at extreme base with 6 guide cells, plants calcifuge 22. G. lisae

Subgenus 1 Grimmia Leaf cells unistratose or bistratose above. Setae less than 1 mm long, curved; capsules globose, smooth or weakly ribbed, gibbous, gymnostomous or not. 1 G. anodon Bruch & Schimp. in Bruch et al., Bryol. Eur., 1845 (Fig. 135) Autoicous. Small dark green cushions, hoary when dry, to 1.5 cm high. Leaves appressed when dry, patent when moist, keeled, oblong-lanceolate to oblongobovate, obtuse; margins recurved at middle of leaf; hyaline points to as long as lamina, smooth to denticulate, often decurrent down margins; costa 2 cells wide on adaxial side in section; basal cells rectangular, hyaline, basal cells next to costa 2–4 times as long as wide, basal marginal cells 1–2 times as long as wide, transverse walls thicker than longitudinal walls, cells above quadrate, bistratose at margins and towards apex, 8–10 μm wide in mid-leaf. Setae c. 0.4 mm long, curved; capsules immersed, inclined, ± globose, gibbous, wide-mouthed when 1

In British Isles material.

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Fig. 135 1–5, Grimmia anodon: 1, leaves; 2, section of costa in lower part of leaf; 3, basal marginal cells; 4, mid-leaf cells; 5, capsule. 6–10, G. crinita: 6, leaves; 7, section of costa in lower part of leaf; 8, basal marginal cells; 9, mid-leaf cells; 10, capsule. Leaves ×30, sections ×280, cells ×420, capsules ×10.

empty; peristome absent; spores 8–10 μm. Capsules common, spring. In crevices of exposed vertical calcareous rock on cliffs and on walls. 150–250 m. Probably extinct, Westmorland (1960s, now extinct), Midlothian (1869). 2. GB1 + 1∗ . Circumpolar Wide-temperate. Europe north to Svalbard, Caucasus, Turkey, Iran, Saudi Arabia, C. and N. Asia, Tenerife, Algeria, Morocco, Egypt, N. America, Greenland, Mexico, Peru, Bolivia, Patagonia. Most likely to be confused with Coscinodon cribrosus or Schistidium flaccidum. The former has erect capsules with peristomes and plicate leaves. S. flaccidum has erect capsules and narrowly lanceolate leaves. Other Schistidium species differ in their erect capsules with peristomes, leaf shape and areolation. G. anodon has also been confused with G. tergestina, which is dioicous and has different leaf areolation. For a discussion of the distribution of G. anodon in Britain see T. L. Blockeel, J. Bryol. 19, 181–4, 1996.

2 G. crinita Brid., Muscol. Recent. Suppl. 1, 1806 (Fig. 135) Grey patches, to c. 1 cm high, resembling mouse fur when dry. Shoots julaceous when moist. Leaves concave, ovate-lanceolate to obovate, abruptly narrowed into hyaline point; margins plane; hyaline points in upper leaves as long as or longer than lamina, flattened at base, terete above, smooth; costa 2 cells wide on adaxial side in section; basal cells hyaline, cells next to costa 1.0–1.5 times as long as wide,

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basal marginal cells 2–3 times as long as wide, transverse and longitudinal walls of similar thickness, cells above shortly rectangular to quadrate, incrassate, sinuose, unistratose throughout, 10–12 μm wide in mid-leaf. Setae c. 1 mm long, curved; capsules ± immersed in points of perichaetial leaves, inclined, ovoid, smooth or weakly ribbed, gibbous; peristome present; spores 10–12 μm. Capsules common. On limestone rocks and mortar. Lowland. Recorded from a dry mortared wall of a canal bridge near Hatton, Warwickshire, between 1872 and 1882, but not seen again in England until a recent discovery in E. Cornwall, Dublin (1950) 2, H1. GB1 + 1∗ , IR1. Submediterranean-Subatlantic. Europe, extending north to Poland and Baltic Russia, Caucasus, Israel, Lebanon, Algeria. Known from Warwickshire from 1872 to 1882 and thought to be an introduction, but found on a concrete wall in Cornwall in 1999. There is also a specimen from Dublin, collected in 1950, so it seems likely that G. crinita is native to the British Isles.

Subgenus 2 Guembelia Schimp., Coroll. Bryol. Eur., 1856 Leaves concave, ± ovate, not keeled; margins plane or incurved above; costa obscure above; cells above 2 or more stratose, opaque. Capsules erect, symmetrical, immersed or exserted; annulus of large reddish separating cells. 3 G. laevigata (Brid.) Brid., Bryol. Univ, 1826 G. campestris Burchell ex Hook., G. leucophaea Grev.

(Fig. 136)

Readily disintegrating tufts or patches, hoary when dry, 0.5–1.5 cm high. Leaves appressed, straight when dry, erect-patent when moist, triangular to lanceolate with broad base, apex obtuse; margins plane or erect; hyaline points in upper leaves to as long as or longer than lamina, flattened, finely denticulate, decurrent down margins; costa broad at base, narrower and poorly defined above, several cells wide on adaxial side in section; cells incrassate, esinuose, bistratose, opaque except near base, basal cells near costa twice as long as wide, basal marginal cells transversely oblong, to twice as wide as long, transverse walls thicker than longitudinal walls, cells above quadrate or wider than long, 6–10 μm wide in mid-leaf. Setae straight; capsules ellipsoid, smooth; spores 10–15 μm. Capsules rare, spring. n = 13. On acidic or slightly basic rocks, cliffs, outcrops by rivers, sarsen stones and roofing slates, especially in coastal areas. 0–350 m. Scattered localities from Cornwall east to Kent and north to Angus and Skye, W. and E. Cork, Antrim, Jersey, Guernsey. 33, H3, C. GB21 + 30∗ , IR1 + 4∗ , C6. Circumpolar Southerntemperate. From Mediterranean region north to S. Fennoscandia, Turkey, Cyprus, Caucasus, temperate and tropical Asia, Macaronesia, N. Africa, N. America, Argentina, Brazil, Chile, Australasia, Hawaii. This species can withstand extremes of drought and is tolerant of some degree of pollution. It is, however, decreasing, except in southern England where it has increased in recent years.

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Fig. 136 1–6, Grimmia laevigata: 1, leaves 2, costa section in lower part of leaf; 3, basal marginal cells; 4, basal cells next to costa; 5, mid-leaf cells; 6, capsule. 7–12, G. tergestina: 7, leaves; 8, costa section in lower part of leaf; 9, basal marginal cells; 10, basal cells next to costa; 11, mid-leaf cells; 12, capsule. Leaves ×20, sections ×280, cells ×420, capsules ×10.

4 G. tergestina Tomm. ex Bruch & Schimp. in Bruch et al., Bryol. Eur., 1845 (Fig. 136) Dioicous. Blackish green, readily disintegrating tufts or patches, hoary when dry, to 1 cm high. Leaves erect when dry, erect-patent when moist, concave, ovatelanceolate, obtuse; margins plane below, ± incurved above; hyaline points in upper leaves to as long as or longer than lamina, smooth or slightly denticulate, flattened, decurrent down margins; costa poorly defined, several cells wide on adaxial side in section; cells incrassate, basal cells by costa 2–3 times as long as wide, towards margins hyaline, basal marginal cells, 1–2 times as long as wide, transverse walls much more strongly thickened than longitudinal walls, cells above bistratose, opaque, rounded-quadrate, 6–12 μm wide in mid-leaf. Setae straight; capsules

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immersed, erect, ovoid, smooth; peristome present; spores 8–10 μm. Capsules occasional. On dry exposed basic rocks. Very rare, Argyll, Mull. 2. GB4. Eurasian Southern-temperate. S., C. and W. Europe extending north to the Netherlands and Gotland (Sweden), Asia, Tenerife, N. Africa, N. America, Caribbean, Bolivia, Peru. Macroscopically similar to G. laevigata but differing in the smooth or slightly denticulate hyaline points and the basal marginal cells longer than wide with strongly thickened transverse walls. It has been confused with G. anodon, which has pellucid cells in the upper part of the leaf and the usually present immersed inclined asymmetrical capsules. For an account of G. tergestina in Scotland see H. C. Greven, J. Bryol. 18, 499–502, 1995. This species is considered a recent arrival in N. W, France, Belgium and the Netherlands (although there is no evidence for this) but the Scottish plants appear to be of long standing (see T. L. Blockeel, J. Bryol. 19, 189–91, 1996). This species is treated as vulnerable in the Red List of British Mosses.

5 G. ovalis (Hedw.) Lindb., Acta Soc. Sci. Fenn., 1871 G. commutata Huebener, G. ovata F. Weber & D. Mohr

(Fig. 137)

Dioicous. Dark green to blackish tufts or cushions, sometimes hoary when dry, (0.5−)1.0–4.0 cm high. Leaves loosely appressed, straight when dry, erect-patent when moist, concave, from ovate ± sheathing basal part narrowed to lanceolate or narrowly lanceolate acuminate upper part, channelled above; margins plane; hyaline points to as long as lamina in upper leaves, flattened below, terete above, weakly denticulate; costa poorly defined, wide below, scarcely protruding on abaxial side, obscure above, ending in apex, in section several cells wide adaxially and scarcely distinct from lamina cells; basal cells near costa incrassate and esinuose to strongly incrassate and sinuose, 4–8 times as long as wide, basal marginal cells (1−)2–3 times as long as wide, transverse walls thicker than longitudinal walls, cells above irregularly quadrate, incrassate, 2–4-stratose, opaque, 6–8 μm wide in mid-leaf. Setae straight; capsules ovoid, smooth, narrowed at mouth; exothecial cells irregularly rectangular, thin-walled; lid obliquely rostrate; spores 9–12 μm. Capsules rare, spring. n = 13. On acidic or neutral rocks and roofing tiles. At low altitudes. Very rare and decreasing, E. Sussex, W. Kent, N. Essex and a few scattered localities from W. Gloucester and E. Wales north to Sutherland. 25. GB15 + 28∗ . Circumpolar Boreo-temperate. Europe north to c. 68◦ N, temperate and tropical Asia, Canary Islands, Madeira, N. Africa, N. America, Mexico, Guatemala. Although confused nomenclaturally and taxonomically in the past with G. longirostris, G. ovalis is readily distinguished by the leaves channelled above, the plane margins and the costa section. This species is treated as vulnerable in the Red List of British Mosses.

