BBS > Activities > Meetings and Workshops > Previous > 1984
Meetings of the BBS - 1984
Brecon, 12-17 April
From the initial get-together in the bar at the Castle, this promised to be a memorable meeting and the enthusiasm both of the members and the weather subsequently made this a reality. All sites visited were in v.-c. 42.
The chosen sites all lay within the Brecon Beacons National Park and it was thought to be appropriate that on the Thursday morning, 12 April, an introduction to the area's geography and geology should be given at the mountain centre at Libanus. In the event, the member of the NP staff who was to have given the talk was not available and Ray Woods, our local member and assistant Regional Officer for the Nature Conservancy Council in Breconshire, gave a brief introduction to the week's programme.
A short distance away was the first site, Traeth Mawr, a small raised mire with peripheral wet flushes, managed as a reserve by the Brecknockshire Naturalists' Trust. Here Scorpidium scorpioides was much in evidence in the peaty flushes along with Drepanocladus revolvens, *D. exannulatus var. exannulatus and Plagiomnium elatum. The raised mire supports seven common species of Sphagnum growing amongst which was noted Odontoschisma sphagni and Mylia anomala, now scarce species in mid-Wales due to the general decrepitude of peatlands. Find of the week was possibly Joan Appleyard's *Dicranum leioneuron previously only known in Wales from raised mires in Cardiganshire. Lunch was a rewarding experience for some of us, taken on a roadside verge surrounded by Hypnum lindbergii and Archidium alternifolium.
After lunch, a move was made to the River Usk, a few miles east of Sennybridge, where we were joined by a number of members from the Reading area and the afternoon was spent searching the river-banks and boulders, the latter well exposed due to the low water level. Orthotrichum rivulare was abundant on riverside trees, from where Tortula subulata var. subinermis was also recorded. An old record for Epipterygium tozeri was confirmed and Ulota phyllantha, a scarce species in mid-Wales, was also seen.
13 April. The River Nêdd at Pont-melin-fach below Ystradfellte was the venue. This wooded valley is owned by the Forestry Commission but the area near the river is relatively undeveloped. Downstream from the bridge the rock is Millstone grit with a characteristic 'acid' bryophyte flora, and luxurious patches of Jamesoniella autumnalis and Dicranum fuscescens were not uncommon on the trees and rocks. On a stump was found Dicranum flagellare, a second county record, and other notable species included Dicranodontium denudatum and fruiting Diphyscium foliosum. Lunch was delayed to allow a visit to be made to a most impressive waterfall a few hundred yards further downstream.
Upstream, in complete contrast, the rocks were flushed with lime-rich water and prolific growths of Neckera crispa hung in curtains from the outcrop, providing a very different impression of a plant familiar to those living near the chalk grassland of the south-east. Eucladium verticillatum andCratoneuron commutatum var. commutatum had reacted with the water to produce large deposits of tufa, forming a substrate for Cololejeunea calcarea. The high relative humidity and possible absence of recent disturbance was reflected in the presence of Bazzania trilobata and both Wilson's and Tunbridge filmy ferns.
14 April. Saturday found the party, now 28 in number, at Craig-y-Rhiwarth in the River Tawe valley near Craig-y-nos Country Park. The initial climb up the hill from the carpark was through dry limestone woodland. Nowellia curvifolia was seen in an uncharacteristically exposed position whilst logs elsewhere in this wood proved fruitful with Dicranodontium denudatum, Tritomaria exsectiformis and Lophozia incisa recorded, the latter two by Jean Paton.
Lunch was enjoyed in brilliant sunshine, sheltered by the ridge from a cutting east wind. A descent through a natural rock arch resulted in the rediscovery of the near century old record Tortella nitida made by the Rev. A. Ley. On shaded, wooded cliffs Seligeria acutifolia was noted, here in a new locality remote from all its previously known Brecknock sites. Other species of note seen during the day included Scapania aspera, Riccia warnstorfii and Orthothecium intricatum.
Time allowed a short visit to the National Trust-owned Henrhyd Waterfall; the gorge of the Nant Llech here cut into coal measure shales and sandstones. Intrepid members examined the rocks behind the falls and in the gorge below. The abundance of Leiocolea bantriensis and Blepharostoma trichophyllum was notable, together with Tetrodontium brownianum on damp shaded rocks. Fissidens celticus was observed on a steep bank by the path.
