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Meetings of the BBS - 1974

 

Spring Field Meeting 1974

Draguignan, Var, France, 3-10 April

The Spring Meeting, organized by Mr P. J. Wanstall, was held at Draguignan, chef-lieu of the Department of Var, France, from 3 to 10 April. Seven British members attended, and we had the pleasure of the company of our French member Monsieur Pierrot for three days.

Draguignan lies 23 km distant from Fréjus, the nearest point on the sea, at about 250 m alt. on the northern edge of a broad, highly cultivated basin of Triassic rocks. Immediately north of the town rolling hills of predominantly Jurassic limestone rise to altitudes of 300-500 m. Northwards the limestone hills continue to rise until, 20 km north of Draguignan, around the spectacular gorge of the river Verdon, they attain an altitude of 1000-1500 m; eastwards the limestone belt passes Into the Maritime Alps, while westwards it extends to the neighbourhood of Marseilles and Aix-en- Provence. To the south, bordering the sea, are massifs of hills with acidic rocks and igneous intrusions - the Maures to the west of Fréjus, rising to about 500 m, of Carboniferous and Precambrian grits and shales, and to the east of Fréjus the much more highly dissected Esterel, of Permian shales.

On 3 April we examined the limestone close to Draguignan, and on 4 April the more elevated limestone above the gorge of the Verdon. On 5 April we visited the famous Forest of Ste Baume, 30 km east of Marseilles, on limestone, 670-970 m alt. 6 April was devoted to the low sandy ground north of Puget (6-8 km northwest of Fréjus) and to the low siliceous hills around the gorge of the river Blavet just to the north. On 7 April one party visited the Esterel, which appeared so promising that we revisited it on the 9th, while the other party examined the low-lying limestone country to the west and southwest of Draguignan. On 8 April one party visited the limestone foothills of the Alpes Maritimes between Menton and Sospel, guided by Miss M. Campbell, while the other party visited various places on the coast near St Tropez and in the Maures. On 10 April three of us paid a quick visit to Roquebrune, a spectacular rocky hilt which forms a northeastern outlier of the Maures, apparently a neglected site which would repay more thorough examination.

It was scarcely to be hoped that we should make any outstanding discoveries, and many of our most interesting records, so far as distribution in France is concerned, merely confirm old records from the same districts by Boulay or Philibert - e.g. Fissidens serrulatus* ( Ravin de Perthus, Esterel), Epipterygium tozeri (near La Mole, Maures), Timmiella barbuloides (Brid.) Moenk. (Esterel? +). Mr Crundwell, however, recognised Tortula bolanderi (Lesq.) Broth, (new to Europe) in a shady lane at Ramatuelle, near St Tropez, accompanied by Fissidens algarvicus, Ditrichum subulatum, etc. We saw fewer than ten species of bryophyte which are not known from Britain, in striking contrast to the phanerogam flora, in which non-British species are overwhelmingly predominant.

[* Except when authorities are cited, the names of the bryophytes are those used in the two British Census Catalogues.]

[+ Not noticed in the field, but noticed by Mr Fletcher amongst Riccias that I sent him to grow, and has also appeared amongst Riccias, probably from the Esterel, that I am growing.]

French authorities (e.g. Flahault, in Coste's Flore de la France) place the boundary of the Mediterranean floristic region about 10 km north of Draguignan. Sunny earth banks and limestone rocks near Draguignan bear many thermophilous species such as Bryum canariense, Crossidium squamigerum Jur. , Desmatodon convolutus, Fabronia pusilla Rad. (on olive and Quercus ilex), Grimmia orbicularis, Tortula canescens, Pottia starkeana, Cephaloziella baumgartneri, Southbya tophacea, Funaria pulchella Philib. (not very rare, as the old authorities state, but apparently the common representative of the 'F. muhlenbergii complex' in the district). All these species are frequent, and were seen in many places, accompanied by more widely ranging species such as Aloina aloides, Bryum torquescens Bruch and Grimmia pulvinata. The thermophilous element very quickly disappears on going northwards, and the oak coppice (often very degraded) and limestone pavements above the gorge of the Verdon have an essentially continental European flora such as would be found on the Burgundian hills. Neckera crispa, Orthotrichum affine, O. speciosum and O. striatum, Zygodon viridissimus var. vulgaris (the only form seen during the week), Frullania dilatata and Radula complanata were abundant on tree boles, while Camptothecium lutescens and Hylocomium splendens are abundant on the ground. Rhytidium rugosum was frequent, and Tortula subulata var. graeffii was abundant on earth banks. Almost the only markedly southern species were Leptodon smithii (stunted, and confined to tree bases), Tortula princeps (stunted and rare), and Targionia hypophylla. North of Menton the mediterranean element disappears even more quickly, and in general the bryophyte flora resembles that of the lower limestone hills of eastern France, though marked by the remarkable luxuriance of certain species such as Neckera complanata, which draped Buxus branches with curtains up to 20 cm deep.

