Suffolk mosses and liverworts

SUFFOLK MOSSES AND LIVERWORTS A . C . SMITH The bryophytes are usually thought of as a difficult group of plants. T h e r e is a sameness a b o u t some of t h e m ; they have no marked features like a flower to put you on the right track; s o m e are small and hard to see, even with a lens; the two main groups - the mosses and liverworts - are not easy to distinguish; they have n o c o m m o n names. You have already to know the plants, it s e e m s ' to ask the questions that will enable you to know them.

W h a t e v e r the truth of this may be, the bryophytes are interesting to naturalists for the problems they raise, even although the plants m e n t i o n e d cannot be visualised. In these notes I want to touch on a few of these Problems; and indicate some of the subjects bryologists talk about.

It is a p p r o p r i a t e to begin with A r t h u r Mayfield's list of Suffolk bryophytes published in 1930. H e r e he recorded 52 species of liverworts, and 219 of mosses, of which 10 were Sphagnum.

Since that time, the British Bryological Society (Corley & Hill, 1981) has published a census catalogue giving the distribution of bryophytes in the British Isles by vice-counties. At the end of 1987, 71 liverworts and 254 mosses of which 13 are Sphagna were recorded for Suffolk. This is out of a total for the British Isles of 287 liverworts and 798 mosses, including 30 of Sphagnum.

B e f o r e c o m p a r i n g these figures, we need to bear in mind s o m e of the changes that have taken place in the list of British species in the last 60 years or so.

The moss Orthodontiam lineare, previously only known from the southern h e m i s p h e r e , was first described from Cheshire in 1922 (Smith, 1978a). Since then it has spread rapidly throughout the country and on the continent. It was recorded in Suffolk in 1951 a n d can now readily be seen on the bases o f t r e e s and on rotting wood. It fruits abundantly and each capsule has been estimated to contain 70,000 spores (Kreulen, 1972). But it should be r e m e m b e r e d that it is habitat that determines the ränge of a plant, not the n u m b e r of spores and the distance they can travel.

A n o t h e r native moss of the southern hemisphere, Campylopus introflexus, was first f o u n d in Sussex in 1951 (Smith, 1978a). It, too, has spread rapidly especially on bare peat, rotting wood and about the bases of trees. It is often very a b u n d a n t , for e x a m p l e , on W o r t h a m Ling. It fruits in Suffolk, but not as abundantly as the previous species.

T h e fruits of mosses are of f u n d a m e n t a l importance in Classification, and generic n a m e s are often derived from some aspect of t h e m . In Campylopus the capsule is raised on a stalk, the seta, which is shaped like a swan's neck.

T h e word m e a n s curved foot.

But it is not only species now widespread and c o m m o n in the country which have arrived in Suffolk. T h e rare moss Trichostomopsis umbrosa, first recorded in H a m p s h i r e in 1958, has, since 1986, become part of the flora of Suffolk. It is a small plant, u p to 1cm tall and produces propagules, called

Trans. Suffolk

Nat. Soc. 25

66

Suffolk Natural History, Vol. 25

gemmae, on the rhizoids which attach the plant to the substrate. Gemmae can be likened to tubers (like potatoes) which assist in the vegetative reproduction of the plant. T. umbrosa occurs mainly in places where there has been some human activity e.g. the base of bridges and churches. (Eckel 1986; Crundwell & Whitehouse, 1978).

A second important influence on our list of bryophytes has been the increase in the number of species as a result of taxonomic revision. For example, the moss which Mayfield recorded as Bryum erythrocarpum has now been shown to consist of 9 distinct taxa of which 8 have been recorded in Suffolk (Crundwell & Nyholm, 1964).

As Watson (1985) has pointed out, 'Bryologists of fifty to sixty years ago could hardly have anticipated that in the 19-year period from the Start of 1964 to the end of 1982 there would appear descriptions of no less than 20 species new to science, all acquisitions for the British bryophyte flora, and including in Pictus scoticus (Townsend, 1982), a representative of an entirely new genus.'

The relatively stable world of bryology in 1930 has given way to one of change.

Of course, many native and widely distributed plants have been found in Suffolk since Mayfield produced his list. Acquisitions to both our vicecounties (25 and 26) are being made every year and are likely to continue, as Suffolk is not well documentated except for the Breckland and the fens of the Little Ouse/Waveney Valley.

However, no list of species can indicate the degree of abundance or scarcity of the plants it contains; nor can it record changes that have taken place in our more important habitats. What is more it cannot teil us whether species recorded, say, 30 years ago can still be found. All this work can only be done by bryologists working regularly in the county. Indeed, it can be said that the problem facing bryologists new to Suffolk is not so much finding new plants, but trying to discover which plants are common or uncommon and whether those recorded years ago still exist.

When the British Bryological Society produces its Atlas of the Bryophytes of the British Isles, we shall have information on each species recorded on 10km squares. But a dot on a Square can indicate only a few plants or abundance in a suitable habitat.

For example, last year a small tuft of the moss, Racomitrium aciculare was found on the wall of a Suffolk church. This plant is common on wet rocks in the north and west of Britain; but it has not previously been found in East Anglia. This is an interesting but not particularly significant discovery. It is otherwise with another moss, not mentioned by Mayfield, Scleropodium cespitans. A small patch was first seen in 1981, on a stone at the entrance to a south Suffolk church; then, in 1986, it was found abundant and fruiting (which this species rarely does) on trees in a wet wood in the north of the county. Of these examples, the last is really significant, the more so as the wood also contains other uncommon plants. When looked upon from the point of view of flowering plants, trees and ferns it is only of passing interest, but as soon as one turns to the bryophytes it becomes fascinating.