15 April. On Sunday the banks of the River Usk were again visited, at Llangynidr Bridge, where the character of the river is quite different and large sandstone boulders are a feature. A search above and below the bridge produced Schistidium alpicola var. alpicola, Bryum gemmiparum (a national rarity not seen in the county since 1914), Pohlia lutescens, Epipterygium tozeri, Fissidens crassipes (second county record), F. rufulus, Barbula trifaria and B. spadicea. On tree bases Orthotrichum sprucei, O. rivulare and Scleropodium cespitans were frequent.
In the afternoon, the nearby Tal-y-bont reservoir was the centre of attention but the banks proved unrewarding and the party split up to examine the head water streams and cliffs of Craig-y-fan Ddu. Richard Fisk's discovery of Splachnum sphaericum on sheep dung, apparently not previously noted from the Beacons, was the only notable find.
16 April. Monday saw a return to the limestone, to the cliffs and quarries of Dyffryn Crawnon. Hail showers pursued the party up the valley, where part of the steep, predominantly ash, woodland is a Naturalists' Trust reserve. The quarries above, which had been worked in the recent past for limestone, proved disappointing owing to the extreme dryness; however, the line of the tramway above and below less disturbed cliffs was followed round the head of the valley until the transition to the Old Red Sandstone was indicated by the abundance of fruiting Bartramia pomiformis. Species of note on the limestone included Seligeria pusilla, S. acutifolia and Encalypta vulgaris. The party split, those returning to the valley floor noting beneath a limestone face, Orthothecium intricatum and Plagiopus oederi. A more wide-ranging group recorded Lophozia excisa, Riccardia palmata, R. sinuata, Cephaloziella hampeana and Mnium marginatum. Marcus Yeo collected a Scapania which Jean Paton confirmed to be *S. lingulata, new to Wales. The ash woodland provided few notable epiphytes, Pterogonium gracile being the exception.
P. J. PORT & R. G. WOODS
17 April. Although the wind had changed to the South for the last day, it was still cool and became cloudy, after a clear start. The approach to the Pen-Moel-Allt woodlands involved a circuitous and somewhat alarming convoy through the back streets of Merthyr. The clay-and-gravel track had Archidium alternifolium, and soon limestone appeared in the banks and walls with large cushions of Ctenidium molluscum, Barbula recurvirostra, well-grown Neckera crispa, and other species for the recording card. Soon, our party - of thirteen - cut down through very dense Larch to the north end of the Pen-Moel-Allt cliffs, a north-east facing scarp of Carboniferous limestone overlooking the Afon Taf Fawr. The scarp consists of a series of low limestone cliffs above steep - and rather slippery - slopes of clay and scree, with open Ash, Wych Elm, Oak and Hawthorn on and between the outcrops. To southward the slope steepens, and a tall cliff at some 300m altitude forms the major outcrop. In the many dry and damp habitats present bryophytes were abundant, with such species as Scapania aspera, Thamnobryum alopecurum, Plagiochila britannica and fruiting Ctenidium molluscum. Small species of the bare rock were Seligeria acutifolia, Cololejeunea calcarea and Tortula intermedia. In cracks and on soil-covered ledges was a rather confusing form of Trichostomum brachydontium. In general the cliffs were dry, and in only a few places was water-seepage evident, with Orthothecium intricatum and Jungermannia atrovirens. On trees were good growths of Lejeunea cavifolia, an d one alert member spotted two patches of Ptilidium pulcherrimum on an oak-trunk. Besides the 105 species of bryophytes we saw fine colonies of all three Polypodium ferns, and Mr Nethercott pointed out Sorbus leyana, a Whitebeam microspecies completely restricted to this valley, and the local S. rupicola.
Later in the afternoon on the return to Brecon we stopped at a gully on Craig Y Fro, a frowning rough cliff by the road just north of the pass. The time available, however, proved totally inadequate, and we retreated with fine fruiting Isopterygium pulchellum as perhaps the best find. The richness of this area was in fact revealed by a "splinter-group" of three members, who spent the whole day on the nearby - and much more extensive - Craig Cerrig-gleisiad, recording 150 species. Among many good finds were Eremonotus myriocarpus, Anoectangium aestivum (c.spor.), Grimmia torquata, and Isopterygium pulchellum.