The Forest of Ste Baume is famous as an outlier of deciduous forest with beech, elm, ash, Quercus pubescens, holly and yew in a region where Pinus halepensis, Q. ilex, Q. coccifera and sclerophyllous scrub predominate. It occupies steep northern slopes at the foot of a range of cliffs in which is a cave where, according to a very ancient tradition, Saint Mary Magdalene ended her life as a penitent recluse. The site is certainly one with a locally enhanced precipitation (ca. 1000 mm, much of it as snow, which had not completely gone, compared with ca. 560 mm at Marseilles), but it is probably not unique in this respect, and the forest has survived because it has been protected for nearly a thousand years as a 'sacred grove'. The rich corticolous flora included Habrodon perpusillus, Leptodon smithii (luxuriant and fruiting freely), Leucodon sciuroides var. morensis, Radula complanata (highly gemmiferous, as everywhere where we saw it) all abundant, and Tortula virescens. On rocks and on the ground Anomodon viticulosus, Cirriphyllum crassinervium, Isothecium striatulum and Pterogonium gracile abounded; Myurella julacea var scabrifolia was mixed with other mosses on rocks. The southern slope of the hill presents a complete contrast, with bare rocky ground and open scrub of Cistus, etc. Phascum curvicollum, Pottia lanceolata, P. starkeana and Pterygoneuron ovatum (so hoary as to look like a different species from our English plants) were frequent, but pronouncedly mediterranean species were not seen.

The non-calcareous rocks and sandy ground near the coast afforded a great contrast to the limestone. Sunny rocks were often thick with Grimmia spp. including G. commutata, G. laevigata, G. tergestina Tomm. , and with Hedwigia ciliata. Campylopus polytrichoides was frequent on rock ledges in the Esterel and at Roquebrune. The following species were frequent or even abundant, and seen in many localities: Bartramia stricta, Barbula acuta, Bryum alpinum (often fruiting), Ceratodon chloropus, Camptothecium aureum (Lag.) B. , S. & G. , Eurhynchium megapolitanum, Funaria attenuata, F. obtusa, Scleropodium tourettii, Cephaloziella stellulifera, Gongylanthus ericetorum. The Esterel also yielded Cephaloziella turneri, C. calyculata, Fossombronia angulosa (also in the Maures), F. caespitiformis, F. husnotii and F. pusilla. On seasonally wet ground (usually flat, but occasionally near the bases of steep banks) Riccia crozalsii was frequent, usually accompanied by a larger persistently sterile Riccia which is presumably R. michelii; R. nigrella was very much rarer, seen only in the Esterel and on Roquebrune. Fissidens algarvicus was seen in two localities in the Esterel, and also near St Tropez. Corsinia coriandrina (Sprg.) Ldbg. was frequent in damp ground.

River banks, whether calcareous or not, often yielded Scorpiurium deflexifolium (Solms) Fleisch. & Loeske, Bryum gemmiparum (sometimes without gemmae), and Cinclidotus mucronatus.

Much of the interest of the week's experience lies in seeing some of our most local and unfamiliar British bryophytes growing in abundance, in obviously optimum conditions, and some of our familiar species growing in unfamiliar conditions. I have already named most of the first category; to them may be added Eurhynchium meridionale, Scorpiurium circinnatum and Tortula cuneifolia. Of the second category perhaps one of the most striking is Bryum alpinum, often abundant on dry rocks (though doubtless copiously irrigated during periods of rain) at very low altitudes. The frequency of Leiocolea turbinata emphasises its strong western Mediterranean tendency. By contrast, Lejeunea cavifolia (the only Lejeuneaceae seen) was very rare and only in exceptionally moist places (close to the stream in the Ravin de Perthus, Esterel) or outside the Mediterranean floristic region (Gorges de Verdon). Habrodon perpusillus is widely distributed in the lowland s of Mediterranean and Atlantic France - we saw it in several places - but its abundance in the Forest of Ste Baume perhaps throws some light on its apparently northern tendency in Britain. We may note that at Ste Baume it had as companions Pterogonium gracile and Myurella julacea, and reflect that all three species occur in the neighbourhood of Killin in Perthshire. On the other hand we may reflect that in view of the abundance of Pterogonium gracile in the forest of Ste Baume its occurrence beneath beech in the New Forest should not surprise us, despite its markedly western and northern distribution in Britain as a whole.

