Some 45 members visited Reading for the autumn paper-reading meeting on 24 October 1964. The following summaries are available of the papers read.
Mr G. A. Yarranton: ‘Statistical investigations into the structure and ecology of some saxicolous bryophyte communities at Steps Bridge, Devon.’
A general account of the Steps Bridge area was given. An absolute method of sampling for interspecific association was described and the data so collected demonstrated. A pattern diagram based on X ² values and an ordered correlation matrix dividing the species into six overlapping groups were presented. The application of principal components analysis to the correlation matrix and the resulting ordinations of species and samples were discussed. Correlation of the components with environmental measurements made at the sample points associated the first component with shade and the second with crevice vegetation, but there were insufficient data to decide whether the remaining components can be related to environmental variation.
Dr A. J. E. Smith: ‘Variation in Fissidens minutulus.’
An investigation of about 400 herbarium specimens revealed that there is some intergradation between Fissidens minutulus var. minutulus and var. tenuifolius and that some of the taxonomic characters used to separate the two varieties are invalid. It was also shown that there were two main morphological forms within var. minutulus, one with thin-walled cells and narrow border to the blunt leaves, the other with incrassate cells and a thick border to the more acute leaves. It was considered that a cytogenetic investigation into the taxonomic status of the various forms of the species was required.
Dr P. J. Grubb: ‘Further studies on uptake and movement of mineral ions in Polytrichum formosum Hedw.’
In an earlier report (Trans. Brit. Bryol. Soc. 4, 1961, p. 184) it was concluded that mineral ions are moved passively through the gametophyte and sporophyte in the transpiration stream and that there is no active redistribution such as occurs in the phloem of higher plants. New confirmatory experiments with plants washed out of the soil were reported, showing that movement through the rhizome is passive from weak as well as from strong solutions and that the likelihood of active upward transport in the leptome is negligible. Other experiments showed that, when sods of soil were irrigated with various solutions from below, the shoot contents of sodium and potassium could be affected as though by a passive flux of solution. However, the potassium to sodium ratio in naturally grown shoots is much higher than in the soil so that some factor other than passive supply from below is involved. Very probably much of the potassium supply comes in the rain-leachate from the trees above the moss. Certain data from analyses of growing shoots and sporophytes were presented to show that some redistribution mechanism may be present; a redistribution of organic materials is certainly needed for the growth of the rhizomes through the soil.
Mr A. H. Norkett: ‘A modern concept of the Sections in the genus Fissidens .’
As an interim measure, it is necessary to split a large genus such as Fissidens into a number of smaller units. Mainly as the outcome of proposals made by C. Müller (1901), Fissidens is currently divided into four subgenera, Aneuron, Pachyfissidens, Octodiceras and Fissidens. This last is subdivided into numerous sections. Mr Norkett discussed these Sections, pointing out that many of them were made on the basis of herbarium study only. His own ecological studies on the genus in Asia and subsequent research had provided grounds for a provisional re-arrangement. The result was a recommendation that the Sections of subgenus Fissidens be reduced from twelve to eight; but in several of these Mr Norkett would recognize up to three sub-sections. Of special interest was the new concept given to the Section Crispidium, by which it would contain only those species with ‘water storage glands’ in their leaf axils.
Dr M. C. F. Proctor: ‘Some comments on bryophyte distribution patterns.’
The author’s summary, unfortunately, had not been received at the time of going to press.
Prof. H. Ochi: ‘Preliminary notes on the phylogeny in the family Bryaceae.’
Discussion turned mainly on possible phylogenetic relationships between the genera of the subfamily Bryoideae. Observations had been made on over 120 species. Prof. Ochi considered that in the past capsule characters had been over-emphasized. He drew evidence from gametophytes, distribution patterns, cytology and other sources. Making use of such evidence he concluded: (i) that the genus Plagiobryum was closely related to the sub-section Areodictyon of the genus Bryum; (2) that the section Dicranobryum of the genus Brachymenium was near subsection Bryum (of section Bryum of the genus Bryum); and (3) that section Orthocarpus of Brachymenium was closely related to subsection Rosulata (of the genus Bryum). These were, however, only preliminary suggestions.
General discussion followed the last paper, when numerous questions were put to the various speakers. The President thanked the speakers and Dr Warburg conveyed the thanks of the visiting members to the President who had also acted as local Secretary. Mr James Dickson, as Secretary for autumn paper-reading meetings, had laid the foundations of the programme.