In the evening eleven remaining members were made welcome at a restaurant in Brecon. We had a room to ourselves, and a most pleasant meal, amongst other things memorable for the sight of certain ladies of the group in evening attire, and for the production, from somewhere, by one of these ladies, of a pocket-lens to identify an ambiguous object in someone's sweet-course. The meal proved a very satisfactory way to round off the week: we toasted the health of the hard workers who had arranged for us such a varied and successful week - especial thanks to John Port, local secretary, and Ray Woods, NCC representative, who chose the sites so well.
F. J. ROBERTS
Wooler, 19-24 July
Northumberland was last visited by the BBS in 1963, and it had been well studied by Miss Lobley and J. B. Duncan before that time. It is therefore well known bryologically and we did not expect new records to be found easily. However, it is a county with a good range of different habitats even though the rainfall is not so high as more westerly areas. The rainfall was particularly low for some months before the meeting, and the six members attending found the bryophytes were mostly very dry. Weather that is bad for bryophytes is not necessarily so for bryologists, and if the drought caused some inconvenience it also brought the benefits of fine warm days for all of the excursions. All localities visited, except Grasslees Wood (v.-c. 67), were in v.-c. 68.
19 July. The Henhole, Cheviot. The party began by exploring the peaty banks and flushes of the College burn below Henhole, where Meesia uliginosa was found with sporophytes. The weather was overcast and cool enough to allow easy climbing up to the rocks on the North facing side of the valley. Here Peter Martin discovered Rhabdoweisia crenulata, while Grimmia torquata and Funaria obtusa were also found on and among the rocks. The saprophytes Tetraplodon mnioides and Splachnum sphaericum were noted on the screes and Robin Stevenson found *Hygrohypnum dilatatum in the stream. As might be expected, the flushes were rather dry which perhaps led us to overlook some species, particularly the hepatics. Barbilophozia barbata was found, however, and the three more common species of Gymnomitrion, G. concinnatum, G. crenulatum and G. obtusum. The day ended in warm sunshine with the party exploring the crags of Brayd on hill. These yielded more Splachnum sphaericum but were too dry and acidic to support a very varied flora.
20 July. Below the ruins of Norham Castle, the River Tweed forms a natural boundary between England and Scotland. Here the party explored the boulders and wooded banks on the Northumberland side of the river, in search of the elusive Hyophila stanfordensis and other rarities. Although known from the area it was not found, and Tortula muralis var. aestiva which had been expected (and promised) also failed to materialise. This variety has long been known to occur at Norham and was collected as recently as 6 months before the meeting. In all of the places that I had previously seen T. muralis var. aestiva, however, only the var. muralis could be seen! I suspect that the dry summer may have resulted in a change of phenotype, but my observations continue. Marcus Yeo justified the visit by finding Barbula nicholsonii and Gyroweisia tenuis on boulders by the river before the party moved on to Holy Island to eat a packed lunch b y the sea.
In the afternoon bryology was hampered by several factors. Firstly, all the bryophytes were quite dry except in the wettest of the dune slacks and secondly, being almost on the beach on such a glorious summer afternoon, everyone felt the attractions of traditional seaside pursuits. Nature was against us too, and had produced a fine display of Orchids (including Epipactis palustris) and butterflies (Dark green fritillaries, blues and Graylings) to distract us. The group displayed great single mindedness and compiled a reasonable species list. They were rewarded with Catoscopium nigritum, Petalophyllum ralfsii and Moerckia hibernica. *Campylopus introflexus was no doubt previously overlooked as it was noted in several other localities during the week. Giles Clarke, Marcus Yeo and I left to spend the remainder of the afternoon at Newham Fen, an ancient woodland fragment now managed by the Nature Conservancy. The fen was almost inpenetrable in parts with dense undergrowth which precluded the development of a diverse bryophyte ground flora. A central clearing proved to be rich in orchids (and horseflies) and provided more species for the rather meagre list. It was rumoured that the remainder of the party were delayed in a Lindisfarne Tea Room. In any event the rest of the week was beset with seditious talk of cream teas!.