No account of the meeting would be complete without reference to the extraordinary proceedings after an informal dinner on 6 April, when all members from our President downwards, kissed and embraced Mme la Patrone, toasted her in champagne (it was her birthday), and danced far into the night. Some of us may be tempted to say, with Laurence Sterne, 'They order this matter better in France'.

E. W. JONES

 

Summer Meeting 1974

Caithness & Orkney, 25 August-6 September


Caithness, 25-30 August, 1974

The first week of the meeting was based on Thurso from 25 to 30 August. The aim was to cover ground in the most north-eastern part of Britain, little known to past British bryologists with the notable exception of the Rev David Lillie of Watten. The possibility of refinding some of the rarities recorded by him some seventy years ago added considerable interest to the meeting. About twelve members attended for most of the week; excursions were restricted to the northern and eastern parts of Caithness (v.-c. 109) except for one made by a member to W. Sutherland (v.-c. 108).

25 August. The day was spent on the dunes of Ackergill and Keiss Links fringing Sinclair's Bay. On the main dune ridge of Ackergill Links Hypnum cupressiforme var. tectorum* and Entodon concinnus were seen, also Bryum bicolor agg. * on a wooden footbridge. Fixed dunes on the landward side produced Bryum inclinatum and Amblyodon dealbatus. Keiss Links, after we had forded the Burn of Lyth, proved more interesting, the first find being Bryum marratii* on damp sand by a backwater. Hollows on the fixed dunes nearby contained Scapania aspera, Distichium inclinatum, Encalypta rhabdocarpa, Pottia heimii, Tortella fragilis in quantity, Catoscopium nigritum and Drepanocladus vernicosus. One member concentrated on the ubiquitous oatfields of the county. One such habitat at Skirza, near Freswick Bay, contained Ditrichum cylindricum, Dicranella staphylina, Bryum sauteri*, B. violaceum and B. rubens.

* New vice-county record throughout.

26 August. The first coastal ravine visited was that of the Dunbeath Water. Boulders in the stream bed a short distance above Dunbeath supported Solenostoma cordifolium*, Scapania subalpina and Barbula spadicea. A small stubble field nearby contained Anthoceros husnotii and Ephemerum serratum var. minutissimum*, Further upstream the valley became more wooded with considerable sandstone exposure. Shady rock faces supported Lejeunea cavifolia* and Bartramia pomiformis var. elongata*, while on the wooded slopes Fossombronia pusilla and Pohlia lutescens* were noted on soiI, Scapania nemorea* on a boulder and Orthotrichum pulchellum on hazel. By the river, detritus-filled rock crevices yielded Plectocolea paroica*. Further work was curtailed by heavy rain but one member continued to search oatfields. In one at Buoltach near Latheron, Ditrichum pusiIIum*, Pseudephemerum nitidum and Pohlia pulchella* were collected; another at Spital near Halkirk produced Dicranella staphylina and Bryum sauteri.

27 August. The morning excursion explored the partly wooded valley of the Strath Burn near Watten, from Strath southwards to Scorriclet. On a grassy riverside bank near Strath Weissia microstoma var. brachycarpa* was detected, considerably extending its known British range. On wooded slopes in the area Plagiothecium laetum* occurred on soil, and Pohlia rothii* mixed with P. annotina on a gravelly path. Towards Scorriclet basic flushes were conspicuous and contained Pellia neesiana*, Trichocolea tomentella, Mnium rugicum*, Acrocladium stramineum and A. giganteum. A search in a barley field near Strath revealed Bryum sauteri, B. klinggraeffii and B. violaceum. After lunch the party proceeded via Kensary to the Dubh Lochs of Shielton, and extensive Sphagnum-dominated system of treacherous pools on very acid blanket bog. Numerous Sphagna were seen including fine hummocks of S. imbricatum and S. fuscum. Associated species were Pleurozia purpurea, Campylopus brevipilus and gemmiferous Aulacomnium palustre. Tortula ruraliformis was noted on an outbuilding roof at Rowens.

28 August. The Links of Dunnet Bay, a locality well-known to Lillie, were chosen for the main excursion. A young conifer plantation provided shelter from the cold wind and its ditches and damp sandy hollows supported a rich bryophyte flora associated with Primula scotica: Tortella fragilis and T. inclinata were in abundance with Leiocolea bantriensis, Encalypta rhabdocarpa, Barbula revoluta, Catoscopium nigritum, Philonotis calcarea and Drepanocladus vernicosus. Beyond the wood exposed damp hollows contained fruiting Meesia uliginosa and Amblyodon dealbatus. Later in the day other localities yielded Bryum neodamense in quantity on damp gravel by the Loch of Mey, Nowellia curvifolia* on fallen trees in woodland at Castletown and Campylopus brevipilus and Bryum intermedium on spoil heaps in an adjacent 'flagstone' quarry.