6 G. unicolor Hook. in Grev., Scott. Crypt. Fl., 1825 (Fig. 137) Dioicous. Dark green tufts, 2–5 cm high; stems ± unbranched. Leaves appressed when dry, patent when moist, from pellucid ovate basal part narrowed to opaque narrowly lingulate obtuse ± cucullate upper part, channelled above, margins plane

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Fig. 137 1–7, Grimmia ovalis: 1, leaves (×20); 2, costa section in lower part of leaf; 3, costa section in upper part of leaf; 4, basal marginal cells; 5. basal cells next to costa; 6, mid-leaf cells; 7, capsule. 8–13, G. unicolor: 8, leaves (×35); 9, costa section in lower part of leaf; 10, basal marginal cells; 11, basal cells next to costa; 12, mid-leaf cells; 13, old capsule. Sections ×280, cells ×429, capsules ×15.

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below, erect above; hyaline points absent; costa strong below, very obscure above, in section several cells wide on adaxial side distinct from lamina cells; basal cells near costa thick-walled, 5–10 times as long as wide, basal marginal cells hyaline, 4–10 times as long as wide, longitudinal walls very thin, transverse walls thicker, cells above irregularly quadrate, very incrassate, sinuose, 2–4-stratose, very opaque, c. 8 μm wide in mid-leaf. Setae straight; capsules ovoid to ovate-ellipsoid, smooth; lid longly rostrate; spores 10–12 μm. Capsules occasional, spring. Wet sloping schist rock. 470 m. Very rare, Angus. 1. GB1 + 1∗ . European Boreal-montane. Montane and northern Europe to about 68◦ N, Caucasus, Siberia, Mongolia, Kashmir, N. America. Unlikely to be mistaken for any other moss, the broad pellucid basal part narrowed into the opaque narrowly lingulate channelled ± cucullate upper part being characteristic. It is reported from C. Europe that if the substrate becomes dry the leaves of this plant may ˜ develop hyaline points, but all such specimens have proved to be stunted G. ovalis (J. Munoz, pers. commun.). This species is treated as vulnerable in the Red List of British Mosses and is protected under the Wildlife and Countryside Act.

Subgenus 3 Orthogrimmia Schimp., Coroll. Bryol. Eur., 1856 Leaves keeled above; margins plane or incurved; costa well defined above; basal marginal cells often with thickened transverse walls, cells above bistratose, opaque. Setae straight (except G. arenaria), smooth; annulus of small cells, persisting or separating individually. Section 1 Montanae I. Hagen, Kongel. Norske Vidensk. Selsk. Skr. (Trondheim), 1909 Basal marginal cells of leaves not hyaline, with thickened longitudinal walls and more strongly thickened transverse walls. Annulus persisting; calyptrae cucullate. 7 G. montana Bruch & Schimp. in Bruch et al., Bryol. Eur., 1845 (Fig. 138) Small dense dark green to blackish cushions or patches, sometimes hoary when dry, to 1 cm high. Leaves erect, appressed, flexuose when dry, erect-patent when moist, from ovate to ovate-lanceolate basal part narrowed to lanceolate to linearlanceolate channelled upper part, keeled towards apex; margins plane below, incurved above; hyaline points 1/2 –3/4 (−1) length of lamina in upper leaves, entire or denticulate; costa stout, well defined, prominent abaxially, 2 cells wide in adaxial side in section; basal cells thick-walled, esinuose, near costa and margins 2.0–4.5 times as long as wide, marginal cells with transverse walls thicker than longitudinal walls, cells above irregularly quadrate, incrassate, slightly sinuose, 2–3(−4)-stratose, opaque, in section not bulging, 8–10 μm wide in mid-leaf. Setae straight, 2–4 mm long; capsules ovoid, ± abruptly narrowed into seta, smooth, without stomata at base; exothecial cells irregularly rectangular, thinwalled, peristome teeth of similar colour to capsule, 50–90 μm wide at base, perforated and cleft; lid rostrate, acute; spores c. 12 μm. Capsules rare, spring. n = 13.

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Fig. 138 1–7, Grimmia montana: 1, leaves (×20); 2, section of costa in lower part of leaf; 3, basal marginal cells; 4, basal cells next to costa; 5, mid-leaf cells; 6, capsule; 7, exothecial cells. 8–14, G. ungeri: 8, leaves (×20); 9, section of costa in lower part of leaf; 10, basal marginal cells; 11, basal cells next to costa (×420); 12, mid-leaf cells; 13, capsule; 14, exothecial cells. Sections and exothecial cells ×280, leaf cells ×420, capsules ×15.

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On exposed, acidic to basic rocks. 0–500 m. Rare and decreasing, scattered localities in W. and N. Britain from S. Devon north to S. Aberdeen and Argyll, Jersey. 20, C. GB18 + 14∗ , C2∗ . Circumpolar Temperate. Europe north to Fennoscandia, Iceland, Caucasus, Turkey, N. and C. Asia, China, Macaronesia, Morocco, western N. America, Greenland, Mexico. Readily distinguished from G. ungeri when capsules are present but sterile plants differ only in the length of the basal marginal cells and the more longly tapering leaves channelled above as a consequence of the incurved margins. Poorly developed specimens may be impossible to name. Sporophytes are rare in G. montana but common in G. ungeri.

8 G. ungeri Jur. in Unger & Kotschv., Ins. Cypern, 1865 (Fig. 138) G. alpestris auct. Angl. non (F. Weber & D. Mohr) Schleich., G. sessutana auct. Non De Not. Autoicous. Blackish green tufts or patches, to 1 cm high. Leaves ± erect when dry, erect-patent when moist, ovate-lanceolate, keeled above; margins incurved above and sometimes partially recurved below; hyaline points to as long as lamina in upper leaves, denticulate; costa stout, well defined or not, ± prominent abaxially, in section 2 cells wide on adaxial side; basal cells of ± same length from costa to margins, mostly 1–2 times as long as wide, towards margins more hyaline with thickened transverse walls, cells above irregularly quadrate, incrassate, sinuose, bistratose, opaque, c. 8 μm wide in mid-leaf. Setae straight, 1–2 mm long; capsules ovoid, ± abruptly narrowed into seta, smooth, stomata lacking at base; exothecial cells isodiametric and rectangular mixed, thin-walled; lid mamillate, blunt; peristome teeth of similar colour to capsule, 40–50 μm wide at base; spores 8–10 μm. Capsules common, spring, summer. On dry serpentine rocks. 580 m. Very rare, Angus (old record), Aberdeen. 3. GB2 + 1∗ . Sardinia, Cyprus, Tenerife, common in western N. America, Quebec, Mexico. The first Scottish gathering of this plant was named G. ungeri by its collector, Rev. J. Fergusson, in 1870 but Scottish material was later referred to as G. alpestris (F. Weber ¨ Hal. (as G. & D. Mohr) Schleich. In 1992, British material was renamed G. reflexidens Mull. sessitana De Not.) by H. C. Greven (J. Bryol. 18, 499–502, 1995). It has since been shown that ˜ the Scottish specimens belong G. ungeri (see J. Munoz, Ann. Missouri Bot. Gard. 85, 367–403, 1998). G. reflexidens differs from G. ungeri in the basal cells of the leaves 2–6 times as long as wide, the exothecial cells ± rectangular, stomata present, and the peristome teeth orange, contrasting with the brown capsule. This species is treated as vulnerable (as G. sessitana) in the Red List of British Mosses.

9 G. alpestris (F. Weber & D. Mohr) Schleich., Cat. Pl. Helv. 1808 Dioicous. Blackish green tufts or patches. Leaves ± erect when dry, erect-patent when moist, ovate-lanceolate, keeled above; margins plane below, incurved above; hyaline points to as long as lamina in upper leaves, hardly denticulate; costa stout, well defined, ± prominent abaxially, in section 2 cells wide on adaxial

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side; basal cells of ± same length from costa to margins, mostly 1.0–3.5 times as long as wide, towards margins more hyaline with thickened transverse walls, cells above irregularly quadrate, incrassate, sinuose, bistratose in upper 1 /3 , opaque, in section bulging, 8–13 μm wide in mid-leaf. Setae straight, 2–4 mm long; capsules fusiform, smooth; exothecial cells isodiametric, thick-walled; lid comical or mamillate, obtuse; peristome teeth 50–70 μm wide at base, of similar colour to capsule; spores 10–14 μm. On exposed siliceous rocks. 780 m. Very rare, Merioneth. 1. GB1. Montane Europe and Asia, N. America. This is the first confirmed (by E. Maier) occurrence of this species in Britain. It as found by J. Werner–Braun (pers. Commun.) in Merioneth in 2004. For a summary of the differences between G. montana, G. ungeri and G. alpestris see A J. E. Smith, Field Bryology 82, 8–10, 2004. G. alpestris (F. Weber & D. Mohr) Schleich. was recorded from Marros, Carmarthenshire (altitude 150 m), a locality where Coscinodon cribrosus occurs. It was later also reported from Pembrokeshire, but that specimen is Coscinodon cribrosus. It seem highly likely that the specimen from Marros also belongs to that species.

