The campus of Bishop Otter College in Chichester was the setting for this year’s AGM and symposium meeting. Thanks are due to Rod Stern for his efforts in securing the venue and ensuring the smooth running of the weekend. It was something of an occasion, as we celebrated the 80th birthday of Dr Harold Whitehouse with a special dinner and cake on the Saturday evening. It was also delightful to be able to welcome members of Harold’s family to the event. We had fine weather for the Sunday field excursion and a good time was had by all.
Dr Mark Hill & Dr Chris Preston (Institute of Terrestrial Ecology, Monks Wood): Bryophytes of Britain and Ireland: local distributions and world ranges
The bryophyte flora of the British Isles comprises about 1023 species, of which 17 are endemic and 19 are introduced. This is 66% of the European total and 6% of the world total. The pteridophytes, by contrast, are a mainly tropical group, with 10,000 species worldwide. A relatively small number occur in Europe, of which 50% occur in Britain and Ireland; these are only 0.7% of the world total. The flowering-plant flora of Britain and Ireland is 14% of the European total and 0.6% of the world total.
Bryophyte distributions are characteristically large and often show wide disjunctions. Metzgeria leptoneura, for example, occurs widely on tropical mountains and in humid parts of the Southern Hemisphere. It is also found in high-rainfall mountains of the Northern Hemisphere. Characterisation of such enormous distributions presents difficulties. Following a scheme devised by us for flowering plants (Preston & Hill, 1997), we have assigned bryophytes to floristic elements on the basis of their patterns of occurrence in the non-tropical Northern Hemisphere, especially western Eurasia.
Latitudinal and altitudinal preferences are specified by qualifiers such as Arctic-montane, Boreal-montane, Temperate and Mediterranean. Longitudinal limits are indicated by qualifiers such as Oceanic, Euro-Siberian and Circumpolar. For bryophytes, an extra longitudinal category, Hyperoceanic, has been added to those used for flowering plants. It applies to species whose distributions are western within the Atlantic zone of Europe.
Distributions within the British Isles generally reflect broader world distributions. Thus Arctic-montane species are concentrated in the higher Scottish mountains, Oceanic Boreal-montane species are concentrated in the wettest parts of north-west Britain and western Ireland, and Mediterranean-Atlantic species are concentrated in south-west England. Temperate bryophytes show few marked trends within the British Isles. They are no more numerous than Boreal-montane bryophytes; this is a marked contrast to the vascular plants, among which the Temperate species outnumber the Boreal-montane by more than five to one.
According to Schuster (1983), Europe’s oceanic bryophytes can be divided into two distinct categories, one originating from the tropics and Southern Hemisphere, the other indigenous to the Northern Hemisphere and showing a pattern which he calls ‘disjunct Laurasian’. This division generally works well, but there are some exceptions, notably Metzgeria leptoneura, whose distribution has attributes of both categories.
Preston CD, Hill MO. 1997. The geographical relationships of British and Irish vascular plants. Botanical Journal of the Linnean Society 124: 1-120.
Schuster RM. 1983. Phytogeography of the bryophytes. In: Schuster RM, ed. New manual of bryology. Nichinan: Hattori Botanical Laboratory, 463-626.
Mr Fred Rumsey (The Natural History Museum, London): Genetic variation in Trichomanes speciosum
The purpose of this talk was twofold: a) to introduce a bryological audience to an overlooked organism, namely the gametophyte generation of the Killarney Fern Trichomanes speciosum, which they are best placed to detect; and b) to look at current patterns of genetic diversity within T. speciosum and attempt to elucidate migration patterns and refugial sites, using this organism as an example of the ‘Atlantic’ element of our flora. This group of mainly bryophyte species includes some of our most interesting taxa, and is of considerable conservation interest at a European, if not global, scale. The history of Atlantic species has been the source of considerable debate, e.g. could taxa with mainly tropical affinities have survived the last glaciation in the British Isles?
