Annual General Meeting 2000: University of Reading

HomeEventsAnnual General Meeting 2000: University of Reading

8 September 2000 - 10 September 2000

Meeting report

Bryological symposium

Dr Jeff Bates (Imperial College, Ascot): Introduction to the Azores and its bryophytes

The speaker’s experience of the Azores is based upon three visits to Terceira, the third largest of the nine islands in the mid-Atlantic archipelago. The islands are volcanic in origin and relatively young, varying from less than 1 million years (Pico) to about 8 million years (Santa Maria) in age. The larger islands are mountainous and attract constant cap clouds around their peaks. Botanically, they have two attractions: a strong element of endemic species and highly oceanic conditions. Earlier work by Dr Sérgio has shown affinities of the bryophyte flora with various regions, including Europe (especially the Mediterranean), Africa and North America, but also the southern Hemisphere, notably in the genus Echinodium (Australasia) and South American species, such as Jamesoniella rubricaulis. A number of the special Azorean taxa are shared with other Atlantic islands in the Macaronesian group (e.g. Andoa berthelotiana, Tetrastichium virens). The strongly oceanic environment is reflected in the abundance of Plagiochila killarniensis (P. bifaria), Myurium hochstetteri, Hypnum uncinulatum, Cyclodictyon laetevirens, Dicranum scottianum, Leptoscyphus cuneifolius, several Lejeunea spp, and the ferns Hymenophyllum tunbrigense and Trichomanes speciosum. The high endemism is at odds with the young geological ages of the islands, and it is likely that Azorean endemics (e.g. Bazzania azorica, Cheilolejeunea cedercreutzii, Herbertus azoricus, Leptoscyphus azoricus, Tylimanthus azoricus, Echinodium renauldii), and perhaps other Macaronesian endemics (e.g. Aphanolejeunea madeirensis, Heteroscyphus denticulatus, Alophosia azorica, Echinodium prolixum) were formerly more widespread, but eliminated from less favourable sites during the Pleistocene glaciations.

The archipelago shows a gradient of increasing precipitation from east to west. On the larger islands precipitation increases with altitude and is largely responsible for a marked altitudinal zonation of the vegetation. The coastal strip is warm and dry with a sub-tropical climate. This zone now supports most of the human population. Formerly, the tree heather Erica scoparia subsp. azorica was dominant here together with native woody species, such as Myrica faya, but the Australian tree Pittosporum undulatum was introduced and has naturalised everywhere at lower altitudes. Common Mediterranean bryophytes, such as Philonotis rigida, Anthoceros punctatus, Gongylanthus ericetorum and Targionia hypophylla, are frequent on banks along rides in coastal Pittosporum woodland. Above 500 m the climate deteriorates significantly and the native evergreen forest is dominated by Laurus azorica and Juniperus brevifolia. In the constantly humid interior of this virtually impenetrable growth are found most of the characteristic Azorean bryophytes, covering bark (e.g. Echinodium prolixum, Plagiochila killarniensis, Lepidozia cupressina, Myurium hochstetteri, Geocalyx graveolens, and the ferns Hymenophyllum tunbrigense and Elaphoglossum semicylindricum), soil (Bazzania azorica, Pallavicinia lyellii), and rock (Jubula hutchinsiae). Drepanolejeunea hamatifolia and Colura calyptrifolia are common epiphylls on Laurus. At the higher altitudes, as on the rim of the caldeira of the highest mountain Serra Santa Barbara, Juniperus becomes prevalent but this finally succumbs to vigorous hummocks of Sphagnum subnitens and S. palustre in some parts of the cloud zone. Leptoscyphus azoricus and Herbertus azoricus are most frequent on Juniperus bark at higher altitudes. Cheilolejeunea cedercreutzii is quite plentiful in the extensive LaurusJuniperus forest inside Caldeira de Santa Barbara, a veritable bryologist’s paradise.