Section 2 Donianae (Loeske) J. Munoz, ˜ Ann. Missouri Bot. Gard., 1998 Basal marginal cells hyaline, cell walls uniformly thin. Annulus separating; calyptrae mitrate. 10 G. donniana Sm., Engl. Bot., 1804 (Fig. 139) Autoicous. Small dark green cushions, tufts or scattered plants, hoary when dry, to 1.5 cm high. Leaves loosely appressed, straight when dry, erect-patent when moist, small below, increasing in size up female stems and intergrading with perichaetial leaves, from ovate or narrowly ovate, ± hyaline basal part narrowed into or tapering into lanceolate or narrowly lanceolate, keeled, acute or acuminate upper part; margins often incurved near base, plane above; hyaline points in lower leaves short, increasing in length up stems, in upper and perichaetial leaves to as long as or longer than lamina, flattened below, terete above, denticulate; costa strong below, well defined above, prominent on abaxial side, 2 cells wide on adaxial side in section; basal cells thin-walled or occasionally somewhat thickened towards costa, near costa and towards margins 4–6(−8) times as long as wide, marginal cells uniformly very thin-walled, cells above quadrate, incrassate, ± sinuose, bistratose, opaque, 10–12 μm wide in mid-leaf. Perichaetial leaves with hyaline points flexuose, not twisted. Setae straight; capsules emergent to exserted, pale brown, ovoid, smooth, with stomata at base; lid conical or shortly rostrate, blunt; spores 10–12 μm. Capsules common, spring to autumn. n = 12 + m, 13∗ . In exposed situations in crevices of hard acidic especially slatey rocks on cliffs, in scree, on mine and quarry waste and walls, often where heavy metals are present, in montane areas. 0–950 m. Rare in S. W. England, frequent or common in N. Wales, N. W. England and Scotland as far north as S. Aberdeen and W. Inverness, rare or occasional further north to Shetland, rare in Ireland. 53, H14. GB198 + 91∗ , IR14 + 9∗ . European Boreo-arctic Montane. Europe north to Svalbard, Iceland, Caucasus, Turkey,

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Fig. 139 1–6, Grimmia donniana: 1, leaves (×20); 2, costa section in lower part of lead; 3, basal marginal cells; 4, basal cells next to costa; 5, mid-leaf cells; 6, capsule. 7–12, G. arenaria: 7, leaves (×25); 8, costa section in lower part of leaf; 9 basal marginal cells; 10, basal cells next to costa; 11, mid-leaf cells; 12, capsule. 13–17, G. elongata: 13, leaves (×20); 14, costa section in lower part of leaf; 15, basal marginal cells; 16, basal cells next to costa; 17, mid-leaf cells. Sections ×380, cells ×420, capsules ×15.

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Himalayas, temperate Asia, Madeira, Tenerife, E. Africa, N. America, Greenland, Mexico, Ecuador, Bolivia, Antarctica. By far the commonest of the Grimmia species with erect capsules. Attention is usually first drawn to this plant because of the numerous pale brown capsules. The only other species likely to be confused with G. doniana are G. arenaria (q.v.), G. alpestris and G. ungeri, all of which are very rare. The very-thin-walled basal marginal cells will separate G. donniana and G. arenaria from other species except G. elongata and G. incurva. The former has very short hyaline points and the latter leaves crisped when dry.

11 G. arenaria Hampe, Linnaea, 1836 (Fig. 139) G. donniana var. arenaria (Hampe) Loeske, G. donniana var. curvula Spruce Autoicous. Small dark green tufts or patches, hoary when dry, with homomallous leaf tips giving plants a brushed appearance, to 1 cm high. Leaves loosely appressed when dry, erect-patent when moist, small below, increasing in size up stems and intergrading with perichaetial leaves, from ovate or narrowly ovate, ± hyaline basal part narrowed into or tapering into lanceolate or narrowly lanceolate, keeled, acute or acuminate upper part; margins often incurved near base, plane above; hyaline points in lower leaves short, increasing in length up stems, in upper and perichaetial leaves to as long as or longer than lamina, flattened below, terete above, denticulate, often homomallous; costa strong, well defined, prominent abaxially, 2 cells wide on adaxial side in section; basal cells thin-walled, near costa and towards margins 4–10 times as long as wide, basal marginal cells uniformly very thin-walled, cells above quadrate, incrassate, sinuose, bistratose, opaque, 10–12 μm wide in mid-leaf. Perichaetial leaves longer than vegetative leaves, with sheathing bases; hyaline points flexuose, twisted. Setae curved, ± burying capsules in hyaline points of perichaetial leaves; capsules ± horizontal, ovoid, smooth; lid mamillate; spores 10–12 μm. Capsules common, spring, autumn. n = 13∗ . Crevices in walls and hard acidic rocks, especially where slatey, in sheltered situations. Lowland. Occasional in Merioneth, very rare elsewhere, Cardigan, Caernarfon, Denbigh (old record), Cumberland. 5. GB6 + 5∗ . Suboceanic Temperate. Rare in Europe from Spain, Italy and Romania north to Norway and Finland. Treated as a variety of G. donniana by recent authors but is a distinct species, there being no intermediates (see Greven, 1995). It differs from all other British Grimmia species in the leaf tips homomallous when dry, giving the plants a brushed appearance, and the capsules ± horizontal amongst the perichaetial leaves. G. hartmanii, which has secund leaves, differs in habitat, habit and short hyaline points. Although the setae are curved, G. arenaria will not be mistaken for a member of subgenus Rhabdogrimmia as they have setae arcuate when moist

Section 3 Elongatae With the characters of G. elongata.

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12 G. elongata Kaulf. in Sturm., Deutschl. Fl. Abt. 2, Crypt., 1815 (Fig. 139) Dioicous. Brownish green readily disintegrating, erect or depressed tufts, shoots to 2 cm long. Leaves of ± uniform length along stems, ± straight to slightly twisted when dry, erect-patent when moist, lanceolate to narrowly lanceolate, keeled above, apex obtuse; margins narrowly recurved on one or both sides below or plane; hyaline points lacking in lower leaves, very short in upper, to 150 μm long, smooth; costa well defined, ending in or below apex, 2 cells wide on adaxial side in section; basal cells thin-walled, near costa 3–6 times as long as wide, basal marginal cells 4–6(−10) times as long as wide, hyaline uniformly thin-walled, cells above irregularly quadrate, incrassate, strongly sinuose, 1–2-stratose, opaque, c. 8 μm wide in mid-leaf. Setae straight; capsules ovoid; spores 12–15 μm. Capsules unknown in Britain. On exposed dry or damp montane rocks. 500–1080 m. Very rare, Caernarfon, Westmorland, Cumberland, S. Aberdeen, old records from N. Northumberland and Angus. 6. GB6 + 4∗ . Circumpolar Arctic-montane. Montane and northern Europe north to c. 67◦ N, Iceland, Caucasus, Turkey, Sikkim, Siberia, China, Taiwan, Japan, N. Africa, N. America, Greenland, Latin America. Recognised by the very short hyaline points and the uniformly thin-walled basal marginal cells.

Subgenus 4 Atratae (Bruch & Schimp.) Leaf margins recurved above; basal cells near costa elongate, becoming shorter towards margins, cells above 1–2-stratose, opaque. Setae straight; capsules erect, smooth; annulus of 3–5 rows large separating cells. 13 G. longirostris Hook., Musci Exot., 1818 (Fig. 140) ¨ G. affinis Hornsch., G. ovalis auct. non (Hedw.) Limpr., G. ovata Schwagr. Autoicous. Small compact tufts or cushions, sometimes hoary when dry, 1.0– 1.5(−2.5) cm high. Leaves ± erect, straight when dry, erect-patent when moist, ovate-lanceolate to lanceolate, tapering from widest part to acuminate apex, channelled above; margins narrowly recurved in middle region of leaf on one or rarely both sides; hyaline points 1/4 –2/3 (−1) length of lamina in upper leaves, smooth to slightly denticulate, not or hardly decurrent; costa strong below, obscure above, hardly prominent on abaxial side, in section reniform, with U-shaped sinus and 4–8 cells wide on adaxial side; basal cells near costa with thick nodulose longitudinal walls, thin transverse walls, 3–6 times as long as wide, marginal cells hyaline, 1–3 times as long as wide, longitudinal walls thin, transverse walls thick, cells above rectangular to quadrate, very sinuose, incrassate, unistratose, ± pellucid, at margins 1–2-stratose, in mid-leaf 8–12 μm wide. Perichaetial leaves similar to upper vegetative leaves but with expanded sheathing basal part. Setae straight; capsules barely emergent above perichaetial leaves to exserted, ovoid to cylindrical, smooth; exothecial cells rectangular, thinwalled; annulus separating; lid mamillate to longly rostrate; spores 10–12 μm.

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Fig. 140 1–7, Grimmia longirostris: 1, leaves (×20); 2, costa section in lower part of leaf; 3, costa section in upper part of leaf; 4, basal marginal cells; 5, basal cells next to costa; 6, mid-leaf cells; 7, capsule. 8–13, G. atrata: 8, leaves (×30); 9, costa section in lower part of leaf; 10, basal marginal cells; 11, basal cells next to costa; 12, mid-leaf cells; 13, capsule. Sections ×280, lamina cells ×429, capsules ×15.

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Capsules frequent, winter. n = 13. On dry exposed acidic or basic rocks, cliffs and scree. 0–550 m Very rare and declining, W. and N. Britain from Devon north to W. Sutherland, S. Kerry, old records from Mid Cork, Down and Antrim. 22, H4. GB19 + 21∗ , IR1 + 4∗ . Circumpolar Boreo-temperate. World-wide except for Antarctica. The costa reniform with U-shaped adaxial sinus in transverse section provides an absolute character separating G. longirostris from all other Grimmia species. The long incrassate basal cells near the costa and the leaves channelled rather than keeled above are also useful ˜ distinguishing characters. For a detailed account of G. longirostris see J. Munoz, Ann. Missouri Bot. Gard. 85, 352–65, 1998. Because of nomenclatural and taxonomic confusion some records of G. longirostris may belong to G. ovalis. Other specimens referred to G. britannica or G. austrofunalis (see under G. trichophylla) belong here.