One member ventured into the coastal part of West Sutherland (v.-c. 108) for the day, examining oatfields. In the best of these, at Calgarry Beg near Melvich, Ditrichum cylindricum, D. pusillum*, Pohlia pulchella*. Bryum tenuisetum* and B. rubens were found.

29 August. The sandstone gorge on the River Thurso at Dirlot was the venue for the morning. Here Lillie added Barbilophozia atlantica to the British Flora in 1901, and it was refound growing on dry rocks with Cynodontium bruntonii and Orthotrichum rupestre. Species found in the gorge itself were Cololejeunea calcarea and Seligeria recurvata on damp rock faces, Sphagnum teres in a flush and Polytrichum nanum on damp soil. Dicranella crispa* c.fr, occurred above the gorge on a sandy footpath. The fine weather prompted an afternoon visit to the north coast at Crosskirk Bay. A small oatfield there contained Dicranella staphylina, Bryum ruderale and B. violaceum, confirming the widespread occurrence of these species in the area. Careful searching of damp cliff-top soil nearby was rewarded with Archidium alternifolium, Tortella flavovirens var. flavovirens, Amblystegium serpens var. salinum, Bryum micro-erythrocarpum, Ephemerum serratum var. serratum* and Lejeunea patens* (the last in a damp grassy hollow),

30 August. Hilly ground below Warehouse Hill near Ulbster was chosen for the morning of the final day, and despite thick mist a good number of interesting species were seen. Patches of marshy ground produced Calypogeia neesiana var. neesiana*, Chiloscyphus pallescens*, Cephalozia leucantha and Sphagnum contortum. On mud by a partially drained loch below Warehouse Hill species of interest were Fissidens osmundoides* and Acrocladium sarmentosum. By Groat's Loch nearby were Fossombronia foveolata* and Haplomitrium hookeri*, both with mature sporophytes. An interesting find between the two lochs was Tayloria longicolla freely fruiting on damp peaty patches amongst heather. This species was known to Lillie from three other Caithness localities, but had not been seen in Britian for many years. Another oatfield search at Smerlie near Lybster produced Bryum riparium*. Weissia rutilans grew on a rock on moorland near Wha ligoe, Ulbster. After lunch the final excursion was a rather brief visit to the lower part of the Reisgil Burn at Lybster, a deep ravine cut through base-rich sandstone. Solenostoma pumilum and Hygroamblystegium fluviatile grew on boulders in the stream, while on the damp ledges above grew Blepharostoma trichophyllum, Scapania cuspiduligera*, Radula lindbergiana, Cololejeunea calcarea, Distichium capillaceum, Gymnostomum recurvirostrum , Eucladium verticillatum, Campylium protensum* and Rhynchostegiella pumila*.

During a very enjoyable and interesting week-mapping cards were compiled for twelve grid squares and a good number of rare species seen. Much credit must go to Mr J. K. Butler whose expert local knowledge and efficient organisation proved invaluable. Results of the week suggest that further work in the county, particularly in the remote western areas, on the high ground and in other coastal ravines, would be well worthwhile.

DAVID G. LONG.


Orkney, 1-6 September, 1974

The second week was held in Orkney (v. -c. 111 ). Only six members attended and one of them left on 4 September. The terrain was mostly sandstone and predominantly flat, nowhere rising to 1000 feet except on the island of Hoy, the only place where there were interesting gullies or ravines.

1 September. The first area visited was the Sands of Evie. Here we saw Dichodontium pellucidum var. fagimontanum and Tortella flavovirens, the only things worth mentioning. A short walk took us to the Broch of Gurness, at Aiker Ness. Pottia heimii and Grimmia maritima (noted frequently during the meeting) were seen and a fine patch of Pottia recta occurred near the Broch. Bryum micro-erythrocarpum* provided a vice- county record. A move was then made to some limestone outcrops at Aikerness. Lejeunea patens and Tortula subulata were the most interesting species seen here. Below the outcrops were calcareous flushes with Drepanocladus aduncus, D. revolvens var. revolvens and Scorpidium scorpioides. We parked for lunch in an old quarry at Arwick and then explored the Hill of Owarmo and Vishal Hill, in pouring rain. Funaria obtusa, F. attenuata, Archidium alternifolium and Bryum alpinum were the only relief in a dull area although Ephemerum serratum agg. was collected, the spores being too immature for identification of the segregate. On our return to the quarry a search among the abandoned ironmongery of Arwick was rewarded with Seligeria recurvata.