Regrettably, much of the native forest has been cleared to provide pastures (encouraged by EU subsidies) or to give way to forestry. Above and overlapping with the naturalised Pittosporum woods of the coastal zone is a belt of Eucalyptus globulosus plantation, while at higher altitudes there are shelterbelts and more extensive plantings of Cryptomeria japonica. A survey of epiphytes in these exotic forest types has provided some interesting preliminary findings. Pittosporum trunks support a sparse community in which Marchesinia mackaii, Frullania microphylla, Cololejeunea minutissima and Radula carringtonii are the main species, sometimes accompanied by the tiny Aphanolejeunea sintinisii. Tetrastichium virens and Sematophyllum substrumulosum are often present on moist tree bases. A similar community also occurs on Eucalyptus, although Heteroscyphus denticulatus is commoner here on moist trunk bases. A more acidophilous flora is present on Cryptomeria trunks, usually consisting of Dicranum scottianum, Campylopus spp, Hypnum spp, Plagiochila killarniensis, P. exigua, and occasionally Echinodium prolixum. Telaranea nematodes is often the dominant bryophyte at the trunk base. The results indicate that, although every effort should be made to conserve the remaining remnants of the native Azorean evergreen forest, the introduced trees provide a home for several interesting Azorean bryophytes and some examples are worthy of preservation for their bryological interest.

Dr Rosalina Gabriel (University Of The Azores): Ecophysiology of bryophytes in the native laurel forest of the Azores

The Azores archipelago, part of the Macaronesia region, is well known for a rich and diverse flora of endemic and relict species. The present investigation was undertaken against the background of massive and rapid decline of the Azorean forest due to human activity.

Seasonal growth rates (elongation) were determined for seven bryophyte species: Andoa berthelotiana, Bazzania azorica, Echinodium prolixum, Fissidens serrulatus, Frullania tamarisci, Lepidozia cupressina and Myurium hochstetteri. The majority have highly oceanic distributions and some are endemic, but F. tamarisci was included due to its ubiquitous distribution. The monthly growth rates were measured over one year in three examples of natural forest growth, and correlations with climate and microclimate were investigated. All species showed similar growth patterns, with the majority of growth occurring during late summer and early autumn. Growth of all species was strongly related to temperature, particularly with microclimatic values. The seven species measured in the field, plus Porella canariensis, were investigated in laboratory conditions, characterising their physiological attributes, and monitoring growth under controlled situations of light and water availability. All species showed low compensation and low saturation points. The liverworts B. azorica and L. cupressina were shown to be very sensitive to experimental conditions, seldom exhibiting positive growth. The concentration of photosynthetic pigments generally revealed a decrease in total chlorophyll and an increase in the concentration of carotenoids under high light conditions, while water deficit promoted a decrease in chlorophyll. B. azorica and L. cupressina were transplanted outside the forest, and both species were greatly affected by the transplant. The results suggest that B. azorica is more sensitive to photooxidation, showing the highest concentrations of lipid peroxides and the lowest concentrations of photosynthetic pigments; both species were extremely sensitive to low relative humidity levels.

Jenny Duckworth (Plantlife, London): Taking bryophytes back from the brink

Plantlife – the Wild Plant Conservation Charity – is Britain’s only national membership charity dedicated to conserving all forms of plant life in their natural habitats. Plantlife act as lead partner for 17 bryophytes listed as priority species in the UK Biodiversity Action Plan, and manages recovery projects based in England for these species through its ‘Back from the Brink’ programme. ‘Back from the Brink’ aims to reverse the declines suffered by threatened wild plants, and involves a combination of laboratory and field research with liaison, lobbying and hands-on management.

David Holyoak has been working on Petalophyllum ralfsii on behalf of Plantlife since 1997. He has carried out a survey of all current and historic sites in England, which included the discovery of a new site in Northumberland. At each site, population size has been estimated, and detailed descriptions provided of the site conditions, the habitats in which Petalophyllum occurs, and associated species, all of which provide further insights into the species’ ecology. In addition, liaison has been ongoing with site managers and land-owners in order to secure sympathetic management for the species. A three-year population study has been carried out at one site – Upton Towans in Cornwall – which has provided a new insight into the life cycle of Petalophyllum, namely that at least some plants remain concealed beneath the ground during all months of the year. This means that it is possible that population estimates for P. ralfsii may be on the conservative side. Fred Rumsey (The Natural History Museum, London) has carried out research on the population genetics of P. ralfsii using allozyme analysis, which has demonstrated that there is no significant genetic variation either between or within populations throughout the British range of the species.