14 G. atrata Miel. ex Hornsch., Flora, 1819 (Fig. 140) Dioicous. Greenish black tufts, 1–4(−7) cm high. Stems radiculose below. Leaves flexuose to ± crisped when dry, erect to erect-patent when moist, narrowly ligulate, narrowly lanceolate or from narrowly ovate basal part narrowed to ligulate upper part, obtuse, channelled above; margins narrowly recurved on one or both sides below; hyaline points absent; costa strong, prominent on abaxial side, ending in apex, several cells wide on adaxial side in section; cells at extreme base with ± straight walls, above becoming incrassate, strongly nodulose, basal cells near costa incrassate, 1–4 times as long as wide, 2–3 rows of basal marginal cells hyaline, 1–3 times as long as wide, longitudinal walls very thin, transverse walls thicker, cells above quadrate, thin-walled to incrassate and sinuose, smooth, unistratose with bistratose patches, ± pellucid, 8–12 μm wide in mid-leaf. Perichaetial leaves similar to upper vegetative leaves. Setae straight; capsules ovate-ellipsoid, smooth; exothecial cells quadrate to rectangular, thickwalled; lid rostellate; spores c. 14 μm. Capsules occasional, autumn. n = 13∗ . On moist sheltered or exposed acidic heavy-metal-bearing rocks on cliffs, in scree and by lakes. 200–900 m. Rare, N. W. Wales, Lake District, Dumfries, central Scottish Highlands north to W. Sutherland, W. Donegal. 16, H1. GB23 + 6∗ , IR1. Suboceanic Boreal-montane. Very rare in Europe, from Spain, Italy and Romania north to Norway and Sweden, temperate and tropical Asia, Labrador, Bolivia.

Subgenus 5 Rhabdogrimmia Limpr., Laubm. Deutschl., 1889 Leaf margins recurved; cells usually unistratose except at margins, usually pellucid. Setae long, arcuate when moist; capsules cernuous or pendulous, usually striate or ribbed. Section 1 Pulvinatae Bruch & Schimp., in Bruch et al., Bryol. Eur., 1845 Autoicous. Leaves abruptly narrowed at apex; costa in section semiterete, with small group of stereids; basal cells wide, quadrate or rectangular.

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Fig. 141 1–7, Grimmia pulvinata: 1, leaves; 2, costa section in lower part of leaf; 3, basal marginal cells; 4, basal cells next to costa; 5, mid-leaf cells; 6, 7, capsules. 8–13, G. orbicularis: 8, leaf; 9, costa section in lower part of leaf; 10, basal marginal cells; 11, basal cells next to costa; 12, mid-leaf cells; 13, capsule. Leaves ×15, sections ×280, lamina cells ×420, capsules ×15.

15 G. pulvinata (Hedw.) Sm., Engl. Bot., 1807 G. pulvinata var. africana (Hedw.) Hook. f. & Wilson

(Fig. 141)

Autoicous. Dense rounded grey-green cushions, hoary when dry, to 3 cm high. Leaves erect, appressed when dry, erect-patent when moist, upper lanceolate to ovate-lanceolate, keeled above, shortly tapering or abruptly narrowed into hyaline point; margins recurved on one or both sides, bistratose above, hyaline points 1/ –1(−2) length of lamina in upper leaves, smooth to slightly denticulate; costa 2 well defined, in section 2 cells wide adaxially; basal cells mostly shortly rectangular or rectangular, those next to costa with walls thin and straight to incrassate and nodulose, 2–4(−6) times as long as wide, basal marginal cells 1–4 times as long

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as wide, with transverse walls thicker than longitudinal, cells above quadrate to quadrate-rectangular, incrassate, sinuose, unistratose, pellucid, 7–10 μm wide in mid-leaf. Perigonia inconspicuous, immediately below perichaetia, outer perigonial bracts very different from vegetative leaves, filmy, orange, muticous, ecostate. Perichaetial leaves longer than vegetative leaves, bases sheathing. Setae flexuose when dry; arcuate when moist, burying capsules in points of perichaetial leaves; capsules ovate-ellipsoid or occasionally ovoid, ribbed; peristome teeth ± entire; lid rostrate or rostellate, conical when capsules ovoid; spores 8–12 μm; calyptrae mitriform. Capsules very common, spring. n = 13∗ , 26∗ , 26 + m∗ . On dry exposed usually basic rocks, especially characteristic of man-made habitats such as walls, old buildings and concrete, rarely on trees. 0–625 m. Very common except in the Scottish Highlands. 112, H40, C. GB1649 + 84∗ , IR246 + 8∗ , C6 + 1∗ . Circumpolar Southern-temperate. From most parts of the world except the Arctic and Antarctic. The commonest species of Grimmia in the British Isles and only likely to be confused with G. orbicularis. The latter differs in the larger, blacker, readily disintegrating less neat tufts, in the longer basal cells of the leaves (although in some non-British G. pulvinata these cells may be long), in the perigonia and in capsule shape. G. decipiens looks superficially like G. pulvinata, but forms larger laxer tufts and has longly tapering leaves with long narrow basal cells. The plant referred to as var. africana (Hedw.) Hook. f. & Wilson has ovoid capsules with shortly conical lids and may be mistaken for G. orbicularis. However, it is clear from the limited amount of material that I have seen that intermediates occur even in the same gathering and var. africana cannot be maintained.

16 G. orbicularis Bruch in Wilson, Eng. Bot. Suppl. 4, 1844 (Fig. 141) Autoicous. Lax readily disintegrating cushions, greenish black above, blackish below, hoary when dry, to c. 4 cm high. Leaves erect, appressed when dry, erect-patent when moist, upper lanceolate-elliptical to ovate-lanceolate, keeled above, abruptly narrowed to hyaline point; margins recurved on one or both sides at middle of leaf; hyaline points 1/2 –1(−2) length of lamina, smooth or slightly denticulate; costa well defined, in section 2 cells wide adaxially; basal cells narrowly rectangular to elongate, with thick longitudinal walls and thin transverse walls except near margins, cells near costa with incrassate nodulose longitudinal walls, (6−)8–10 times as long as wide, basal marginal cells 4–8 times as long as wide, transverse walls thicker than longitudinal walls, cells above quadrate or quadrate-rectangular, incrassate, sinuose, unistratose or bistratose in patches, pellucid, 10–12 μm wide in mid-leaf. Perigonia conspicuous, terminal on branches, outer perigonial bracts similar to stem leaves. Perichaetial leaves longer than vegetative leaves, with sheathing bases. Setae arcuate when moist, immersing capsules in perichaetial leaf points; capsules subglobose, striate; peristome teeth cribrose and cleft; lid mamillate, obtuse; calyptrae cucullate; spores 10–14 μm. On dry exposed basic rocks and walls, especially limestone, also on

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heavy-metal-bearing rocks. 0–365 m. Rare to occasional and decreasing, but sometimes locally common, from W. Cornwall and Devon east to W. Kent and north to Skye and W. Sutherland, old records from Mid and E. Cork, Dublin. 35, H3. GB41 + 51∗ , IR5∗ . Submediterranean-Subatlantic. Europe from the Mediterranean region north to the Netherlands, Germany and Poland, Caucasus, Turkey, Cyprus, Middle East, Pakistan, U.S.A., Mexico, New Zealand, Kerguelen Is. Section 2 Trichophyllae Bruch & Schimp., in Bruch et al., Bryol. Eur., 1845 Dioicous or autoicous. Leaves tapering to acuminate apex; costa in section semiterete or reniform, sometimes winged, with ± distinct group of stereids in section; basal cells narrow. 17 G. torquata Hornsch. ex Drumm., Musci Scot. Exsicc., 1825 (Fig. 142) Dioicous. Brownish often tumid tufts, 1–5 cm high. Leaves loosely spirally crisped when dry, erect-patent when moist, narrowly oblong-lanceolate, keeled above, acute; margins recurved on one or both sides; hyaline points short, to 250 μm long in upper leaves, very rarely longer, smooth; costa faint below, strong above, ending in or below apex, 2 cells wide on adaxial side in section; basal cells with very incrassate nodulose longitudinal walls and thin transverse walls except at margins, cells next to costa 6–9 times as long as wide, basal marginal cells 4–8 times as long as wide, transverse walls not thicker than longitudinal walls, 1–3 rows of cells at margins thin-walled, hyaline, cells above quadrate-rectangular to quadrate, very incrassate, sinuose, unistratose, pellucid, 8–10 μm wide in midleaf. Brown multicellular gemmae, 40–120 μm diameter, often present on abaxial side of upper leaves. Setae arcuate; capsules ovoid. Capsules unknown in the British Isles. On sheltered or exposed, usually slightly basic, periodically moist rock ledges and scree, rarely on coastal cliffs. 0–1050 m. Occasional in W. and N. Britain from Carmarthen and Brecon north to Sutherland, Kerry, Waterford, S. Tipperary, Wicklow, W. Mayo. 34, H6. GB135 + 33∗ , IR8 + 2∗ . European Boreoarctic Montane. Montane and northern Europe north to Svalbard, Faeroes, Iceland, Siberia, China, Madeira, La Palma, Tenerife, N. America, Greenland, Hawaii. ¨ 18 G. funalis (Schwagr.) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1845 (Fig. 142) Dioicous. Dense dark grey readily disintegrating tufts, (1−)2–4 cm high. Leaves spirally arranged, appressed, curved when dry, sometimes giving shoots string-like appearance, erect-patent when moist, ovate-lanceolate to narrowly lanceolate, keeled above; margins recurved; hyaline points thin, 1/2 –1 as long as lamina in upper leaves, slightly denticulate; costa faint below, strong above, ending in apex, 2 cells wide on adaxial side in section; basal cells with very incrassate nodulose longitudinal walls and thin transverse walls except near margins, those by costa 3–8(−10) times as long as wide, basal marginal cells (1−)3–6 times as long as wide, transverse walls thicker than longitudinal walls, 1–2 rows at margins elongate,

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Fig. 142 1–8, Grimmia funalis: 1, dry shoot; 2, leaves (×25); 3, costa section in lower part of leaf; 4, basal marginal cells; 5, basal cells next to costa; 6, mid-leaf cells; 7, capsule; 8, filiform shoot. 9–15, G. torquata: 9, dry shoot; 10, leaves (×35); 11, costa section in lower part of leaf; 12, basal marginal cells; 13, basal cells next to costa; 14, mid-leaf cells; 15, gemma (×15). 16–21, G. incurva: 16, leaves (×20); 17, costa section in lower part of leaf; 18, basal marginal cells; 19, basal cells next to costa; 20, mid-leaf cells; 21, capsule. Dry shoots ×10, sections ×280, lamina cells ×420, capsules ×15.