The morning of 2 September was spent in the Dale of Cottascarth (R.S.P.B.), a moorland area where many small streams originated, some of them too overgrown to provide bryological habitats. Philonotis calcarea, Cratoneuron commutatum and Grimmia stricta were found although most of the ground was acid. Leiocolea bantriensis and Bryum alpinum were seen and Pohlia rothii* and P. bulbifera* were collected on a track near Upper Cottascarth Farm.

After lunch, by kind permission of the owner, Binscarth Wood near Finstown, practically the only patch of woodland on the 'Mainland', was investigated. The stream flowing through the wood was badly polluted and although several species were added to the record card, nothing of interest was seen. We then moved on to the Loch of Wasdale. The shore of the loch was disappointing except for Bryum klinggraeffii* so we followed the stream up Wasdale. Here again the ground was mostly acidic with basic undertones, providing such species as Tortella tortuosa, Trichostomum crispulum and Philonotis calcarea. Grimmia alpicola var. rivularis was seen in the stream, Archidium alternifolium and Dicranella schreberana on the banks and Acrocladium giganteum and Chiloscyphus pallescens in a flush. In an old quarry on the hillside, Ptychomitrium polyphyllum was noted and Campylopus brevipilus occurred on moorland near the quarry.

3 September. A projected visit to Hoy was almost abandoned because of the atrocious weather but a report of qualified optimism from the local Meteorological Office encouraged us to go ahead and in the event we suffered nothing worse than some mist and an unusually vicious plague of midges. The Glen of Greor was chosen for exploration and proved quite rewarding, Nowellia curvifolia was found growing on peat as we climbed up to the Glen. In the Glen itself Antitrichia curtipendula was found, confirming a previous record for the locality. Isothecium myosuroides var. brachythecioides, Barbula ferruginascens, Bartramia ithyphylla, Fissidens osmundoides, Isopterygium pulchellum, Trichostomum brachydontium var. littorale, Leiocolea bantriensis, Herberta adunca, Tritomaria quinquedentata, Radula lindbergiana and Blepharostoma trichophyllum were seen and the following records for Orkney were made: Plectocolea subelliptica*, Gymnostomum calcareum*, Anomobryum filiforme*, Plagiobryum zieri*, Mnium stellare* and Campylium chrysophyllum*. Dicranella rufescens was found by Sandy Loch after descending from the Glen and Amblystegium juratzkanum was collected near the Pier.

On 4 September some dune areas were investigated. Sandside Bay and Dingieshowe, on the eastern side of the 'Mainland', proved disappointing although Dingieshowe yielded Bryum argenteum var. lanatum*. The dunes near Bow, on the island of Burray were better. Here we found Leiocolea badensis*, L. muelleri, Preissia quadrata, Distichium inclinatum, Amblyodon dealbatus* and Camptothecium lutescens. Marshy ground to the north of the dunes added Cratoneuron commutatum var. falcatum and Philonotis calcarea, while along the shore Eucladium verticillatum and Amblystegium serpens var. salinum were seen.

A second visit to Hoy was made on 5 September. Half the party chose to explore Berrie Dale, a deep ravine having at its lower end the only natural stand of trees on the island. The remaining members went to look at ground in the region of the Kame of Hoy, to the north. The long trek from the Pier was made by way of the Old Rackwick Road, a mere track rendered more like a watercourse by the recent heavy rains. Confirmation of a record for Hedwigia ciliata was sought along the 'road' but in vain, the only bryophyte of interest seen being Tetraplodon mnioides.

The trees of Berrie Dale, mostly birch, yielded little besides Ulota crispa and the ubiquitous U. phyllantha. The stream normally a mere trickle, was so swollen that crossing it was difficult, even hazardous, so that only the lowest portion of the ravine was workable. Having done what they could, the thwarted Berrie Dale contingent climbed the hillside and crossed the stream above the ravine in order to work down to Rackwick. On the moorland Tetraplodon mnioides was seen again, also some patches of Campylopus brevipilus. Mylia taylori, Bazzania trilobata, B. tricrenata and Lepidozia pinnata were some of the species seen growing on the grassy slopes of Grut Fea. This was an unusual habitat for Lepidozia pinnata. The five miles back to the Pier were made, by arrangement, in the van of an obliging farmer, who then picked up the rest of the party as they were trudging back to the boat.

6 September. The valley bog of Glims Moss was chosen for the last day. The Moss was for the most part unremarkable. Among the many species of Sphagnum noted was a great deal of S. magellanicum. Riccardia palmata grew on the sides of a runnel and where almost unrelieved Sphagnum species gave way to rather more interesting conditions, Leiocolea bantriensis and Calypogeia sphagnicola* were found. After lunch we tried our luck on the Dee of Durkadale, a fen area two miles north of Glims Moss. Here we found Trichocolea tomentella* in abundance, Acrocladium giganteum, Mnium rugicum* and M. seligeri*. A short visit was then made to a marshy place near a small lake at Greenay. Scorpidium scorpioides was dominant here and Pottia davalliana* was found on a nearby track.