Lejeunea mandonii has an extremely limited GB distribution, being confined to just a few sites in western Scotland and on the Lizard peninsula in Cornwall. It occurs in very small patches – in England the total area covered by the plant is less than one square metre. David Holyoak has been monitoring each English population since 1997 in order to gain an insight into the species’ dynamics. This has demonstrated that the populations appear to vary considerably from year to year, but the exact cause has not been established as yet. Securing favourable management for L. mandonii through liaison with site managers and land-owners is also important. This species seems to be exacting in its shade requirements – it cannot thrive in open sunlight, but dense canopies or adjacent scrub cast too much shade. A particular threat at its one open, coastal site is that of fire. There was a major heathland fire in the vicinity last year which fortunately missed the site, but it remains threatened since it is surrounded by dry and highly flammable gorse; the cutting of a firebreak is a priority.

Work is being commenced this year (2000) on seven other bryophyte species (Cryphaea lamyana, Riccia huebeneriana, Bryum warneum, Fissidens exiguus, Ephemerum stellatum, Sphagnum balticum and Tortula cernua), and there are plans to work on additional species during 2001. The initial stages of work on each species follow a similar basic pattern: a) collating all records, including an examination of herbarium material if necessary; b) carrying out a survey of current and historic sites, recording information on population size, habitat and threats; and c) producing a report including background information on the species and providing recommendations for future work. For example, Tom Blockeel is starting work in autumn 2000 on Tortula cernua – a species of Magnesian limestone spoil – which will involve a survey of recent and historic sites in Yorkshire, Nottinghamshire and Cheshire.

Sphagnum balticum, a species of oligotrophic bogs, has an extremely limited distribution in Britain, with one confirmed extant site in Scotland and two recent sites in England. Earlier this year, Johnny Turner confirmed that the species is no longer present at Thorne Moors. A detailed search of the other English site, Muckle Moss in Northumberland, involving a group of experts, is planned for October 2000 (I can since report that the species was refound during this search – see p. 53 of this Bulletin).

This is inevitably just a brief summary of some of the work going on, but hopefully it illustrates that Plantlife are now very much involved in bryophyte conservation and looking forward to taking more species on the road to recovery. However, this work is not undertaken by Plantlife in isolation, but in partnership with Government agencies from throughout the UK, those who manage the sites on the ground, and the many individuals in the bryological community who make a valuable contribution to the work.

For copies of reports on the species mentioned above please contact Jenny Duckworth at: Plantlife, 21 Elizabeth Street, London, SW1W 9RP; e-mail:

Gordon Rothero (Dunoon): Work towards bryophyte conservation in Scotland

A programme of work for the conservation of bryophytes north of the border was started in 1993 with survey work on lower plants commissioned by Scottish Natural Heritage (SNH) and organised at the Royal Botanic Gardens in Edinburgh by Brian Coppins and David Long. This was initially aimed at the Scottish species on the list of bryophytes that had just been added to Schedule 8 of the 1981 Wildlife and Countryside Act. Schedule 8 designation has probably had little impact in terms of practical measures to ‘save’ bryophytes but it has worked wonders in raising their profile within the conservation agencies. I carried out a good deal of the fieldwork for this programme, working my way up a steep learning curve, so that some species were rather better dealt with than others. The information collected went towards the production of ‘species dossiers’; these have a Part 1 which deals with the generalities of the species and a Part 2 which has details on localities, populations and site visits. This programme of work was expanded in the following years to include a number of Red Data list species.

Several bryophyte species are listed on Annex II of the EC Habitats Directive, and Species Action Plans have been prepared for priority species under the UK Biodiversity Action Plan. In order to support the conservation of these species, projects on three taxa (Buxbaumia viridis, Petalophyllum ralfsii and Jamesoniella undulifolia) were carried out. Obtaining baseline data on the distribution and population size of these species, each occurring at a single site in Scotland, posed different problems in each case.

Petalophyllum ralfsii is locally abundant at its Wester Ross site and a count of thalli is not feasible. All areas of damp sand supporting Petalophyllum were flagged and photographed, and in each case rough estimates of the number of thalli were made (giving a total population in excess of 25,000 thalli). This method should enable gross changes in the population to be monitored, which is probably all that can be achieved with what is basically a weed species.