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hyaline, cells above quadrate-rectangular to quadrate, sinuose, unistratose, pellucid, 10 μm wide in mid-leaf. Caducous flagelliform shoots with minute concave leaves with bent costa and recurved apiculus often present. Setae arcuate when moist, concealing capsules in points of perichaetial leaves; capsules ovoid, striate; spores 16–18 μm. Capsules occasional, late summer. On ledges and in crevices of dry or periodically damp basic rocks, rock ledges and scree, rarely on sea-cliffs. (0−)300–1205 m. Occasional in N. W. Wales, N. W. England and the Scottish mountains, rare in W. Ireland, S. Tipperary, Dublin. 35, H11. GB116 + 43∗ , IR10 + 12∗ . European Boreal-montane. Europe north to c. 67◦ N, Faeroes, Iceland, Caucasus, Turkey, Himalayas, Altai, China, Japan, El Hierro, Tenerife, Algeria, Morocco, Lebanon, Labrador, Greenland. The neat dark grey tufts with the appressed curved leaves often giving the shoots a stringlike appearance when dry make this an easy species to recognise. When present the flagelliform shoots with appressed concave leaves are also very distinctive. G. trichophylla is a coarser plant of different aspect when dry.

¨ 19 G. incurva Schwagr., Sp. Musc. Frond. Suppl. 1, 1811. (Fig. 142) Dioicous. Dark green tufts or patches, blackish below, 1.0–2.5 cm high. Leaves crisped or rarely ± straight when dry, spreading from ± erect basal part when moist, narrowly linear-lanceolate to narrowly lanceolate or ligulate from narrowly ovate basal part, keeled above, acute; margins plane or slightly recurved; hyaline points absent in lower leaves, very short in upper, to 120 μm long; costa very strong, ending in or below apex; basal cells thin-walled, hyaline, those adjacent to costa 6–10 times as long as wide, basal marginal cells 6–10 times as long as wide, walls uniformly very thin, cells above quadrate, incrassate, sinuose, ± opaque, bistratose at margins and towards apex, 10–12 μm wide in mid-leaf. Setae arcuate when moist, burying capsules in perichaetial leaf points; capsules ovate-ellipsoid, smooth; spores c. 15 μm. Capsules very rare, spring. On exposed dry acidic rocks. especially on hill or mountain summits but also in boulder scree. 300–950 m. Rare, Shropshire, Caernarfon, N. Northumberland, Lake District, Kirkcudbright, E. Perth, Angus, Kincardine, S. Aberdeen, Banff, Argyll. 13. GB16 + 7∗ . European Boreo-arctic Montane. Montane Europe from Spain, Italy and Yugoslavia north to Svalbard, Iceland, Novaya Zemlya, Caucasus, Urals, Mongolia, China, Japan, Azores, N. America, Greenland, Mexico. A variable species, forms from exposed situations having shorter wider leaves less strongly crisped when dry. Such plants may superficially resemble an Andreaea in the field but differ in presence of short hair-points and in areolation. May also be mistaken for Dicranoweisia crispula, but that species has muticous leaves and different areolation.

20 G. trichophylla Grev., Fl. Edinensis, 1824 (Fig. 143) ¨ Hal., G. britannica A. J. E. Sm., G. stirtonii G. ausrtofunalis auct. non Mull. Schimp., G. trichophylla var. robusta (Fergusson) A. J. E. Sm. Dioicous. Yellowish green to blackish green lax readily disintegrating tufts or patches, hoary when dry; shoots to 3.5 cm long, with plants to 1 cm high. Leaves

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Fig. 143 Grimmia trichophylla: 1, moist leaves; 2, dry leaves; 3, costa section in lower part of leaf (×210); 4, basal marginal cells from different plants; 5, basal cells next to costa from different plants; 6, mid-leaf cells; 7, capsule (×15); 8, gemmae (×420). Leaves ×20, lamina cells ×420.

appressed-flexuose to slightly twisted, folded longitudinally above when dry, erect to spreading, rarely squarrose when moist, lanceolate to narrowly lanceolate, keeled above, tapering to acute apex, narrowed or not at insertion; margins recurved on one or both sides below; hyaline points to 3/4 length of lamina in upper leaves, smooth to denticulate; costa in section semicircular, 2 cells wide on adaxial side, with 2 layers of guide cells at extreme base, abaxial layer 4 cells wide; basal cells near costa 2–6 times as long as wide, thin-walled and straight to thick-walled and nodulose, basal marginal cells 2–4 times as long as wide, transverse walls thicker than longitudinal walls, cells above quadrate, incrassate, usually sinuose, 1–2-stratose, pellucid, bistratose at margins, 8–10 μm wide in mid-leaf. Irregularly shaped gemmae, to c. 60 μm diameter sometimes present on abaxial surface

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of leaves. Setae flexuose when dry, arcuate when moist, burying capsules in tips of perichaetial leaves; capsules ovoid to obloid, ribbed, abruptly narrowed into seta; peristome teeth papillose, split; spores 10–14 μm. Capsules rare, spring. n = 13, 26. On exposed cliffs, rock outcrops, sarsen stones, tombstones, glacial erratics, boulders, roofs, walls, where acidic, calcifuge. 0–990 m. Very rare in lowland England and lowland Ireland, frequent to common elsewhere. 96 H28, C. GB641 + 92∗ , IR63 + 16∗ , C6 + 1∗ . Circumpolar Wide-temperate. Europe to c. 65◦ N, Faeroes, Caucasus, Turkey, Cyprus, Siberia, Macaronesia, Morocco, Algeria, N. and C. America, Andes from Venezuela to Tierra del Fuego, Australasia, Hawaii. G. trichophylla is the commonest Grimmia of acidic rocks and is usually easily recognised by the readily disintegrating tufts or patches, which are hoary when dry. Most frequently confused with members of the Schistidium apocarpum agg. which, however, have relatively shorter wider leaves, different leaf areolation and immersed capsules, and usually occur on basic substrates. A number of varieties have been described from the British Isles. Some of these are based upon leaf areolation, but this is a feature very much influenced by environmental conditions ˜ (J. Munoz, pers. commun.). These include var. stirtonii and var. robusta (G. britannica). On the other hand, var. tenuis (Wahlenb.) Wijk & Margad. and var. subsquarrosa (Wilson) A. J. E. Sm. have been shown to be species in their own right, i.e. G. muehlenbeckii Schimp., which does not occur in the British Isles, and G. lisae De Not. The former differs from G. trichophylla in the costa being ribbed on the abaxial side. For the differences from G. lisae see under that species. I concluded that var. robusta should be treated as a species and named it G. britannica. Later, H. G. Greven (J. Bryol. 19, 927–830, 1997) said that G. britannica was synonymous ¨ Hal. However, all British and Irish with the Southern Hemisphere G. austrofunalis Mull. ˜ specimens named G. britannica/G. austrofunalis examined by J. Munoz (pers. commun.) belong either to G. trichophylla or G. longirostris, and G. austrofunalis (which is very distinct from G. trichophylla) does not occur in the Northern Hemisphere. In G. trichophylla, gemma development leads to degeneration of the cells producing them ˜ and the ultimate destruction of the leaf. For a detailed account of this see J. Munoz, Ann. Missouri Bot. Gard. 86, 118–91, 1999.

Section 3 Hartmaniae 21 G. dissimulata E. Maier, Candollea, 2002 Dioicous. Lax readily disintegrating greenish tufts, hoary when dry, shoots to c. 2 cm long. Leaves loosely appressed to imbricate, ± straight and flat when dry, patent to spreading when moist, lanceolate, tapering to acute apex, channelled above, margins recurved below; hyaline points to 1/2 length of lamina in upper leaves, slightly denticulate; costa in section 4 cells wide on adaxial side, with single layer of 4 guide cells at extreme base; basal cells near costa 4–6 times as long as wide, basal marginal cells 2–4 times as long as wide, transverse walls thicker than longitudinal walls, other basal cells nodulose, cells above quadrate to rounded-quadrate, sinuose, bistratose at margins, 8–10 μm wide in mid-leaf. Setae flexuose when dry, arcuate when moist; capsules ovoid, ribbed; rare, spring.