It was interesting to note that although several crop fields were searched during the meeting they were found to be virtually devoid of bryophytes.

We are grateful to Mrs A. Thomson, who acted as Local Secretary and to Miss E. R. Bullard who, although not a bryologist, came with us every day and contributed much valuable topographical knowledge and advice.

J. APPLEYARD

Annual Meeting 1974

Exeter, 19-20 October

The annual meeting was held on the weekend of 19-20 October in the Department of Biological Sciences at the University of Exeter, by kind permission of Professor J. Webster. About 50 members attended and on the first day heard a series of six lectures on the general theme of water relations in bryophytes.

Dr D. J. READ: 'Physiological aspects of drought resistance in bryophytes'.

Factors contributing to the drought resistance of higher plants and bryophytes were compared and contrasted. Small cell size, small vacuoles, as well as high osmotic content and dense cytoplasm were features associated with resistant cells of higher plants. Although any of these factors might contribute to resistance in bryophytes by lessening the protoplasmic contraction which causes cell damage, they cannot fully explain it, either independently or in combination. Differences in protoplasmic tolerance of dehydration must be the basic cause of different levels of desiccation resistance in bryophytes. Membranes of resistant hepatics appear to have a higher phospho-lipid content than those of susceptible forms and this may confer greater protoplast stability under stress.

The importance of the rate of water loss from a shoot in determining survival was discussed. It was suggested that in many cases the speed with which desiccation occurred was more important to subsequent physiological activity than the absolute level of vapour pressure deficit to which shoots were subjected.

Mr J. W. BATES: 'Sodium uptake and loss in halophytic and glycophytic mosses'.

Total digest data for the halophyte Grimmia maritima collected from seashore habitats suggest that it is a 'salt-tolerator' since it contains large amounts of sodium; but most of this seems to be extracellular. The intracellular sodium content of G. maritima from an exposed seashore site (18µg/g air-dry moss) closely resembles that of the glycophyte G. pulvinata from an inland habitat (17µg/g air-dry moss) indicating that the former species is a 'salt- avoider'.

Treatment with artificial seawater solutions led to a marked net uptake of sodium and net loss of potassium from the intracellular fraction in G. pulvinata, but not in G. maritima. With increased calcium concentration the net uptake of sodium into the intracellular fraction was reduced in G. maritima but increased in G. pulvinata. Calcium may have the effect of decreasing the permeability of the cell membrane to other ions. Sodium uptake may be affected by light, external magnesium concentration and the state of hydration of the moss.

Active uptake and loss of sodium were investigated using metabolic inhibitors. Evidence suggests that gametophytes of G. pulvinata have an active sodium uptake mechanism whereas those of G. maritima have an active sodium efflux mechanism.

Dr G. R. STEWART and Dr J. A. LEE: 'The effects of water stress on membrane properties'.

A number of different ultrastructural and molecular models for the structure of cell walls were described and an attempt was made to reconcile the known response of bryophytes to variations of water stress with these models.

Mr N. J. COL.L.INS: 'Photosynthetic activity of tundra mosses as affected by water content, temperature and radiation'.

An extensive vegetation dominated by cryptogams has developed at some localities in the maritime Antarctic. In many mosses clear innate markers of seasonal growth are present so that the new growth, and hence net annual production, may be recognized easily. Two contrasting communities have been studied in the field at Signy Island, South Orkney Islands, one dominated by turf-forming mosses and the other by carpet-forming mosses. Net annual dry matter production for turf-forming mosses was 340-660 g/m² (this value does not allow for translocation). Translocation is probably insignificant in carpet-forming species so net annual production can be more accurately stated as 220-890 g/m²

The turf-former Polytrichum alpestre experiences temperatures between -5 and +5°C for 80% of the summer; those for the carpet-former Drepanocladus uncinatus are slightly lower. Radiant flux density levels are extremely low for the period from 1800 hrs to 0559 hrs here.

Grown under a temperature regime similar to that experienced in the field, P. alpestre has a temperature optimum for net photosynthesis of about +5°C, while D. uncinatus has an optimum of +15°C. At higher temperatures the optimum for D. uncinatus remains the same, but in P. alpestre it is +15°C. Field water content appears non-limiting to photosynthesis at some sites since the mosses were consistently at or above the water content necessary to maintain maximal rates of net photosynthesis,

Carbon fixation, computed from the combination of the 'cold' response curves for P. alpestre with the micro-climate data, amounts to 315 gC/m² in a 120 day season; when the 'hot' curves are used carbon fixation amounts to nearer 1000 gC/m² in a 120 day season. There is reasonable correspondence with values for dry matter production.

