The autumn weekend meeting was held on 22-23 October in the University of Manchester’s Robert Robinson Building by kind permission of Professor D. H. Valentine.
Papers were read on the Saturday morning and afternoon. The President, Mrs J. Appleyard, introduced the speakers. Summaries of the papers are given below.
Dr A. J. E. Smith: ‘Chromosome studies on mosses.’
The techniques used in moss cytology were described and the use of and types of problem raised by the study of moss chromosomes, with particular reference to British material, was commented on.
Mr R. L. A. Oliver: ‘Studies on bryophyte colonization of Tentsmuir Dunes.’
In the older fixed dunes ‘mat’ and ‘weft’ type mosses were dominant, though rare or absent at earlier stages.
Experiments with moss fragments grown on media lacking particular nutrients were inconclusive. Rhizoids were produced on all media by all species investigated, but growth was greatest on those without nitrogen, perhaps the effect of the addition of sulphates which were used to replace nitrates.
Experiments on the effect of temperature on rhizoid production and on recovery after desiccation were also described.
Dr S. W. Greene: ‘Reproductive behaviour in mosses.’
The suggestion has been made recently that in perennial mosses, and perhaps also in many annuals, reproduction is almost entirely other than by spores and that abandonment of sexuality may be an important factor in the slow evolution of mosses. However, evidence was presented from studies on the British moss flora which showed that over 60% of the species frequently produced fruit and that of this number monoecious species were more frequently found in fruit than dioecious species. Frequency of fruit in the former group has been attributed to regular inbreeding but evidence on the nature of the colony is essential before this can be accepted as the general rule. In some Orthotricha, for example, it was shown that the colony was a population rather than a clone and so normal outbreeding between individuals could have taken place. For dioecious species, evidence is accumulating that most populations are unisexual with female colonies outnumbering male colonies; however, when bisexual colonies occur fruit is regularly formed. From this and other evidence it was concluded that, far from being abandoned, sexual reproduction is regularly successfully achieved by many species of the British moss flora.
Mr G. C. E. Argent: ‘Gathering moss in the Cameroons.’
A visit was made in October and November 1965 to Western Cameroun (formerly part of British Cameroons) for the purpose of collecting mosses. This time of year was chosen because it coincides with the transition from rainy to dry seasons when the roads are open but the vegetation is not too dry.
Collections were made in the depleted lowland rain forest and plantations around Kumba, where a number of interesting plants such as Jaegerina cameruniae (Broth.) Wijk & Marg. were found in abundance, although generally the moss flora was poor. Collections were also made in the region of Cameroons Mountain where the moss flora was much richer. Montane rain forest occurs up to 6000 ft., which besides having a high rainfall is enveloped in mist for long periods and this habitat provided an abundance of epiphytes. Above this occurs grassland where Hedwigia integrifolia P. Beauv. was a common species and near the summit at over 13,000 ft. was an open community consisting largely of mosses, including such genera as Leptodontium, Rhacomitrium and Polytrichum.
Much of the collection brought back still remains to be identified and many taxonomic problems arise in a region where the plants are still very poorly known.
Dr W. S. Lacey: ‘Geological history of the Bryophytes.’
An account of authenticated fossil records for the major bryophyte groups was given. The earliest liverworts, such as Hepaticites devonicus from the Upper Devonian, are unfortunately sterile and difficult to classify. They have been referred on vegetative characters to Jungermanniales Anacrogynae. The Acrogynae are not found until the early Tertiary. A hepatic from the early mesozoic, Naiadita for which archegonia and sporophyte are known, has been placed in the Sphaerocarpales. The Sphagnales are first represented by Protosphagnum, described by Neuberg from the Permian of the U.S.S.R. This genus has groups of hyaline cells in the leaf, which is nerved. The same author has described the earliest Bryidae, also from the Permian of the U.S.S.R., including Intia which has leaves resembling those of Bryum or Mnium. Other groups completely lack a fossil history, such as Andreaea, first found in Quaternary deposits. In addition there are some problematical fossils which may well be bryophytes, for example Sporogonites, Protosalvinia, Sporogonium and Tetrapterites.
In the absence of a fossil record for more than a few groups of bryophytes, phylogenetic speculation is of doubtful value.
Mr D. F. Chamberlain: ‘Taxonomy of Pottia.’
The application of biometrics to the taxonomy of Pottia davalliana, P. starkeana and P. commutata was discussed, including related non-British species.
After the papers the President thanked the speakers. A special General Meeting was held.
In the evening the conversazione was held in the Robert Robinson Building and the following exhibits were on display:
|Mr G. C. E. ARGENT:||African Mosses.|
|Miss F. G. BELL:||Sub-fossil mosses from a last glaciation site in Hunts.|
|Mr and Mrs H. J. B. BIRKS:||Grimmia agassizii in Britain. The Epiphytic Communities of the Lizard, Cornwall.|
|Dr J. H. DICKSON:||Colonizers of the 1961 volcano on Tristan da Cunha. Pseudoscleropodium on St Helena. Cryptothallus in Wales.|
|Dr W. S. LACEY:||Fossil bryophytes, real and conjectural.|
|Dr A.J.E.SMITH:||Cytotaxonomy of Tortula muralis. The B.B.S. mapping scheme.|
On the Sunday about twenty members turned out on a showery day to visit three or four localities. The first was Plumley lime beds, a Cheshire Conservation Trust Nature Reserve. The lime waste and the path around it produced a large number of small acrocarpous mosses, including many species of Barbula and several of Bryum. Bryum bicolor was seen in two forms with large and with small bulbils. The interesting find of Desmatodon cernuus* on the path to the lime beds was made. Some members went on to Witton lime beds where they saw Moerckia flotoviana, recently discovered there. Leiocolea badensis was also seen.
[* new v.-c. record]
A contrasting habitat was afforded by Abbots Moss, also a Cheshire Conservation Trust Nature Reserve, where an extremely wet bog basin and surrounding heath and pine plantation were visited. At Oakmere, the next locality visited, a lake margin and heath and woodland provided some interesting finds. A. Stirling found Dicranum polysetum* in pine-birch woodland near the north end of the lake and E. Little found Cephaloziella hampeana* in heathy ground adjoining the lake. At the lakeside were Atrichum crispum and Cladopodiella fluitans.
Thanks are due to Dr J. Tallis who arranged the programme.
F. G. Bell