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On limestone walls, tombstones and rocks, calcicole. Distribution and frequency uncertain but apparently frequent in east Anglia, rare elsewhere, N. Hampshire, Derby, E. Ross. 7. Europe. It is likely that specimens from limestone or similarly basic rocks named G. trichophylla belong to this species. It resembles G. lisae macroscopically when dry with appressed, ± straight and flat leaves and in the costa four cells wide on the adaxial side. It differs in the costa having 4 instead of 6 guide cells at the extreme base and in being markedly calcicolous. There are said to be differences from G. trichophylla in the shape of the basal marginal cells and G. dissimulata has nodulose basal cell walls. However, some forms of G. trichophylla have nodulose basal cells and length of basal marginal cells is very variable so basal areolation is an unreliable character. The nature of costa section is the best character for differentiation. For the occurrence of G. dissimulata in Britian see R. D. Porley, Field Bryology 82, 13–17, 2004.

22 G. lisae De Not., Musc. Ital. Spic., 1837 (Fig. 144) G. retract Stirt., G. subsquarrosa Wilson, G. trichophylla var. subsquarrosa (Wilson) A. J. E. Sm. Dioicous. Greenish black sometimes silt-encrusted lax or tight tufts or patches, to 3.5 cm high. Leaves loosely appressed to imbricate, straight, ± flat above when dry, usually recurved to squarrose when moist, lanceolate or ovate-lanceolate, tapering to acute apex, channelled above; margins recurved below; hyaline points to 3/4 length of lamina in upper leaves, slightly denticulate; costa in section 4 cells wide on adaxial side, with single layer of 6 guide cells at extreme base; basal cells thickened, esinuose or slightly sinuose, near costa 2–6 times as long as wide, basal marginal cells 1–3 times as long as wide, transverse walls thickened, cells above quadrate to wider than long, incrassate or not, esinuose, unistratose with bistratose patches, pellucid, 8–10 μm wide in mid-leaf. Gemmae lacking in British and Irish material. Setae arcuate when moist; capsules ellipsoid, weakly ribbed, unknown in the British Isles. On acidic rocks, often near water, in sheltered situations such as ravines and woods, also in exposed sites, often below flood level by rivers, streams and lakes. 0–600 m. Occasional in western and northern Britain, and a few localities in Ireland. Distribution data require revision. Mediterranean-Atlantic. S. and W. Europe, Cyprus, Macaronesia, western N. America, Mexico. G. lisae differs from G. trichophylla in the leaves usually squarrose when moist and ± straight and flat above (i.e. not longitudinally folded when dry) and the costa 4 cells wide on the adaxial side in section. It differs from G. hartmanii in the squarrose rather than secund leaves, the usually longer hyaline points and the thinner-walled esinuose or slightly sinuose basal cells. The type specimens of G. retracta Stirt. and G. subsquarrosa Wilson belong to G. lisae. Most British and Irish specimens so named that I have examined are G. lisae, although a few are G. trichophylla. A number of gatherings labelled ‘subsquarrosa’ belong to G. trichophylla and the distribution of G. lisae in the British Isles requires revision.

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Fig. 144 1–6, Grimmia lisae: 1, moist leaves; 2, dry leaves; 3, costa section in lower part of leaf; 4, basal marginal cells; 5, basal cells next to costa; 6, mid-leaf cells. 7–12, G. hartmanii: 7, leaves; 8, costa section in lower part of leaf; 9, basal marginal cells; 10, basal cells next to costa; 11, mid-leaf cells; 12, gemmae (×125). Leaves ×15, sections ×280, lamina cells ×420.

23 G. hartmanii Schimp., Syn. Musc. Eur., 1860 (Fig. 144) Dioicous. Yellowish green to green tufts or patches (0.5−)1.0–4.0(−6.0) cm high. Leaves slightly contorted and often with tips secund when dry, patent or recurved and frequently secund when moist, lanceolate, keeled above, tapering to acute apex; margins recurved on one or both sides below; hyaline points 40–320(−500) μm long in upper leaves, rarely longer, denticulate; costa 4 cells wide on adaxial side in section; basal cells incrassate, slightly to strongly sinuose, cells next to costa 2–5 times as long as wide, basal marginal cells 1–2 times

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as long as wide, transverse walls strongly thickened, cells above quadrate, incrassate, usually sinuose, unistratose except at margins, pellucid, 8–10 μm wide in mid-leaf. Clusters of brownish mulberry-shaped gemmae, c. 250 μm diameter, usually present on the tips of progressively deformed leaves at shoot apices. Setae arcuate; capsules ovoid, smooth, unknown in the British Isles. On periodically moist basic or acidic rock, rarely on tree trunks, usually by water, in woods and ravines, on exposed rocks by lakes. 0–915 m. Occasional to frequent and sometimes locally abundant in western and northern Britain, from E. Cornwall, S. Devon, W. Gloucester and Wales north to Sutherland, rare in Ireland. 47, H13. GB161 + 51∗ , IR5 + 12∗ . European Boreal-montane. From Mediterranean Europe to c. 69◦ N, Caucasus, Turkey, Siberia, Japan, N. Africa, N. America. Usually distinguished by the secund leaves and presence of gemmae at the shoot tips. In humid woodland G. hartmanii may form a short turf and gemmae may be absent. Plants with long hyaline points do occur and I have seen gatherings with the hyaline points as long as the lamina, but such plants are exceedingly rare.

24 G. decipiens (Schultz) Lindb. in Hartm., Scand. Fl., 1861 (Fig. 145) Autoicous. Lax readily disintegrating tufts or cushions, blackish below, hoary when dry, 1.0–2.5(−4.0) cm high. Leaves loosely appressed when dry, erectpatent when moist, lanceolate to broadly lanceolate, tapering to acute apex, keeled above, both margins recurved; hyaline points to as long as lamina in upper leaves, decurrent down margins, strongly denticulate; costa ending in apex, 4–6 cells wide on adaxial side in section; basal cells elongate, incrassate, esinuose or slightly sinuose, those next to costa 4–8 times as long as wide, basal marginal cells hyaline, 1–4 times as long as wide, with thickened transverse walls, forming conspicuous marginal band, cells above rectangular to quadrate, incrassate, very sinuose, unistratose except at margins, pellucid, 7–10 μm wide in mid-leaf. Setae arcuate when moist, immersing capsules in tips of perichaetial leaves; capsules ellipsoid, abruptly narrowed into seta, striate; peristome teeth papillose, split; spores 12– 14 μm. Capsules common. n = 13. On often sloping exposed or slightly shaded calcareous or more rarely acidic rocks and walls. Lowland. Rare and decreasing, widely distributed from Cornwall east to Sussex and north to Sutherland and Caithness, very rare in Ireland, Guernsey, Jersey. 48, H8, C. GB23 + 43∗ , IR2 + 9∗ , C1 + 1∗ . Submediterranean-Subatlantic. Mediterranean Europe and the Crimea to c. 67◦ N, Cyprus, Turkey, Armenia, Madeira, Canary Islands, Algeria, Morocco, Canada, Alaska. This species has probably suffered from over-collecting because of the conspicuous nature of the tufts. It is like coarse G. pulvinata, but differs in leaf shape and areolation. From G. trichophylla it differs in habitat, habit, leaf areolation and costa section.

Section 4 Elatiores With the characters of the species.

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Fig. 145 1–6, Grimmia decipiens: 1, leaves (×15); 2, costa section in lower part of leaf; 3, basal marginal cells; 4, basal cells next to costa; 5, mid-leaf cells; 6, capsule. 7–11, G. elatior: 7, leaves (×15); 8, costa section in lower part of leaf; 9, basal marginal cells; 10, basal cells next to costa; 11, mid-leaf cells. 12–17, G. ramondii: 12, leaves (×20); 13, costa section in lower part of leaf; 14, basal marginal cells; 15, basal cells next to costa; 16, mid-leaf cells; 17, old capsule. Sections ×280, lamina cells ×420, capsules ×15.

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25 G. elatior Bruch ex Bals.-Criv. & De Not., Mem. Reale Acad. Sci. Torino, 1838 (Fig. 145) Dioicous. Dark green to brownish readily disintegrating tufts or patches, shoots to 7 cm long. Leaves loosely appressed when dry, erect-patent to spreading when moist, narrowly lanceolate from broad base, keeled above; margins strongly recurved on one side, less so or plane on the other; hyaline points to 1/2 length of lamina in upper leaves, smooth to slightly denticulate; costa ending in apex, 2 cells wide on adaxial side in section; longitudinal walls of basal cells strongly incrassate, nodulose, transverse walls thin except towards margins, cells adjacent to costa (1−)2–3 times as long as wide, basal marginal cells 1–2 times as long as wide, with ± thickened transverse walls, marginal row longer, cells above irregularly quadrate to rounded-hexagonal, incrassate, very sinuose, strongly papillose, 2–3-stratose, opaque, 8–10 μm wide in mid-leaf. Setae arcuate when moist; capsules ellipsoid, striate; spores c. 15 μm. Capsules not known in Scotland. In large masses in Glen Clova, Angus, but not seen since 1871, also recorded from an unknown site in S. Aberdeen. 2. GB1∗ . Circumpolar Boreal-montane. Montane Europe north to Svalbard, Caucasus, Turkey, Urals, Siberia, India, Altai, China, Taiwan, Japan, N. America, Greenland. Hardly likely to be mistaken for any other species of British Grimmia because of its large size and opaque strongly papillose cells. There are large gatherings in various herbaria and the species has probably been lost because of over-collecting.