Evidence from cpDNA polymorphism indicates that the British Isles supports the greatest genetic diversity, being the meeting point of at least two separate paths of recolonisation from refugia further south. The current genetic diversity of T. speciosum in several possible refugial areas (the Macaronesian enclave near Algeciras, southern Spain; the Alpi Apuane, northern Italy; and the sandstone massifs of the Vosges and the Elbsandsteingebirge) was discussed. All still support nationally significant Atlantic bryophyte elements and almost certainly acted as refugial areas. The possibility remains that south-western Ireland may have maintained certain Atlantic elements throughout the last glaciation but further work is needed to support this. We are now keen to extend this study to include a range of bryophytes, e.g. Dumortiera hirsuta, Cyclodictyon laetevirens and Plagiochila spp., so that we may compare their patterns of genetic diversity with those of the fern element, e.g. Dryopteris aemula, Hymenophyllum tunbrigense, H. wilsonii and T. speciosum.
Mr Malcolm C. Watling (Margate, Kent): Bryology in Kent since Trudy Side
Trudy Side’s Bryophyte Atlas of Kent was published in 1970 by the Kent Field Club (KFC), the county’s natural history society. It was my privilege to have been introduced to the Club and the BBS by Trudy herself. Our correspondence began in 1986 when I studied the bryophytes for a survey of the flora and fauna of the local district, the Isle of Thanet. After Trudy’s death in 1988, I continued my interest and joined the Society in 1990. The following year, Roy Hurr and I became the recorders for the two Kent vice-counties.
At this time, Roy started the South-east Area Group meetings, some 25 of which have been held in Kent to date. A handful of the meetings of the KFC have also been devoted to bryophyte studies. The ‘active bryologists’ of Kent are widely distributed, with a significant cluster around Orpington, where there is a keen local Field Club. Most of us are members of the KFC and the BBS; our meetings and individual efforts have produced some interesting finds:
New records for vice-county 16 (West Kent)
Platygyrium repens: Basset’s Wood (Howard Matcham & Jeff Duckett, 1995).
Nowellia curvifolia: Friezeland Wood (Sylvia Priestley, KFC, 1996).
New records for vice-county 15 (East Kent)
Zygodon conoideus: Kearnsey, Dover (MCW, 1990).
Weissia condensa (W. tortilis): Langdon Cliffs, Dover (MCW, 1990) (first record for over 50 years).
Pottia commutata (now subsumed within Microbryum davallianum): Botany Bay, Broadstair (MCW, 1992).
- starkeana ssp. minutula (now subsumed within Microbryum davallianum): Gorsely Wood, Canterbury (MCW, 1993).
Hennediella (Hyophila) stanfordensis: Ramsgate (MCW, 1993).
Tortula vahliana: Ramsgate (MCW, 1993).
Other interesting records
Warnstorfia (Drepanocladus) fluitans and D. aduncus: new 10 km square records near Crayford (KFC, 1990).
Scorpiurium circinatum: the colony at Hythe revisited (KFC, 1990).
Racomitrium fasciculare: second record for Kent at Ightham Mote (Roy Hurr, BBS, 1990).
Atrichum tenellum and A. angustatum: Combwell Wood (Francis Rose, KFC, 1990).
Mnium stellare and Orthotrichum lyellii: new 10 km square records at Loose, Maidstone (MCW, BBS, 1994).
Hennediella macrophylla (Tortula brevis) and Pohlia camptotrachela: Beacon Country Park (Jeff Duckett & Roy Hurr, BBS, 1995).
Atrichum angustatum: refind of old record at Kingswood, Maidstone (MCW, BBS, 1996).
All of the VC 15 records except the Pottia starkeana have since been found in other places locally. Zygodon conoideus has proved to be widespread but scarce, with seven records so far.