With a broad response curve allowing net carbon fixation over most of the temperature regime, D. uncinatus is well adapted to the oceanic climate of Signy Island. With its ability to acclimatise to changed temperatures over a period of at most 15 days, P. alpestre may be able to utilise periods of high temperatures more efficiently.

Mrs G. MORTON: 'The spatial arrangement of chalk grassland bryophytes with respect to their water relations'.

The objective of this work is to propose an ecological basis from which management plans for chalk grassland nature reserves can be devised, taking account of the bryophyte component. The study site at Aston Rowant National Nature Reserve in the Chilterns has a range of aspects under one treatment, and for one aspect a range of management treatments.

Data analysis by an ordination technique showed stand aspect to be the major source of variation in species composition. Solar radiation, amplified by wind incidence, creates the mesic/xeric gradient found. Management had a modifying influence on the effect of aspect. Increasing biomass caused by winter grazing or by lack of grazing modifies the microclimate, allowing the establishment of species typical of more mesic aspects.

The proportion of rainy days governs the growth of Pseudoscleropodium purum suggesting that differences in response to site moisture regime by various species cause the distribution patterns found. Moisture content of moss samples varies considerably with aspect and with the biomass above the moss.

The drought resistance of several species was tested over 90 days - longer than any dry period occurring in the Chilterns. No species died but the production of new growth after 30 days in a mist unit varied considerably between species. Fissidens cristatus, which occurred throughout the site, showed a steady slow production rate throughout the drought. Mnium undulatum, restricted to sheltered northerly aspects, showed great initial vigour which fell sharply to a net loss in production after long droughts.

Species typical of mesic situations have a greater potential growth rate (competitive ability), whereas those of xeric situations can maintain a constant, slow growth rate even after prolonged drought. The distribution of these types is due to modification in local climate by differences in solar radiation and wind caused by aspect, and changes in biomass of the sward.

It may be possible to manipulate grassland microclimate by management so that desired changes in bryophyte constituents can be induced.

Mr T. J. K. DILKS: 'Ecological aspects of desiccation resistance in bryophytes'.

The ability of 17 species of bryophytes to withstand periods of continuous desiccation at known relative humidities in relation to their geographical and ecological distribution, was discussed. Desiccation tolerance was estimated by the length of time before net assimilation (measured on a Warburg respirometer) became negative after up to 24 hours rehydration, by the chlorophyll-a content and percentage survival after 30 days in a glasshouse under mist, and by the chlorophyll-a content after 7 days at 17°C. The resistance to desiccation was also considered in relation to the minimum water content observed in the field, the length of time taken to dry out after rain and the degree of shading indicated by 'fish-eye' photographs. Hookeria lucens was the species most susceptible to low water contents, followed by a group of species of Atlantic distribution, several woodla nd species which grow in the open in the north and west, species of unshaded habitats such as rocks, tree branches and sand dunes, and finally Rhacomitrium and Andreaea species. A series of experiments on intermittent and interrupted desiccation showed that in tolerant or moderately tolerant species (Hylocomium splendens, Rhytidiadelphus loreus, Tortula ruraliformis) short periods (24 hours) of desiccation each week had little effect on subsequent assimilation or growth, and that a moist period of 24 hours resulted in substantially complete recovery from the effects of a preceding dry period of 6 to 11 days.

Mr N. J. COLLINS: 'The growth of tundra mosses'.
Mr A. C. CRUNDWELL and
Dr H. L. K. WHITEHOUSE:
'Tortula amplexa and T. bolanderi in pure culture from European sources'.
Mr M. V. FLETCHER: 'More mosses from New Zealand'.
Mrs G. MORTON: 'Growth of Pseudoscleropodium purum monitored photographically'.
Dr M. C. F. PROCTOR: 'Hemispherical photography as a tool for studying the light climate'.
'Scanning electron micrographs of bryophytes'.
Dr H. L. K. WHITEHOUSE: 'Ditrichum pusillum in arable fields'.