Subgenus 6 Dryptodon (Brid.) Lindb., Musci Scand., 1879 With the characters of the species. 26 G. ramondii (Lam. & DC.) Margad., Lindbergia, 1972 (Fig. 145) Dryptodon patens (Dicks. ex Hedw.) Brid., G. curvata (Brid.) De Sloover, G. patens (Dicks. ex Hedw.) Bruch & Schimp., Racomitrium patens (Dicks. ex Hedw.) Huebener Dioicous. Lax green or yellowish green to brownish patches, blackish below, stems (1−)2–10 cm long, procumbent to erect, often curved. Leaves loosely appressed when dry, patent, often subsecund when moist, lanceolate, tapering to acute to subobtuse entire or slightly toothed apex, keeled above; hyaline points lacking; margins recurved on one or both sides; hyaline points absent; costa stout, prominently two-winged on abaxial side above, in section 4 or 6 cells wide on adaxial side; basal cells linear, walls strongly incrassate, nodulose, cells next to costa 3–5 times as long as wide, basal marginal cells 1–2 times as long as wide, transverse walls of marginal 1–2 rows thicker than longitudinal walls, cells above irregularly quadrate or quadrate-rectangular, strongly incrassate and sinuose, unistratose except at margins, pellucid, 8–12 μm wide in mid-leaf. Setae yellow, arcuate at maturity, flexuose with age; capsules ellipsoid, ribbed, plicate when dry and empty; spores 12–16 μm. Capsules rare, spring. n = 22. On acidic to slightly basic moist

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sheltered or exposed rocks by water and on intermittently flushed rock outcrops and cliffs. 0–1000 m. Rare to occasional in N. W. Wales, N. W. England and the Scottish Highlands north to Shetland, very rare elsewhere, E. Cornwall, S. Devon, Carmarthen, Derby, rare in Ireland. 37, H14. GB140 + 44∗ , IR12 + 4∗ . European Boreal-montane. Montane Europe north to c. 69◦ N, Iceland, Faeroes, Siberia, Altai, Japan, Madeira, Tenerife, N. America, Greenland. Only likely to be mistaken in the field for Racomitrium aquaticum (q.v.). Variously placed in Grimmia, Dryptodon Brid. and Racomitrium, but all the sporophyte characters are found in at least some of the species of Grimmia subgenus Rhabdogrimmia and the best place for the species seems to be in the genus Grimmia (Greven, 1995).

79 RACOMITRIUM BRID., MUSCOL. RECENT. SUPPL., 1819 RHACOMITRIUM AUCT. NON BRID. Dioicous. Cladocarpous, stems erect to prostrate, often elongate and frequently with numerous short branches. Leaves lingulate to narrowly lanceolate, with or without hyaline apex; margins plane or recurved, usually entire; costa ending in apex; basal cells linear, sinuose-nodulose, alar cells differentiated or not, other cells sinuose, incrassate, quadrate to narrowly rectangular, sometimes bistratose at margins and/or above, smooth or papillose. Antheridia and archegonia on short lateral branches. Setae usually straight; capsules ellipsoid to cylindrical, smooth; peristome teeth perforated or divided nearly to base into 2–3 filiform papillose segments; calyptrae mitriform, not plicate. A cosmopolitan genus of about 80 mainly saxicolous species. Derivation: Meaning fringed cap, referring to the calyptrae. Recent revisions of the R. heterostichum agg., species 5–8 (A. A. Frisvoll, Gunneria 59, 1–289, 1988) and the R. canescens agg., species 11–13 (A. A. Frisvoll, Gunneria 41, 1–191, 1983), have resolved some long-standing problems in the taxonomy of the species concerned and have resulted in an increase by four in the number of species recognised in the British Isles.

1 Leaves with coarsely and irregularly toothed hyaline points 10. R. lanuginosum Hyaline points if present entire or denticulate but never coarsely and irregularly toothed 2 2 Leaf cells smooth or slightly papillose, hyaline points if present entire or denticulate, not papillose 3 Leaf cells strongly papillose, hyaline points if present papillose at least towards base, ± denticulate 12 3 Leaves without hyaline points 4 At least uppermost leaves with hyaline points 8

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4 Leaf apices rounded, often toothed 7. R. aciculare Apices acuminate to obtuse, entire 5 5 Cells in upper part of leaf narrowly rectangular to linear, costa weak, poorly defined above, stems with numerous short branches 9. R. fasciculare Upper cells quadrate to rectangular, costa strong, short branches present or not 6 6 Cells in upper part of leaves bistratose, opaque, costa constituting most of upper part of leaf 1. R. ellipticum Cells in upper part of leaves unistratose except sometimes at margins, pellucid, costa not filling leaf apex 7 7 Leaf apices obtuse; margins narrowly recurved below, plane above, cells weakly papillose 8. R. aquaticum Leaf apices acuminate to obtuse; margins recurved ± to apex, cells smooth 8 8 Cells in upper part of leaf narrowly rectangular, 3–4 times as long as wide, apex of innermost perichaetial leaves somewhat reflexed 6. R. himalayanum Upper cells quadrate to rectangular, not more than twice as long as wide, perichaetial leaf tips not reflexed 9 9 Plants often but not always dark grey to blackish and hoary when dry, costa in section bistratose except near base, 4–8 cells wide on adaxial side in middle part of leaf, hyaline points if present often decurrent down margins, capsules cylindrical 5. R. heterostichum Plants not grey to blackish and hoary when dry, costa 3–4-stratose except towards apex, c. 4 cells wide on adaxial side in middle part of leaf, hyaline points rarely decurrent down margins, capsules ellipsoid or cylindrical 10 10 Leaf apices not attenuate, hyaline points if present flattened towards base, costa in section ± flat on adaxial side in lower par of leaf, capsules cylindrical, leaves usually lying flat when mounted on a slide 4. R. affine Leaf apices attenuate, hyaline points if present not flattened, costa channelled in lower part, capsules ellipsoid, leaves rarely lying flat on a slide 11 11 Marginal 2–4 rows of cells in upper part of leaves bistratose, moderately robust usually reddish brown plants 2. R. macounii Marginal cells unistratose or only one row bistratose, slender to moderately robust dull green to brownish plants 3. R. sudeticum 12 Marginal row of hyaline non-sinuose supra-alar cells (i.e. cells immediately above enlarged alar cells) quadrate 12. R. elongatum Supra-alar cells rectangular 13 13 Leaves strongly keeled above, costa extending to apex, papillae on abaxial side of leaf near costa about 1/3 from base 0.5–1.0 times as tall as wide 11. R. ericoides Leaves weakly keeled above, costa extending 1/2 –3/4 way up leaf, abaxial papillae 1–2 times as tall as wide 13. R. canescens

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Section 1 Laevifolia (Kindb.) Nog., J. Hattori Bot. Lab., 1974 Leaves lanceolate, usually with denticulate hyaline points; alar cells slightly differentiated, row of esinuose hyaline basal marginal cells usually present, cells above not papillose. Setae smooth, twisted anticlockwise when dry. 1 R. ellipticum (Turner) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1845 (Fig. 146) Dark green to brownish or rarely reddish brown tufts, not hoary when dry, 0.5–2.0 cm high. Shoots erect; stems reddish, branched. Leaves ± straight, closely appressed when dry, spreading when moist, lanceolate from broad base, subobtuse; hyaline points lacking; margins plane or recurved on one or both sides below; costa broad, constituting much of apex; cells smooth, incrassate, basal ± linear, sinuose-nodulose, shorter towards margins, basal marginal cells hyaline, cells above sinuose, in mid-leaf rectangular, 8–10 μm wide, above irregularly quadrate, opaque, bistratose. Setae straight or slightly curved; capsules broadly ovoid; lid longly rostrate; peristome teeth divided into 2–3 filiform segments; spores 18–20 μm. Capsules common, early summer. n = 13∗ . On damp or periodically flushed acidic or mildly basic usually shaded rocks and rock ledges. 0–800 m. Occasional to frequent in N. W. Wales, the Lake District and N. W. Scotland, occasional in N. and W. Ireland. 28, H13. GB141 + 25∗ , IR29 + 13∗ . Oceanic Boreal-montane. Faeroes, Norway, Iceland, Tenerife, Japan (?). More likely to be confused in the field with Ulota hutchinsiae than with other species of Racomitrium except R. macounii (q.v.). The Ulota differs in the leaf cells unistratose, not sinuose, the ribbed ovate-ellipsoid capsules becoming ± cylindrical when dry and empty and in the hairy calyptrae.

2 R. macounii Kindb. ssp. alpinum (E. Lawton) Frisvoll, Gunneria, 1988 (Fig. 147) Reddish green to reddish brown tufts or patches, never hoary when dry. Shoots moderately robust, 3.5–5.5 cm long; stems simple or sparsely branched. Leaves appressed, straight when dry, erect-patent to spreading when moist, upper 2–3 mm long including hyaline point if present, narrowly lanceolate, tapering to attenuate apex; uppermost leaves mostly with at least some trace of hyaline or more usually reddish points, often reflexed when dry, 0–200 μm long, constituting 0.0–5.0(−7.5)% total leaf length, not flattened at base nor decurrent down margins; margins plane to strongly recurved on one side; costa in section channelled on adaxial side, strongly convex on abaxial side, 3–4-stratose near base, 3–4-stratose and c. 4 cells wide on adaxial side at middle of leaf; cells smooth, incrassate, basal elongate, sinuose-nodulose, row of 0–20 basal marginal cells hyaline, esinuose, cells above sinuose, in mid-leaf quadrate-rectangular, 6–8 μm wide, 2–4 marginal rows bistratose in upper part of leaf. Perichaetial leaves hardly differentiated from stem leaves. Setae 2.8–3.6 mm long; capsules ellipsoid to narrowly ellipsoid, 1.00–1.72 mm long; spores 12–14 μm. Capsules very rare, early

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Fig. 146 1–6, Racomitrium ellipticum: 1, leaves (×30); 2, leaf apex; 3, section of upper part of leaf (×28); 4, basal cells; 5, cells from upper part of leaf; 6, capsule. 7–11, R. aquaticum: 7, leaf (×15); 8, leaf apex; 9, basal cells; 10, upper cells; 11, capsule. 12–16, R. aciculare: 12, leaves (×15); 13, leaf apex; 14, basal cells; 15, upper cells; 16, capsule. Apices ×115, cells ×420, capsules ×15.