The county of Kent is divided geologically, with chalk to the north and the Weald/Romney Marsh to the south, but the bryologically more significant division is from east to west. The climate becomes considerably drier to the east, greatly reducing the range and abundance of species. Nevertheless, the theory that the distribution of bryophytes reflects the distribution of bryologists seems to be supported by my experience at the extreme eastern end of the county. In areas of coastal semi-natural and man-made habitats, scarcely worthy of a bryological meeting, there are occasional small suitable niches which the local resident can explore in his spare moments! The following have recent new 10 km square records in the far east of Kent: Riccia fluitans, Didymodon umbrosus (Trichostomopsis umbrosa), Pterygoneurum ovatum, Tortula acaulon var. pilifera (Phascum cuspidatum var. piliferum), Plagiomnium cuspidatum, Leskea polycarpa, Campylium stellatum var. protensum, Amblystegium tenax, Brachythecium mildeanum, Eurhynchium speciosum and even, in Thanet, Atrichum undulatum, Mnium hornum and Rhytidiadelphus squarrosus.
My own copy of Trudy Side’s Atlas is annotated with new records showing eastward extensions of the ranges of several fairly widespread species, notably Pseudocrossidium revolutum (Barbula revoluta), P. hornschuchianum (B. hornschuchiana), Didymodon luridus (B. trifaria), Plagiomnium affine and Eurhynchium pumilum. This Atlas is currently being updated and revised by members of the Kent Field Club, with tetrad rather than 10 km square maps.
The Thanet bryophyte atlas resulting from the 1986-7 survey is based on 1 km squares and covers the corner of Kent containing the resorts of Margate, Broadstairs and Ramsgate (an area of nearly two 10 km squares). Comparison of this and the Kent Atlas shows useful local detail, especially in habitats like rivers and woods, which are scarce here.
Thus, the already extensive knowledge of Kent bryophytes has been steadily added to by those of us recording here. With another full season of meetings planned, this seems likely to continue.
Professor Jeffrey G. Duckett (Queen Mary & Westfield College, London), Howard W. Matcham (Chichester, Sussex) & Dr Terry A. Hedderson (University of Reading): Protonemata, propagules, peristomes and phylogeny
Whereas in recent years the vast majority of experimental studies on moss protonemata have focused on elucidating developmental phenomena, such as the cytoskeletal basis of tip growth, graviperception and side branch formation, and have been almost totally restricted to three taxa (Funaria hygrometrica, Aphanorhegma (Physcomitrella) patens and Ceratodon purpureus) grown in axenic cultures, we have accumulated comparative data on both wild and cultured protonemata of over 200 mosses. These encompass all the major groups from Sphagnum, Andreaea and the Polytrichales through the Eubryales from the Archidiales to the Hypnobryales. This body of new information permits for the first time the exploration of the following major questions: Do protonemal features shed any new light on the classification and phylogeny of mosses? If so, are protonemal features congruent with other forms of data? How far on the one hand do protonemal characteristics reinforce traditional classifications based on peristomes, and on the other how far do they support new information from molecular biology?
This novel synthesis of protonemal and molecular data, the latter comprising nucleic acid sequences for nuclear-encoded 18s RNA and the gene rps 4 plus the chloroplast encoded gene ter L-F spacer region, is a particularly apposite tribute to Harold Whitehouse. He is both a most distinguished geneticist and the only person to have previously gathered comparative information on gemmiferous protonemata (Whitehouse, 1987). It is his indomitable enthusiasm for things difficult to find in unprepossessing places that has led many of the members of the BBS, including one of us (JGD), on the downwards path to arabology.
Apart from the reassignment of Takakia from the liverworts to the Andreaeopsida (Renzaglia, McFarland & Smith, 1997), current classifications of mosses, apart from what might be described as ‘minor tinkering’ with orders and families, are much the same as those of the nineteenth century. The isolated position of Sphagnum, originally based on traditional morphological criteria, has been reinforced in more recent times by new data on features like spermatozoid ultrastructure (Renzaglia & Duckett, 1988), the gametophyte/sporophyte junction (Ligrone, Duckett & Renzaglia, 1993), and its unique mode of stem elongation involving both apical and subapical meristems (Ligrone & Duckett, 1998). Its thalloid protonema, with bud formation and responses to growth regulators very different from all other mosses, further separates Sphagnum from all other mosses (Goode, Stead & Duckett, 1992).