Most stands of Jamesoniella undulifolia occur on Sphagnum hummocks, so the best plan at its Argyll site seemed to be to mark its presence or absence on the numerous hummocks on the site. A grid was marked out and the co-ordinates of each hummock and the presence or absence of J. undulifolia was noted, along with a simple measure of abundance. This worked well, with J. undulifolia found on some 93 hummocks. The down-side of the method was that it left the site looking like a battlefield and any re-survey (due in 2001) will need to be selective to reduce this collateral damage.

Buxbaumia viridis is different again, being very specific in habitat but also very sparse and difficult to spot despite its relatively large size. Flagging and photographing each stand is the obvious technique and this works well despite the low light levels in the ravine in northern Scotland where it occurs. I visited the site every two months to get some idea of the phenology of the plant. This revealed a major problem for the species in that, in my survey, 62% of all capsules observed fail to survive to dehiscence with circumstantial evidence pointing to slugs as the culprits.

The increased profile of lower plants has meant that non-governmental organisations such as the Royal Society for the Protection of Birds (RSPB) and the National Trust for Scotland (NTS) have taken more of an interest in the species which occur on the large tracts of ground that they manage. Recently, RSPB have funded a survey of the large population of Andreaea frigida on their reserve in the Loch Avon basin in the Cairngorms (see p. 58 of this Bulletin), and also more general surveys of other sites which have good populations of species such as Anastrophyllum saxicola, Cynodontium tenellum, Dicranum bergeri, Plagiochila atlantica and Orthotrichum speciosum.

The NTS has funded work to enable their site managers to become familiar with two species for which they have special responsibility: Bryoerythrophyllum caledonicum and Orthotrichum obtusifolium. Within the NTS reserve on Ben Lawers there is a large project on Meall nan Tarmachan to exclude grazing animals over all of Creag an Lochain and an area to the south of this, primarily to promote the development of willow scrub. NTS funded me to set up plots to monitor what happens to stands of some bryophyte species in places where the cessation of grazing may alter the habitat. The target species here included Hypnum bambergeri, H. vaucheri, Racomitrium himalayanum and Timmia norvegica.

However, the majority of work is still funded by SNH, with a survey programme managed by Stephen Ward in Edinburgh. They are paying me to provide baseline data on 27 species of bryophyte over the next two years (hard work I know, but someone has got to do it). These priority species range from relatively well-known rarities, such as Acrobolbus wilsonii and Lejeunea mandonii, to the more obscure Bryum uliginosum and Orthotrichum gymnostomum. The results so far have been mixed. Acrobolbus wilsonii seems secure, with some 27 widespread sites but is relatively frequent at only one locality. The situation with Lejeunea mandonii seems somewhat bizarre; despite much searching I could find it on only one tree in each of three ravines in Moidart and Skye. Bryum uliginosum and Orthotrichum gymnostomum remain inscrutable, although the search for the latter on aspens on Speyside revealed not only some superb woodland but also three new sites for Orthotrichum obtusifolium at Insh.

In general, conservation organisations north of the border have adopted a rather broader brush approach than those in England where the amount of money spent on just two species is probably more than that for the whole programme in Scotland. Though the work has revealed some specific problems, most populations of rare bryophytes seem relatively secure, provided that there is no marked change in habitat. It would seem sensible to try to establish ex situ cultures of species such as Orthodontium gracile and Orthotrichum obtusifolium, and to try to elucidate further the ecology of Buxbaumia viridis. However, it will come as no surprise if I suggest that the salvation of many of our rare species lies in the conservation of habitat rather than in measures targeted at individual species.

Tom Blockeel (Sheffield): Winter on a Greek island – the bryophytes of Evvia

The author spent a week bryologising on the Greek island of Evvia from 26 February to 4 March 2000. Evvia is a long narrow island situated close to the eastern coast of Greece and connected to it by a bridge. From north to south it is more than 150 km long. The geology is varied, and includes exposures of serpentinite/peridotite, schist and limestone. An earlier paper by Fröhlich (1961) includes reports of Dumortiera hirsuta and Scapania gracilis, but these could not be confirmed during the author’s visit.

The central part of Evvia is mountainous, the summit of Mt Dirfis exceeding 1700 m. The higher ground is snow-covered in winter. The author’s visit coincided with a spell of cold weather, during which snow fell at low altitudes. This impeded bryological investigations in the mountains. The villages of Steni in the central mountains and Limni on the NW coast were used as bases for exploration.