21 July. The Bizzle, Cheviot. Joined for the day by David Long, the group enjoyed a full and energetic day of bryology. The Bizzle was found to be the meeting's richest locality and proved an interesting comparison with the adjacent Henhole. In contrast to the peaty flushes in the lower parts of the Henhole, the lower reaches of the Bizzle burn had earth banks and provided different habitats. David Long soon located *Fossombronia fimbriata (new to England) and *Haplomitrium hookeri here, and further upstream more basic rock was found than on the Henhole excursion. *Cololejeuna calcarea was collected on the rocks at the northern end of the crags, together with Grimmia incurva and Schistidium strictum. Further along the crags some species seen at the Henhole were found again, but *Scapania aequiloba, *Leiocolea heterocolpos, Dryptodon patens, Philonotis arnellii, *Anomobryum filiforme var. concinnatum, Pseudobryum cinclidioides and Radula lindenbergiana were new. Undoubtedly, many of these finds were due to the additional expertise of David Long, but the overall impression was that good bryophyte habitats in the Bizzle were more abundant than in the Henhole. Near the head of the ravine several members collected Kiaeria blyttii on boulders, Marchantia alpestris in a flush and Blasia pusilla on a soil bank. At this point, overwhelmed by new finds, half of the party decided to descend, while the other pressed on to the summit of Cheviot. This proved to be only a few hundred yards away and Pohlia ludwigii and Sphagnum fuscum were found on route.
22 July. A more relaxing day, the morning of which was spent at Black Lough, a bog on Alnwick Moor. The peaty hollows, surrounding farmland and a hillside flush provided a respectable list of species but no rarities. Again drought was a problem and much of the Sphagnum surrounding the pool was so dry that it disintegrated when touched. A nearby pasture was chosen for lunch, after which Richard Libby found he had been sitting on Leptodontium flexifolium, which was a welcome addition to the species list.
Callaly Craig, a north-facing sandstone escarpment, was investigated in the afternoon. The acid sandstone boulders provided enormous quantities of Orthodontium lineare, and also Dicranum fuscescens, D. majus and D. scoparium growing side by side. Like a textbook demonstration, the three species were easy to distinguish by eye. At the summit of the ridge Lepidozia cupressina was very abundant growing with Bazzania trilobata. *Kurzia sylvatica was found here on a damp shaded ledge, the only new record of the day.
23 July. An active day began exploring the River Alwin in the Kidland Forest where Orthotrichum rivulare and Schistidium alpicola were found on boulders by the river. Following Allerhope burn upstream to Raven's Crag, we recorded a considerable number of saxicolous moss species, most notably Encalypta ciliata, Cynodontium bruntonii, Amphidium lapponicum and Grimmia donniana. Robin Stevenson also found Apometzgeria pubescens in rock crevices. Somewhat reluctantly the group moved on to the waterfall at Linn bridge where Eric Watson and party were already bryologising. The riverside rocks and rock ledges were bound to be rather dry, but Eric Watson found Grimmia affinis, Marcus Yeo Orthotrichum rupestre and Peter Martin *Fissidens rufulus.
Grasslees Wood (v.-c. 67) a semi-natural birch-alder woodland near Elsdon was visited in the afternoon. A comprehensive species list was obtained for the Northumberland Wildlife Trust who now manage the wood as a wildlife reserve. Giles Clarke discovered Ptilidium pulcherrimum and Dicranum montanum on birch trees, while crags above the wood supported Lepidozia cupressina and Bazzania trilobata.
24 July. The morning was spent at Roddam Dene, a steep-sided wooded valley on conglomerate rock. The rocks and fallen trees made access difficult but *Hypnum mammillatum, Barbula spadicea, Nowellia curvifolia and Gyroweisia tenuis were noted. Unfortunately early records of Rhabdoweisia crenulata and Ulota drummondii were not confirmed.
In the afternoon another Cheviot locality, the Harthorpe Valley, was visited. We were again joined by Eric Watson, who explored Harthorpe burn while the main party concentrated their attention on Easter dene near Langlee. The dene contained many basic rock faces which supported Distichium inclinatum and Gymnostomum aeruginosum. Cynodontium jenneri was quite abundant on rocks and turf ledges but no trace was found of Rhodobryum roseum previously recorded from this locality.
The meeting was suitably concluded with a substantial five course meal at the Ryecroft Hotel.
In the attractive setting of the Manor Hall of Residence, about fifty members enjoyed what can be fairly described as a bryological compendium, for the programme encompassed a vast range of current activity in the subject. They heard how some of the most modern and sophisticated of techniques have been brought to bear on the meaning of oblique cross walls in caulonemata and of endophytic fungi in hepatics. They heard, also, a critical and useful assessment of additions to the British flora that have been identified by astute observers. Our fascination with the British flora, however, was ably transferred overseas by one of our honorary members, who described his longstanding and continuing interest in liverworts of Africa, and by another speaker, who introduced us to the bryophytes of the Adirondack Mountains. The audience politely accepted a substitute paper on bryophyte sex-chromosomes, and all of us were enchanted by the joint presentation, by two further speakers, of stereoscopic photographs. Summaries of all these papers follow.