The only other group of mosses lacking typical protonemata and rhizoids (defined as tip-growing uniaxial filaments with new cells being added by division of the apical cell or laterally via side branch initials) are the Andreaeopsida. The juvenile stages in both Takakia and Andreaea comprise ill-defined, sometimes multiaxial, axial to almost parenchymatous ‘filaments’ which are difficult to equate with the highly ordered protonemata and rhizoids of other mosses. Indeed, these juvenile stages more closely resemble the filamentous structures produced by the germinating spores of a few jungermannialean liverworts, e.g. Cephalozia. Even the so-called rhizoidless mosses (Calliergon trifarium, Pleurozium, Pseudoscleropodium, Rhytidium, Hylocomium, Scorpidium) always produce typical protonemata from spores and from rhizoids during regeneration in culture from gametophyte fragments.
Apart from Sphagnum, the only other well-documented non-filamentous protonemal structures are the plates in the Tetraphidales (Goode, Duckett & Stead, 1992) and the funnel-shaped upright appendages in the Buxbaumiales (Duckett, 1994). It therefore came as a considerable surprise to discover Tetraphis-like protonemal plates around colonies of Oedipodium griffithianum. A fossick through the literature revealed a passing mention of these in Goebel (1905) which was then tracked down, via Goebel (1889), to the original and apparently only first-hand description by Berggren (1873), whence they appear to have been forgotten. Culturing of Oedipodium, from both gemmae and spores, confirmed the Tetraphis-like protonema. Oedipodium is almost invariably placed with the Funariales – solely, it seems, on the basis of supposed similarities in capsule shape. However, Oedipodium lacks a peristome, and the quadrifed structure in Tetraphidales cannot be sensibly reconciled with the peristomes of other mosses. Molecular data now place Oedipodium and Tetraphis close together, and far removed from all the Eubryidae. In contrast, three of the four genera in the Gigaspermaceae (Gigaspermum, Oedipodiella, Chamaebryum) which all lack peristomes and are also placed close to the Funariales, all have unremarkable protonemata.
Also striking is the closeness in molecular terms of the Polytrichales and Buxbaumiales. Here again, the protonemata have a notable commonality; buds are produced from the centre of upright parenchyma-like branches, though these are not funnel-shaped in the Polytrichales. We have never seen protonemal gemmae in either group.
Within the Eubryidae examples of remarkable and sometimes totally unexpected congruence are now emerging between molecular and protonemata data. With their highly-structured basal tmema (abscission) cells and attenuated sticky acumina, the protonemal gemmae of Calymperes, Octoblepharum and Syrropodon (Ligrone, Duckett & Egunyomi, 1992) in the Dicranales are the most highly structured yet described in mosses. But very similar gemmae also occur in the supposedly unrelated moss, Schistostega (Edwards, 1978) which, like Oedipodium, is eperistomate. Both molecular data and the protonemal propagules indicate that Schistostega should now be transferred from the Diplolepideae into the Dicranales.
Pointed chloronemata are a characteristic feature of the Pottiales, a few members of the Dicranales, and the supposedly funarialean, but again eperistomate, Ephemerum (Duckett, Goode & Stead, 1993). Molecular data indicate strong affinities between these taxa, and support the transfer of Ephemerum to the Haplolepideae. Schizolytic separation of protonemal foliar and cauline gemmae throughout the Pottiales (Ligrone, Duckett & Gambardella, 1996) contrasts with the more widespread liberation mechanism involving tmema cells, and suggests that this is a natural order.
Molecular affinities between the Grimmiaceae and the Ptychomitriaceae are reinforced by similar protonemata, which in both these families comprise attenuated filaments bereft of gemmae. To date the Grimmiales is the only group which does not comply with the ‘Whitehouse Rule’ (Whitehouse, 1987) – mosses that produce protonemal gemmae also produce these elsewhere and vice versa. Short-celled transversely-septate protonemata and molecular data unify the Orthotrichales (Goode, Stead & Duckett, 1993) and Isobryales, whereas hypnobryalean protonemata appear to be singularly uninteresting taxonomically. All have typical funarialean chloro/caulonemata, and gemmae are remarkably rare, two notable exceptions being Pseudotaxiphyllum (Isopterygium) elegans and Eurhynchium hians (E. swartzii). In the latter species their occurrence could well explain the arcane occurrence of these rarely-fruiting mosses in transient habitats.