Coastal habitats

Outcrops of serpentinite/peridotite occur on the coast near Limni. Rocky banks and gullies in this area contained a limited bryophyte flora, which included Gongylanthus ericetorum, Tortula atrovirens, T. canescens and an as yet unidentified Entosthodon. An Ophioglossum (presumably O. lusitanicum) also occurred in this area.

Near the Galataki Monastery, some gravelly flats with an open growth of Pinus halepensis and various shrubs had a more diverse flora, including Corsinia coriandrina, Oxymitra incrassata, Fossombronia echinata, Petalophyllum ralfsii, Cheilothela chloropus, Didymodon tophaceus and Funaria convexa.

North-western hills

North of Limni is a range of hills which rise to nearly 1000 m. Some deep valleys and ravines dissect these hills. At lower levels, there is Pinus halepensis woodland with xerophytic bryophytes including Pleurochaete squarrosa, Bryum canariense, Homalothecium aureum and Scorpiurium circinatum. Locally, there is an abundance of Southbya tophacea and Eucladium verticillatum on wet rocks. Ephemeral species observed on disturbed ground included Sphaerocarpos texanus, Pleuridium acuminatum, Acaulon mediterraneum and Entosthodon fascicularis.

A small copse of deciduous oaks in the foothills near Akhladi contained a number of familiar British bryophytes: Riccardia chamedryfolia, Lejeunea cavifolia, Didymodon sinuosus, Eurhynchium praelongum and E. pumilum.

With increasing altitude, Pinus halepensis gives way to the Greek Fir Abies cephalonica. At the Drimona cataracts calcareous rocks supported Seligeria acutifolia, Fabronia pusilla, Anomodon viticulosus and Eurhynchium striatulum, and on open slopes Mannia androgyna, Targionia hypophylla and Tortula wilsonii. Rocks in the stream had Didymodon luridus, Dialytrichia mucronata, Bryum gemmiparum and Orthotrichum cupulatum. The epiphytic flora was rich, particularly in sheltered spots, and included Frullania dilatata, Neckera pumila, N. complanata, Leptodon smithii, Habrodon perpusillus and Pterigynandrum filiforme.

Central mountains

The central mountains include large areas of schist and some limestone.

A deep valley near Pagondas in the foothills contained Pinus halepensis woodland, with Platanus orientalis bordering the streams. Cheilothela chloropus was on the ground, and Fossombronia husnotii, Grimmia laevigata and Bartramia stricta on and about lightly shaded rocks. Crags of more exposed rock supported Tortula cuneifolia, T. wilsonii, T. atrovirens and Grimmia tergestina.

The slopes of Mt Dirfis are clothed with beautiful forests of Abies cephalonica and Castanea sativa, mixed with Platanus orientalis. Signs of early spring included beds of the pink primrose Primula vulgaris subsp. sibthorpii and the Greek hellebore Helleborus cyclophyllus.

Stream banks in the valleys on schist supported a rich flora which included Leiocolea turbinata, Jungermannia atrovirens, Marsupella emarginata, Scapania compacta, Radula lindenbergiana, Lejeunea cavifolia, Pogonatum aloides, Bartramia pomiformis, Pterogonium gracile, Isothecium alopecuroides and Eurhynchium pumilum. One deep and rocky ravine had an interesting mixture of southern species (Cephaloziella turneri, Gongylanthus ericetorum, Homalia lusitanica) and others more familiar in northern Europe (Porella arboris-vitae, Frullania tamarisci, Bartramia pomiformis). Dicranum tauricum was found on old logs in some of the ravines. Mineral soil on banks had Pleuridium acuminatum, Pohlia annotina, and by forest roads Tortula cuneifolia, T. canescens, T. wilsonii and Epipterygium tozeri.

At higher altitudes (700-1000 m), where not still covered by snow, the more open forest and rocks produced Porella cordaeana, Polytrichum piliferum, Grimmia laevigata and Plagiomnium cuspidatum. Deeper forest had Polytrichum formosum, Plagiomnium affine and Scleropodium tourettii in the ground flora, and the epiphytes Frullania dilatata, Orthotrichum spp, Zygodon rupestris, Neckera pumila, Leucodon sciuroides, Pterigynandrum filiforme and Homalothecium sericeum. Of special interest was a large population of Zygodon forsteri growing in knotholes of Abies cephalonica, and more abundantly in the interior of old water-filled stumps where the heart-wood had rotted away.