Dr. J. DOONAN (John Innes Institute): "The microtubule cytoskeleton of Physcomitrella patens."
Indirect immunofluorescence can be used to visualize the microtubule cytoskeleton of cells within intact colonies of Physcomitrella patens. Microtubules are proteinaceous fibres which - by providing a cytoplasmic scaffold - play key roles in many morphogenetic processes in all eukaryotes. Studies on microtubules in mosses have concentrated on their role in the control of tip growth of protonemata, and how the re-orientation of cross-walls is related to development.
Protonemata grow solely by tip growth: therefore the mechanism by which tip expansion, as opposed to uniform expansion of the entire cell surface, is of interest in terms of morphogenesis. At the tip, microtubules extend into and completely fill the apical dome where they appear to end as foci. When treated with a carbamate herbicide (CIPC) which supposedly interacts with microtubule- organising centres (MTOCs) the tips become swollen, at the same time as the microtubules display aberrant distributions such as asters and starbursts. Disruption of MTOCs, therefore leads to misshapen tip cells
Caulonemata possess oblique cross-walls whereas chloronemata have transverse cross-walls. The process of cross-wall re-orientation, is foreshadowed at anaphase by a large increase in the numbers of spindle pole to cortex microtubules. These are associated with a tilting of the mitotic spindle and this oblique device is then separated by a correspondingly oblique cross-wall. Treatment with anti-MT drugs prevents their appearance, and also prevents the re-orientation. The orientation of the cross-wall is controlled by the direction of light, such that the leading edge of the oblique cross-wall is closest to the light source. During side branching in sub-apical cells, the nucleus returns to the cross-wall and divides so as to form a side branch on the side wall nearest the leading edge of the cross-wall. The side branch is thus initiated in the direction of the light source present when the mother cell was formed. The microtubular cytoskeleton plays a major role in reorientati on of the cross-wall, migration of nucleus to the site of division as well as in division itself.
The study of the cytoskeleton may lead us to a fuller understanding of now the morphology of plants is controlled at the macro-molecular level.
Mr A. C. CRUNDWELL (Headley Down): "The introduced bryophytes of the British Isles."
We shall never have a complete knowledge of the bryophyte floras of past ages nor learn exactly how those species that did not survive the Ice Age within the British Isles reached these shores. For practical purposes we may accept as native all species that were here before about 1500 A. D., when traffic with North America and South Africa started to become significant.
The evidence that a particular species is an introduction is never direct, but always circumstantial. This evidence is of six kinds:
Of course none of these criteria is absolute, and there is plenty of room for dispute about the status of individual species.
Thirteen species may be definitely accepted as introductions, or at least as recent immigrants: Riccia crystallina, R. rhenana, Telaranea murphyae, Lophocolea bispinosa, L. semiteres, Atrichum crispum, Campylopus introflexus, Tortula amplexa, T. rhizophylla, Grimmia crinita, Orthodontium lineare, Bryum apiculatum agg. (found on St Mary's, Scilly, in 1977) and Eriopus apiculatus. There are four more that may well be introductions, but less certainly: Tortula freibergii, Hyophila stanfordensis, Trichostomopsis umbrosa and Gyroweisia reflexa. The four following have been suggested as introductions but are more probably native: Fossombronia incurva, Telaranea nematodes, Campylopus pyriformis and Tortella inflexa. Fissidens lindigii (Hampe) Jaeg. (F. orrii (Lindb.) Braithw.) probably never grew out-of-doors in the British Isles.
A total of seventeen certain or possible introductions is very small in comparison with the large number of introduced angiosperms. This is no doubt mainly because very few foreign bryophytes are deliberately cultivated. Also relevant are the much wider geographical distribution of most bryophyte species, so that incoming propagules must often be those of native British species, and the fact that ports and docks, such a prolific source of alien angiosperms, are relatively inhospitable places for bryophytes and are rarely visited by bryologists.