The new data from molecular biology and protonemata suggest major revisions will be needed for future moss Floras.
Berggren S. 1873. Om proembryots utveckling och byggnad hos slägtena Diphyscium och Oedipodium. Botaniska Notiser 109-112.
Duckett JG. 1994. Studies of protonemal morphogenesis in mosses. V. Diphyscium foliosum (Hedw.) Mohr (Buxbaumiales). Journal of Bryology 18: 223-238.
Duckett JG, Goode JA, Stead AD. 1993. Studies of protonemal morphogenesis in mosses. I. Ephemerum. Journal of Bryology 17: 397-408.
Edwards SR. 1978. Protonemal gemmae in Schistostega pennata (Hedw.) Web. et Mohr. Journal of Bryology 10: 69-72.
Goebel K. 1889. Ueber die Jugendzustände der Pflanzen. Flora 72: 1-45.
Goebel K. 1905. Organography of plants. Translated IB Balfour. Oxford: Oxford University Press.
Goode JA, Duckett JG, Stead AD. 1992. Morphogenesis of the moss Tetraphis pellucida Hedw. in culture and in the wild. Annals of Botany 70: 519-530.
Goode, JA, Stead AD, Duckett JG. 1993. Studies of protonemal morphogenesis in mosses. II. Orthotrichum obtusifolium Brid. Journal of Bryology 17: 409-419.
Ligrone R, Duckett JG, Egunyomi A. 1992. Foliar and protonemal gemmae in the tropical moss Calymperes (Calymperaceae): an ultrastructural study. Cryptogamic Botany 2: 317-329.
Ligrone R, Duckett JG, Renzaglia KS. 1993. The gametophyte-sporophyte junction in land plants. Advances in Botanical Research 19: 231-317.
Ligrone R, Duckett JG, Gambardella R. 1996. Serial development of foliar gemmae in Tortula (Pottiales, Musci), an ultrastructural study. Annals of Botany 78: 305-315.
Ligrone R, Duckett JG. 1998. Development of the leafy shoot in Sphagnum (Bryophyta) involves the activity of both apical and subapical meristems. New Phytologist 140: 581-596.
Renzaglia KS, Duckett JG. 1988. Different developmental processes underlie spermatozoid architecture in mosses, hepatics and hornworts. Journal of the Hattori Botanical Laboratory 64: 219-235.
Renzaglia KS, McFarland FD, Smith DK. 1997. Anatomy and ultrastructure of the sporophyte of Takakia ceratophylla (Bryophyta). American Journal of Botany 84: 1337-1350.
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Field excursion to Didling Hill, Chalkpit Lane and Midhurst Common, 14 September 1997
In the morning, 36 members explored the steep north-facing slope of Didling Hill, including chalk grassland and semi-natural mixed broadleaved woodland. The banks of the track through the woodland had Eurhynchium schleicheri and there were plenty of chalk stones with Seligeria calycina (S. paucifolia) c.fr. and Tortella inflexa. All the more interesting chalk grassland liverworts known from this site were refound, including Frullania tamarisci, Scapania aspera (locally abundant), Porella arboris-vitae and Jungermannia atrovirens. We failed to refind the mosses Racomitrium lanuginosum and Antitrichia curtipendula from the top of the hill, in spite of careful searching led by Francis Rose, who knew these from the site previously. A good colony of Hylocomium brevirostre, not seen before at Didling, was some compensation. A remarkable find was a patch of Aulacomnium palustre on steep chalk grassland (the pH of this was determined by David Streeter as 8.4).
After lunch, a visit was made to Chalkpit Lane near the Trundle from where there is a fine view over the West Sussex coastal plain, Chichester Harbour and the Isle of Wight. Thuidium abietinum ssp. abietinum and ssp. hystricosum were seen growing near each other in the only extant locality for both on the South Downs. The excursion finished by Midhurst Common in an old brick pit where Lophocolea bispinosa (first found there by Howard Matcham a few years ago) is still abundant. Fossombronia foveolata and Blasia pusilla were also seen there.