Fröhlich J. 1961. Bryophyten. In: Rechinger KH, Die Flora von Euboea. Botanische Jahrbücher für Systematik, Pflanzengeschichte und Pflanzengeographie 80: 455-459.

Field excursion to Greenham Common, 10 September 2000.

On the Sunday of the AGM weekend, a large group descended on this ex-military airbase, just to the south of Newbury. It is a Site of Special Scientific Interest (SSSI), designated in part for the large expanse (the most extensive in Berkshire) of Calluna vulgaris – Ulex minor heathland. After lunch, the uncharacteristically hot weather was seen as a good excuse to forsake the open heath for the relatively invigorating coolness of the wet alder gullies on the southern periphery of the site. The alder gullies have formed on clay pockets, with seepage zones and springs, and support Sphagnum carpets.

The heathland vegetation was maintained by decades of mowing when the military were managing the airbase, and hence scrub was kept at bay and the sub-shrub communities remained short with much open ground. As a result, this is probably the best heathland site for bryophytes in Berkshire. Prior to the BBS excursion, the total number of bryophytes recorded on the SSSI stood at 134 (although it is difficult to be certain whether some older records are located within the SSSI boundary).

Typical heathland plants seen were Polytrichum spp, Ceratodon purpureus, Dicranum scoparium, much Archidium alternifolium, some Lophozia bicrenata, Scapania compacta and Hypnum lacunosum var. tectorum. There is a curious mixture of calcicoles growing alongside the more normal calcifuge species of heathland; this is due to the large areas of concrete runways and taxiways having an effect on the adjacent heathland soils, and one finds Archidium alternifolium and Polytrichum piliferum intermixed with Encalypta streptocarpa, Aloina aloides and Trichostomum crispulum, the latter species now possibly gone from the chalk of the Berkshire Downs. Many people saw a strong population of Philonotis fontana around the margins of a wet depression; it was only recently discovered in small quantity on the dry heathland, and is probably the only extant site for it in Berkshire, so it was gratifying to find it in greater quantity. Climacium dendroides (a very rare plant in Berkshire) was also seen in a damp heathy depression.

Greenham is a stone’s throw from Ron Porley’s English Nature Office, and he has made many records, some new to the vice-county, from the heathland areas over the years. However, we managed to add 15 species previously unrecorded from the site, including Lophocolea semiteres (David Long) and Schistidium crassipilum (Nick Hodgetts), both new to VC 22. David’s discovery of Lophocolea semiteres on a sandy bank under birch is a further indication of the spread of this plant in Britain, although there is no way of knowing how long it has been at Greenham. The bank is probably no older than 50 years, and it should be possible to estimate its age more accurately by some research into land changes when in military ownership. There was some interesting discussion going back and forth between Herman Stieperaere and others as to whether it was indeed this species or L. heterophylla. Confirmation had to wait for microscopic study.

The best find of the day has to be Thuidium abietinum subsp. hystricosum, detected by Mark Pool, Ray Tangney and Neil Bell in an area of stony grassland. This probably represents its only extant site in VC 22; it was reported from Cookham Down pit (date unknown) but could not be re-found by Jeff Bates and Se< n O’Leary in 1994 (Bates, 1995), and has not been seen on Combe Hill since it was recorded there by E.W. Jones in 1947. Another very good find, Rhytidiadelphus loreus, was made by Angie Newton and Neil Bell in birch-oak woodland which fringes the heath. This moss of humid habitats is very sensitive to atmospheric pollution and has declined in many areas; it is very rare in Berkshire, known from just four 5-km squares (Bates, 1995), although it may well be a recent colonist following the amelioration of pollution levels. Amongst the other new site records were Ephemerum serratum var. minutissimum, Didymodon tophaceus (both in the heathland), Plagiothecium latebricola (alder gullies), Orthotrichum pulchellum, Cryphaea heteromalla and Leskea polycarpa (in the marginal wooded areas). Five Sphagna were seen in the wet alder gully areas: S. flexuosum, S. squarrosum, S. capillifolium, S. palustre and S. subnitens.

Many thanks go to Mark Hampton, Greenham Common Ranger, for navigating us around this deceptively large site.


Bates JW. 1995. A bryophyte flora of Berkshire. Journal of Bryology 18: 503-620.

Ron Porley


University of Reading, Reading