At least seven of these seventeen species seem to have been introduced independently more than once - perhaps they are associated in their native haunts with favourite horticultural or other imports. Thirteen of them are dioecious and in no less than seven both male and female plants have been introduced; and these grow together except in Telaranea murphyae. Introduction is evidently not always by the single propagule. It is remarkable that seven of these species are found on the Isles of Scilly, five of them being present on the island of Tresco. Planting shelter-belts and making fields and gardens on a barren island creates new ecological niches with no native plants to occupy them but available for colonisation by any bryophytes accidentally brought in when foreign vascular plants are imported.
Dr M. E. NEWTON (University of Manchester): "Sex chromosome evolution in bryophytes. "
Sex chromosomes in bryophytes are of two types; (1) morphological, of which the X is larger than the Y and also possesses more heterochromatin, and (2) structural, which are seen to differ only in that the Y includes more heterochromatin that the X. In diploid dioecy, where a larger X than Y chromosome occurs, it is usually ascribed to differential erosion of parts of the Y as a result of an increasing genetic load and the absence of crossing-over during meiosis. Difficulties in applying the theory to haploid dioecy have led to the development of several new theories. That of Bull (1978) suggested preferential addition to the X. Like Blute's (1983) theory, however, it took no account of structural sex chromosomes. Smith's (1978) theory of Y chromosome deletion, however, while adequate for structural sex chromosomes, did not address the problem of morphological X chromosomes having more heterochromatin than the Y.
A theory to accommodate all known facts relating to bryophyte sex chromosomes (Newton, in press) was therefore put forward. It recognizes the possibility that dioecism may have arisen more than once, essential steps in the argument being that (1) a monoecious gametophyte must have the potential to initiate and develop male and female sex organs, (2) once dioecism arose, the developmental potential of the opposite sex could be seen as redundant and might be suppressed in the form of facultative heterochromatin, (3) there may be more secondary sexual characters associated with femaleness; more heterochromatin could therefore be expected to occur in the male-borne Y- chromosome than in the X, (4) these structural sex chromosomes would be expected to include equal amounts of achiasmate heterochromatin in the sporophyte generation, (5) accumulation of blocks of constitutive heterochromatin could be expected to protect sex-specific genetic information, of which there may be more i n females than in males, (6) erosion of redundant facultative heterochromatin could be expected, there being more in males than in females, (7) the result would be morphological sex chromosomes.
Dr E. W. JONES (Oxford) and Dr A. J. HARRINGTON (British Museum, Nat. Hist.): "African hepatics."
The coastal regions of West Africa from the Congo to Gambia are in the zone of high rainfall forest: mountains are few. In the forest hepatics are practically confined to tree boles, branches in the canopy, rotting wood, and the leaves of phanerogams and pteridophytes. Some of the species (e.g. Lophocolea spp., Riccardia spp., Aneura, Cephalozia spp.) will be readily recognised by a temperate bryologist as belonging to familiar genera, but the dominant forms belong to genera which will be unfamiliar, with a great preponderance of Lejeuneaceae; out of 67 species collected in the Benin forests in 1947-8 47 were Lejeuneaceae. Species of Plagiochila belonging to sections of the genus characterised by terminal branching (absent from cool temperate climates) are also conspicuous. Further north and south in climates with a strong dry season is savanna, which has been unduly neglected by bryologists. Here the hepatic flora is indeed poorer than that of t he forest zone, but the species are different; they include ephemerals of genera such as Riccia and Fossombronia which grow on the ground during the rainy season.
By contrast the East African lowlands are dry even on the coast, but there are numerous groups of often spectacular mountains arising abruptly out of the arid plains to misty heights where the boughs of forest trees are thickly clothed in Herberta spp., Plagiochila spp., Bazzania spp., and many Lejeuneaceae. Thus the East African hepatic flora is predominantly that of wet mountains whereas that of West Africa is predominantly a flora of wet lowlands; this latter element is almost absent from East Africa.
Some readily recognised and characteristic species of these various floras were illustrated by slides (many of them provided by the British Museum) and also, in an exhibit, by specimens. The exhibit also showed some historic specimens from the British Museum, including those collected by Palisot de Beauvois in Nigeria in 1787-8, the first hepatics ever to be brought back from Africa.