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Fig. 147 1–6, Racomitrium macounii ssp. alpinum: 1, leaves; 2, leaf sections; 3, basal cells; 4, mid-leaf cells; 5, perichaetial leaf; 6, capsule. 7–12, R. sudeticum: 7, leaves; 8, leaf sections; 9, basal cells; 10; mid-leaf cells; 11, perichaetial leaf; 12, capsule. Leaves ×15, sections (a, near base, b, near middle, c, near apex) all ×200, cells ×420, capsules ×15.

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summer. On ± acidic rocks by streams and on flushed rocks in montane habitats. 40–1160 m. Very rare, Carmarthen, Merioneth, Caernarfon, Westmorland, Mid-Perth, Angus, S. Aberdeen, Banff, Inverness, Argyll, Ross, W. Sutherland, S. Kerry. 14, H1. GB13 + 1∗ , IR1. European Boreal-montane. Widespread but rare in Europe north to Svalbard, Faeroes, Iceland, Caucasus, Turkey, Japan, north-west N. America, Greenland. This is the plant referred to as R. heterostichum var. alopecurum by Dixon & Jameson (1924) and is not to be confused with genuine var. alopecurum (i.e. R. affine). It differs from robust forms of R. ellipticum in that the leaves have attenuate apices and the uppermost usually have short reddish points; also in R. ellipticum the cells in the upper part of the leaf are bistratose and opaque. R. macounii differs from other members of the R. heterostichum complex in the usually reddish brown colour of the plants and the leaves with 2–4 marginal rows of cells bistratose in the upper part.

3 R. sudeticum (Funck) Bruch & Schimp. in Bruch et al., Bryol. Eur., 1845 (Fig. 147) R. affine auct. angl. Dull green to brownish, blackish or occasionally reddish brown cushions, tufts or mats, not hoary when dry. Shoots slender to robust, procumbent to erect, to 4–5 cm long, Stems simple or sparsely branched. Leaves loosely appressed, straight or slightly curved when dry, erect-patent to patent, subsecund when moist, 1.6–2.7(−3.0) mm long including hyaline points if present, narrowly lanceolate, tapering to acuminate apex; hyaline points usually short or absent, 0.0–0.2(−0.4) mm long, 0–10(−20)% total leaf length, rigid, denticulate or not, not flattened at base, not decurrent down margins; margins usually broadly recurved on one side, narrowly so on the other; costa in section channelled on adaxial side, strongly convex on abaxial side, 3–4-stratose except near apex, c. 4 cells wide on adaxial side at middle of leaf; cells smooth, incrassate, basal cells narrowly rectangular, sinuose-nodulose, row of 0–10(−15) basal marginal cells hyaline, esinuose, other cells sinuose, in mid-leaf rectangular or shortly rectangular, 8–10 μm wide, upper cells irregularly quadrate-rectangular, unistratose throughout or single marginal row bistratose. Inner perichaetial leaves differing slightly in shape from stem leaves, basal part hyaline; hyaline points slightly longer than in stem leaves. Setae 2.5–4.0 mm long, straight or curved; capsules ellipsoid, 0.8–1.4 mm long excluding rostrate lid; spores 12–16 μm. Capsules frequent, spring to autumn. n = 13 + m∗ , 14. On exposed acidic rocks, cliff ledges, walls, usually at high altitudes, occasionally on soil. 0–1344 m. Frequent or common in montane parts of the British Isles but under-recorded. 50, H15. GB46 + 5∗ , IR11 + 2∗ . Circumpolar Boreo-arctic Montane. Montane and arctic Europe north to Svalbard, Faeroes, Iceland, Turkey, Japan, N. America, Greenland. Likely to be confused with R. affine and non-hoary forms of R. heterostichum. A useful feature is that when mounted on a slide the leaves of R. sudeticum usually lie sideways whereas those

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of the next two species mostly lie flat. The leaves of R. sudeticum are relatively narrower with attenuate apices, the hyaline points where present are rigid and not flattened at the base. In R. affine, the costa in section near the leaf base is flat on the adaxial side whilst that of R. sudeticum is concave. In section, the costa of R. heterostichum, unlike that of R. sudeticum, is usually bistratose throughout except at the extreme base.

4 R. affine (Schleich. ex F. Weber & D. Mohr) Lindb., Acta Soc. Sci. Fenn., 1875 (Fig. 148) R. heterostichum var. alopecurum Huebener, R. heterostichum var. gracilescens Bruch & Schimp. Dull green to blackish or yellowish green tufts or patches, rarely hoary when dry. Shoots slender to medium-sized, to c. 5 cm long. Shoots erect to decumbent; stems sparsely to much branched. Leaves loosely appressed, straight or curved when dry, erect-patent to patent, sometimes subsecund when moist, lanceolate, (1.7−)2.0– 3.2(−3.6) mm long including hyaline points; hyaline points (0.0−)0.1–1.1 mm long, (0−)5–35% total leaf length, flexuose, denticulate, flattened at base, sometimes decurrent down margins; margins recurved on one side, plane or narrowly recurved on the other; costa in section flat on adaxial side near base, convex on abaxial side, 3−4-stratose and 4 cells wide on adaxial side near middle of leaf; cells smooth, incrassate, basal cells narrowly rectangular, sinuose-nodulose, row of 0–7 basal marginal cells hyaline, esinuose, other cells sinuose, in mid-leaf rectangular or shortly rectangular, 8–10 μm wide, upper cells shortly rectangular or irregularly quadrate, marginal row of cells unistratose or partially bistratose. Innermost perichaetial leaves differing markedly from stem leaves, smaller, hyaline, bluntly pointed, without hyaline points. Setae straight, 5–9 mm long; capsules shortly cylindrical, 2.0–2.4 mm long excluding rostrate lid; spores 12–20 μm. Capsules occasional, spring. On moist or dry acidic rocks, walls, roofs, tombstones. Mainly at low altitudes. Very rare in lowland England, occasional to frequent elsewhere, apparently rare in Ireland. 50, H6. GB36 + 21∗ , IR3 + 1∗ , but underrecorded. European Temperate. Europe north to Svalbard, Faeroes, Iceland, Jan Mayen, Turkey, Cyprus, Asia, N. Africa, Macaronesia, N. America. Often similar in appearance to R. sudeticum (q.v.) and in the past sometimes regarded as synonymous with it, but shown by A. A. Frisvoll (loc. cit.) to be distinct. Closely related to R. heterostichum (q.v.) and as intermediates occur it might perhaps be better treated as a variety of that species, i.e. var. alopecurum Huebener.

5 R. heterostichum (Hedw.) Brid., Muscol. Recent. Suppl., 1819 R. obtusum (Brid.) Brid.

(Fig. 148)

Dull green, brownish or blackish tufts or patches, often hoary when dry. Shoots slender to medium-sized, to 5 cm long; stems prostrate to ascending, sparsely to much branched, often with dwarf branches. Leaves loosely appressed, curved or

464

19 Grimmiaceae

Fig. 148 1–6, Racomitrium heterostichum: 1, leaves; 2, leaf sections; 3, basal cells; 4, mid-leaf cells; 5, perichaetial leaf; 6, capsule. 7–12, R. affine: 7, leaves; 8, leaf sections; 9, basal cells; 10, mid-leaf cells; 11, perichaetial leaf; 12, capsule. Leaves ×15, sections (a, near base, b, near middle, c, near apex) all ×200, cells ×420, capsules ×15.

79 Racomitrium

465

twisted when dry, erect-patent to patent when moist, mostly 2.0–3.5 mm long including hyaline points, lanceolate or more rarely narrowly lanceolate; hyaline points rarely absent, (0.0−)0.2–1.2(−1.4) mm long, (0−)10–35(−40)% total leaf length, flexuose and sometimes crinkled, flattened at base and often decurrent down margins; margins recurved on one side, sometimes strongly so, plane or less recurved on the other; costa in section somewhat channelled on adaxial side near base, weakly convex on abaxial side, mostly bistratose throughout except near base, 4–8 cells wide on adaxial side near middle of leaf; cells smooth, incrassate, basal narrowly rectangular, sinuose-nodulose, row of 0–8 basal marginal cells hyaline, esinuose, cells above sinuose, in mid-leaf rectangular or shortly rectangular, 8–10 μm wide, upper cells shortly rectangular or irregularly quadrate, marginal row of cells unistratose or partially bistratose. Innermost perichaetial leaves differing markedly from stem leaves, smaller, hyaline below, bluntly pointed, without hyaline points. Setae straight, 4.8–9.0 mm long; capsules ± shortly cylindrical, (1.5−)1.8–2.6 mm long excluding longly rostrate lid; spores 10–18 μm. Capsules occasional, spring. n = 13∗ , 14. On dry exposed or shaded acidic rocks, boulders, cliffs, walls, roofs, tombstones, sarsen stones. 0–400 m. Rare in lowland England, common elsewhere at lower altitudes. 85, H24. CB84 + 54∗ , IR21 + 3∗ . Suboceanic Boreo-temperate. W. Europe to 70◦ N, rare in E. Europe, Iceland, Macaronesia, western N. America. Although A. A. Frisvoll (loc. cit.) treats R. obtusum (Brid.) Brid. as a distinct species, and indeed in its extreme form it is very distinctive, in the British Isles it intergrades to such an extent with R. heterostichum that it cannot be recognised as taxonomically distinct even at the varietal rank. Usually distinct from R. sudeticum in leaf shape, the hyaline points flattened towards the base and decurrent down the margins, but small green shade forms may have narrowly lanceolate leaves with short hyaline points and it is necessary to cut sections of the costa to identify them. R. affine resembles slender forms of R. heterostichum, but may usually be distinguished by the costa in the middle of the leaf 3–4 cells thick and 4 cells wide on the adaxial side in section.

6 R. himalayanum (Mitt.) A. Jaeger, Ber. Thatigk. St. Gallishen Naturwiss. Ges., 1874