G. C. S. CLARKE

Field Meeting, South Devon

The localities visited on the excursion on 20 October were all in v.-c. 3. The first site was Chudleigh Rocks, which is a short stretch of steep wooded valley on Devonian limestone with oak, ash, Tilia cordata, etc. Leptodon smithii, Metzgeria fruticulosa and Cololejeunea minutissima occurred as epiphytes; Pleurochaete squarrosa, Trichostomum sinuosum, Riccia sorocarpa, Weissia longifolia var. longifolia and Tortula intermedia were on exposed limestone rocks; and Cololejeunea rossettiana, Lejeunea lamacerina var. azorica, Marchesinia mackaii, Isothecium striatulum, Cinclidotus mucronatus and Isopterygium depressum were on damp shaded limestone rocks. The second site was a wooded stretch of the valley of the River Bovey, partly on granite and partly on metamorphosed Culm Measures, part of the site being within the Yarner Wood National Nature Reserve. Bryum flaccidum* was on an old stone bridge, Porella pinnata on large boulders in the river and Solenostoma triste on shaded rocks on the bank. The trees along the west side of the river sported a number of epiphytes such as Hypnum cupressiforme var. mamillatum, Lejeunea ulicina, Radula complanata and Neckera pumila. On the rocky bank alongside the footpath were Bazzania trilobata, Plagiochila spinulosa and Trichocolea tomentella, while Schistostega pennata was found in shady recesses and Heterocladium heteropterum var. heteropterum on boulders. On the east side of the river Hedwigia ciliata was plentiful on rock faces and boulders.

* = New vice-county record.

Our thanks go to Dr M. C. F. Proctor for organising and leading the trip, and the Nature Conservancy Council and the Warden of Yarner Wood for giving us permission to visit the last site.

T. J. K. DILKS


Taxonomic Workshop 1974

Woolwich, 16-17 November

The Society's first meeting devoted to taxonomic studies took place on 16 November in the School of Biological Sciences of Thames Polytechnic, London, by kind permission of Mr M. D. Morisetti. We thank Dr Paddy Coker for so expertly making the local arrangements. The meeting, attended by 28 members and guests, was intended to be of assistance to beginners in teaching them something about the practical side of naming bryophytes under the microscope. Talks by experts were followed by question and answer sessions and practical indentification of material (participants had been invited to bring along some of their 'problem' specimens).

The meeting was opened by Dr G. C. S. Clarke who introduced the first speaker. Mr A. C. Crundwell on Bryum gave hints on the preparation of material for microscopical study and pointed out some of the problems of identification in the genus, e.g. hybridity. Material collected should be of good quality and if possible bear ripe but not decayed sporophytes. Several species - B. salinum, B. pendulum, B. caespiticium, B. intermedium and B. inclinatum - are indistinguishable sterile. Members of the 'erythrocarpum' and bicolor complexes are unidentifiable without tubers or gemmae.

Dr E. W. Jones reviewed the species of Cephaloziella and of Cephalozia in Britain and showed that although many of the species were easily recognized there were certain groups that often give trouble, e.g. Cephaloziella rubella / hampeana / starkei and Cephalozia ambigua / bicuspidata / lammersiana. He pointed out the importance of sexual structures in identification.

The afternoon session was opened by Dr A. J. E. Smith who gave the results of his recent study of British Ulota species, to be published in a forthcoming paper. He also gave a conspectus of classification of the genus Grimmia in Britain and listed the errors in Grimmia in Dixon's Handbook (especially in the key+).

+ Because of the deficiencies in Dixon's key Dr Smith has prepared keys to the Grimmiaceae which are published in this Bulletin.

Mr A. R. Perry showed how the characters used in the identification of Scapania species might best be observed and discussed the importance of lobe decurrence as a key character. He doubted that S. scandica, S. curta and S. mucronata could be separated in the absence of perianths. A key to British species, adapted from Buch, was handed out.

The majority of those attending the Taxonomic Teach-in joined a field meeting of the London Natural History Society on 17 November by kind invitation of the leader, Mr E. C. Wallace.

The meeting was at Coombe Bottom, Surrey, v.-c. 17. This is a Site of Special Scientific Interest, a woodland area on the scarp slope of the North Downs, the highest part capped with the gravelly Netley Heath deposits. Among the species seen on wood were Dicranum strictum, Bryum flaccidum, Nowellia curvifolia and Plagiothecium curvifolium. Broken pieces of chalk gave us Rhynchostegiella tenella, Fissidens minutulus var. tenuifolius, Tortella inflexa, Seligeria paucifolia and a little S. calcarea. On cleared ground Phascum cuspidatum, Pottia recta, P. truncata and P. intermedia were fruiting well.

In the afternoon we moved a little further west along the escarpment for other terrestrial species. Eurhynchium schleicheri was on loamy soil by the Silent Pool and on the slopes above we saw many typical calcicoles including Brachythecium glareosum, Entodon concinnus, Leiocolea turbinata, Ditrichum flexicaule and Encalypta streptocarpa. We are grateful to Mr Wallace for the interesting finale to a very successful weekend.

I am grateful to Mrs J. E. Smith for preparing the account of the field meeting.

A. R. PERRY

 
 
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