Dr and Mrs H. L. K. WHITEHOUSE (University of Cambridge): "Stereoscopic photography of bryophytes. "
Stereo-photography involves taking two photographs of the subject from slightly different viewpoints. This can be achieved either by using a two-lens camera, or by taking two photographs in succession with an ordinary single-lens camera and displacing the camera between the exposures. Photographs taken by both methods were shown. The displacement method has the disadvantage that any movement of the subject in the interval between making the two exposures becomes evident. On the other hand, standard stereo cameras available on the market have the lenses set at the average human eye separation, which results in distortion if the subject is closer than 2 m. Yet it is close-up stereo photography that is so rewarding and which is needed in any case for small objects such as bryophytes. The lens separation then needs to be one thirtieth of the distance of the subject. Thus, with a moss 15 cm from the lens, the camera needs to be moved laterally 5 mm before taking the second photo graph. Many of the close-up photographs shown were taken with a home-made stereo camera with adjustable lens separation.
For showing stereo-photographs a twin-lens projector was used containing polarized filters and the audience wore spectacles with complementary filters. A metallic screen is necessary. A diverse range of bryophytes was shown, including views of the habitat of some species. Stereo-photography is valuable in enabling one to become familiar with the field appearance of the plants, both when wet and when dry. It also allows one to visualize how species compete: for example, Eurhynchium striatum, Brachythecium rutabulum and E. praelongum were seen in one photograph interwoven in a complex way on a woodland floor. In conclusion, a few stereo-photographs of bryologists were shown.
Dr K. POCOCK and Prof. J. G. DUCKETT (Queen Mary College, London) "The alternative mycorrhizas: fungi and hepatics."
By contrast to the lack of intimate relationships between mosses and microorganisms, endophytic fungi are widespread in hepatics. Light and electron microscope studies have revealed these associations to be of three main types which almost certainly evolved independently in different groups of liverworts.
Basidiomycetous mycelia are invariably present in the stems and rhizoids in the majority of British members of the Jungermanniaceae and in other genera scattered through other families in the Jungermanniales (Marsupella, Saccogyna, Harpanthus, Southbya, Ptilidium). Amongst thalloid taxa this type of association is limited to the Aneuraceae and is highly developed only in Cryptothallus. The hyphae, with dolipore septa, but lacking clamp connections, form intracellular coils or pelotons within liverwort cells. Unlike the mycorrhizas of higher plants the fungus does not spread between the host cells (most likely a reflection of the absence of intercellular spaces in hepatics) but penetrates directly through the cell walls in the stems and extends into the substratum only via the rhizoids. Meristematic tissues, gametangia and sporophytes remain free from fungus. The distribution of the fungus is characteristic of each species. In Southbya it is restricted to a strand of cells running down the centre of the stems but in Tritomaria and Lophozia the ventral side of the stems contain a mosaic of infected and uninfected cells. A notable feature of the last two genera is the production of papillae projecting into uninfected cells from the walls contiguous with those containing the fungus. These wall ingrowths consist of fungal hyphae surrounded by liverwort wall material. The hepatic-fungus interface is highly reminiscent of that in vascular plant mycorrhizas with both partners possessing a normal complement of organelles.
The fungi found in British Marchantiales (except Ricciaceae where they are absent), and in Fossombronia, Petalophyllum and Pellia (Metzgeriales) are closely similar to those forming vesicular arbuscular mycorrhizas in vascular plants. An intramatrical mycelium comprises large trunk hyphae which give off profusely branched arbuscules. The fungi possess the distinctive reticulate vacuolation found in Zygomycetes and many vacuoles containing polyphosphate granules.
In the third kind of association, found in the Lepidoziaceae, Calypogeiaceae, Cephaloziaceae and Mylia anomala, the fungus is largely restricted to the rhizoids. The hyphae in Calypogeia proliferate in the basal parts of the rhizoids whose adjacent stem cells possess numerous wall ingrowths each comprising a hypha overgrown by hepatic wall materials. In other genera the fungi form dense coils within swollen rhizoid apices. These are especially numerous on underground axes which extend to depths of up to 20 cm in peaty substrata.
Mr A. R. PERRY (National Museum of Wales): "Incursions into the North American bryoflora."
Remarks were mostly confined to a comparison of the mosses of the British Isles with those of New York State, more specifically the Adirondack Mountains. The history of bryophyte study and collection in the State goes back to about 1830, but the first published work did not appear until 1866 when C. H. Peck listed 274 mosses and 66 liverworts. Over one hundred years later, in 1980, E. H. Ketchledge published his Revised Checklist of the Mosses of New York State which includes about 500 taxa. No similar published checklist of hepatics of New York is known to exist though Schuster's The Hepaticae and Anthocerotae of North America, when completed, should provide one. A quick count in Ketchledge's List reveals about 180 species not recorded in the British Isles. Taking the moss flora of the British Isles as about 700 taxa these figures indicate that there are about 380 taxa in the British Isles not recorded in New York State.