The evening conversazione was held in the Department of Botany where members were the guests of Prof. T. M. Harris, F.R.S., himself a member for many years. The following exhibits were on display:
|Mr G. C. ARGENT:||Bryophytes collected by Prof. P. W. Richards in Africa, Borneo and Sarawak,|
|Mr D. F. CHAMBERLAIN:||Taxonomic problems in the genus Pottia.|
|Miss O. M. CROWSON
and Dr E. V. WATSON:
|Liverworts in the Reading University living collection.|
|Mr JAMES DICKSON:||Funaria hygrometrica new to Tristan da Cunha; and mosses in Bronze Age Boat-building.|
|Mr ALAN HARRINGTON:||Studies of Scapania aspera and S. gracilis.|
|Dr E. W. JONES:||Epiphyllous liverworts.|
|Mr A. H. NORKETT:||Sections of the genus Fissidens.|
|Dr A. J. E. SMITH:||The mapping scheme.|
|Dr E. F. WARBURG:||Pohlia pulchella and Grimmia borealis new to the British Isles.|
|Dr E. V, WATSON:||Some bryophytes from Jan Mayen.|
The local excursion, on Sunday 25 October, was favoured with exceptionally fine, warm weather. About 25 members attended and four localities were visited. All are in the extensive Tertiary heath area that lies south-west of Reading, Gibbet Piece (Mortimer) and Padworth Common being in Berkshire (v.c. 22); Tadley Common and Silchester Common in north Hampshire (v.c. 12). Thus, heathland mainly was searched, but the gully at Padworth and the low-lying parts of Silchester provided interesting habitats in deep shade, on waterlogged clay.
Campylopus brevipilus was plentiful on parts of Gibbet Piece, and C. introflexus was found across the road, in the Pickling Yard (where it has been known for some years). Mrs Paton found Cephaloziella subdentata and C. rubella and Mr E. R. B. Little recorded Lophozia bicrenata, c.per. Mr P. J. Wanstall found a few stems of Dicranum polysetum (new to v.c. 22).
On Padworth Common Dr E. F. Warburg found Pellia neesiana (new; to v.c. 22). Mr R. D. Fitzgerald found Dicranum strictum on a tree just above the gully. Species of Plagiothecium seen included P. denticulatum, P. sylvaticum, P. succulentum and P. curvifolium. Here also was Hypnum cupressiforme var. mamillatum. Leptodontium flexifolium occurred along the drier heathland paths. Other species noticed at Padworth included Chiloscyphus polyanthos, Lejeunea ulicina and Drepanocladus exannulatus.
Tadley offered a less diversified terrain but even what seemed (after the dry summer) to be not very moist heath provided extensive carpets of Campylopus brevipilus (with great variation in colour) and a certain amount of C. introflexus. Locally, amid Calluna, Dicranum spurium was found. Cladopodiella francisci, Cephaloziella starkei, C. subdentata, and on lower-lying ground Acrocladium stramineum occurred.
Silchester Common, however, provided the big excitement of the day when Mr James Dickson, ‘digging’ with uncanny accuracy, turned up Cryptothallus mirabilis, within a few minutes of his arrival. Frantic excavation by others resulted in some more being uncovered. The material included some with young and mature sporophytes and one capsule with ripe spores lay loose in the Molinia leaf litter. Birch grew close at hand. In the valley alder carr at Silchester Dr E. W. Jones found Hookeria lucens (new to v.c. 12) in fruit. Other species seen included Bryum rubens, Pohlia delicatula, Pseudephemerum nitidum, and Tetraphis pellucida which was fruiting freely in places.
A record card taken by Dr A. J. E. Smith included nine species of Sphagnum. Perhaps the most interesting was a ‘papillosum‘ state from Tadley. This had a hint of the dark red of S. magellanicum in its colour and on sectioning the leaves later I found the chlorophyllous cells to be almost centrally placed. The papillosity was clear enough, however, and Miss Lobley had no hesitation in referring it to S. papillosum.
I would conclude by acknowledging the pleasure it gave me to welcome members to Reading, and by thanking all those who by their participation helped to make the meeting a success. Mr Dickson began to lay his plans early and to him I am particularly grateful for his indispensable preparatory work.
E. V. Watson