There is, though, a considerable common element in their moss floras and a British bryologist visiting New York State for the first time will experience a certain amount of familiarity with its bryoflora. There are, however, some pitfalls for the incautious. For example the common Hypnum is not H. cupressiforme nor H. mammillatum butH. pallescens (Hedw.) P. Beauv., though the differences may be subtle; the common woodland Thuidium is not T. tamariscinum (which is not recorded) but T. delicatulum; Mnium hornum is present, but is essentially montane; there are two species of Climacium, C. dendroides and C. americanum Brid., the latter rather commoner; Paraleucobryum longifolium, seen recently in the British Isles only on Cairngorm, is common on acid rocks in lowland forest; Thamnobryum alopecurum is absent, being "replaced" by T. alleghaniense (C. M.) Nieuwl.; Pseudolesk eella nervosa, a very rare montane saxicole in Britain is frequent on tree bases and logs in lowland forest in New York State.
Several genera absent from the British Isles are represented. For example, Thelia, placed by Crum & Anderson in their magnificent Mosses of Eastern North America (Columbia University Press, 1981), in the Leskeaceae with, i.a., Anomodon and Pterigynandrum, is characterized by laminal cells with very long and often branched papillae and usually spinose to ciliate leaf margins. Its three species grow usually on tree bark where they form light- to glaucous-green creeping mats. Forsstroemia, represented in the area by F. trichomitria (Hedw.) Lindb., is probably related to Cryphaea and like it usually grows on tree bark, but it superficially resembles a Leucodon. Drummondia, named after the Scottish botanist Thomas Drummond, is represented by D. prorepens (Hedw.) E. G. Britt. It is a member of the Orthotrichaceae but has long creeping stems with ascending branches. A species that may occur in the British Isles is Anacamptodon splachnoides (Froel. ex Brid.) Brid., commonly called the "knothole moss" from its propensity for growing in often wet or water-filled knotholes on tree trunks, often on Fagus spp. Its gametophyte is nondescript and therefore easily overlooked, resembling a rather scruffy Amblystegium; but it is frequently fertile when its capsule offers distinct features for recognition. Another possible British species is Sphagnum pylaesii which in the northern part of its range is often submerged in shallow pools near sea-level, but farther south, as in the Adirondacks, is often in montane habitats on granite rocks wet by seepage but not submerged.
The Annual General Meeting was held afterwards (Minutes in Bulletin 46) and was succeeded in the evening by a conversazione, during which the demonstrations listed below were displayed. Throughout the whole of the meeting, Dr D. C. Lindsay rendered invaluable service as local secretary. That he did so with unfailing good humour is a matter for admiration, and the Society is greatly indebted to him.
M. E. NEWTON
Field meeting - Wyre Forest
After torrential rain on the day of the Paper-reading meeting, participants in the field excursion on Sunday were able to enjoy a day of fine weather. About 25 members gathered, and were guided by Mr Peter Thomson to sites in the Wyre Forest, an area which has been fairly thoroughly investigated for bryophytes. Most people spent the morning searching along the banks of the stream in Park Brook valley and saw: Frullania tamarisci, F. dilatata, Trichocolea tomentella, Pellia endiviifolia, Hypnum lindbergii, Ulota crispa, Amblystegium tenax and a patch of Ctenidium molluscum assigned to the "woodland taxon".
Members gradually emerged from the stream valley to have lunch beside the path of the old railway line, before a somewhat depleted party set off at a more rapid pace towards Dowles Brook and Lords Wood valleys. The excursion provided several members with an opportunity to return to old haunts: Drs Longton and Greene visited a site where 15 years before, sporophytes were produced by Pleurozium schreberi following the transplantation of male plants, finding no trace of either sporophytes or male plants, but Martha Newton was able to locate a fine colony of Bazzania trilobata on a well-remembered boulder beside the path to Dowles Brook. Additional species recorded in the afternoon included Cephaloziella divaricata, Saccogyna viticulosa and Plagiothecium undulatum, and the list was enhanced by a new Vice-county Record provided by Jean Paton who discovered Jamesoniella autumnalis on a Sorbus torminalis trunk in the valley below Lords Wood.