It is this imaginative shift which enables habitat to be seen with different Trans. Suffolk Nat. Soc. 25

SUFFOLK MOSSES A N D LIVERWORTS

67

eyes that is one of the greatest contributions bryology can make to natural history.

Now, as most bryophytes are perennials, it is reasonable to assume that many of the plants recorded in the last 60 years have been here for a long time, in suitable habitats. But where these have changed, it is likely that species have been lost or their numbers diminished.

It is instructive to look at a conspicuous group like Sphagnum. Mayfield recorded 4 species from Redgrave Fen and 2 from Hopton Fen. On present knowledge, there is only 1 species in Redgrave and none at all in Hopton.

Bearing in mind that the BBS list contains records made many years ago, it is important to find out what species survive in the county and where they are to befound.

The most likely reason for the decline of Sphagna in the fens is that they are now much drier than formerly. If this is so, the change probably occurred some time after the late 1950s. In 1956 and 1957 Dr. Francis Rose found liverworts like Preissia quadrata, Riccardia latifrons, Moerkia hibernica and Calypogeia sphagnicola in Redgrave. None of these plants has been seen in recent years. They all grow in wet places. So the fate of Sphagnum may be linked to that of other species. Mr. David Strauss has started the work of recording the Sphagna of the county. When this is complete, we will know the present distribution of the genus, and perhaps also that of other species which might grow with it.

Sphagnum is one of two groups of bryophytes which have a common name in use today: the peat mosses. The other is the hepatics, usually called liverworts. Common names, as we all know, can be very misleading. None more so than here. Club mosses are vascular plants of the genus Lycopodium, reindeer moss is a liehen and carageen moss is a marine alga. No moss grows in salt water. In 1811, A Treatise on Moss by William Aiton was published in Scotland. The book, alas, has nothing to do with bryology, although a few bryophytes are mentioned in it. Moss is here used in a wider meaning retained, for example, in Solway Moss and the border terrain over which the moss troopers rode. The book is an exposition on how to convert 'earth moss' from these places into manure. 'Mosses' are much loved by bryologists for their bryophytes, some of which flourish on peat - whether it contains Sphagnum or not. Naturalists visiting these habitats may be comforted to know that Aiton, at length and with some asperity, refuted the belief among 'the lower Orders', that 'mosses' were formed by the deluge, and the trees of Scotland cut down to provide timber for Noah's ark.

It is not only a whole genus of plants, like Sphagnum, that need to be studied. Some individual species require special attention. It seems clear that, in the past, the liverwort Frullania dilatata was common in the county.

Mayfield did not feel the need to mention any special localities for it - just 'On trunks of trees. Common.' This beautiful plant should be looked for by bryologists, for, so far, I have not seen it anywhere in Suffolk.

The leaves of this genus are elaborate and interesting. Part of them is shaped like a small bell or helmet which is tucked behind the main, circular lobes of the leaves. These bell shaped underlobes can trap water, and the little reservoirs are sometimes inhabited by rotifers. This is a remarkable

Trans. Suffolk Nat. Soc. 25

68

Suffolk Natural History, Vol. 25

example of an association between bryophytes and invertebrates (Gerson, 1982). When examining the rhizoids of mosses for gemmae, I have sometimes seen galls attached to them, but I did not know which animals were responsible for them. In one occasion I thought they were gemmae and misnamed the plant.

According to Crum (1983), 'In nature animals rarely eat bryophytes, possibly because of their taste!' They are also relatively free from parasitic micro-organisms ( B a n e r j e e & Sen, 1979). Professor Crum's bryoculinary researches have revealed, for example, that Sphagna have a slightly fishy taste, and that the taste of the Breckland moss Rhodobryum roseum is very unpleasant and long lasting. But human beings are persistent. In 1863 the Reverend M. J . Berkeley wrote that Sphagnum 'is sometimes ground up to eke out a scanty supply of meal, but without a notion as to its possessing any nutritive qualities'.

Many liverworts are aromatic. Their cells contain oil bodies whose size and number can assist in identification, but their fragrance is more appropriate to the perfumery than the kitchen. The large, forked, strap-shaped liverwort, Conocephalum conicum, is unique. The female plant is aromatic; the male is not. T h e female plant has to be crushed slightly before the fragrance can be detected (Suire & Asakawa, 1979). In a feminist age, no more can be said.

Bryophytes are also of interest to ornithologists. Many British birds build their nests with mosses. I do not know if they use other materials if mosses are scarce. Richardson (1981) comments, 'Unfortunately the species of mosses used by birds to build their nests are seldom mentioned in ornithology books, even though some birds are prolific moss collectors'.

The problem of the spread or decline of species can also be tackled by a careful study of other habitats. Mayfield no doubt found many species on Knettishall Heath; but he mentioned it specifically in relation to 10 liverworts and 21 mosses. O f these, only 3 liverworts and 9 mosses have been found on the Heath in the last few years. Some of the other species may still, of course, be found there. Writing in 1932 about the liverworts, Mayfield said, 'of the fifty-two species known to occur in Suffolk the greater number appear to be confined to the bogs and damp heaths in the east and north-west of the county'.

There is no doubt that Mayfield thought of Knettishall as a damp heath. If the number of species there and in the Valley fens have declined as the habitats have dried out, it is possible that other habitats have suffered similar losses in the last few decades. Even a modern list of species, which contains records from the 1950s and before, may not accurately represent the bryophyte flora of today.

In 1984, a small quantity of a rare Suffolk moss, Orthotrichum pulchellum, not seen by Mayfield, was found on the Heath. Many of the species of this genus are highly susceptible to atmospheric pollution and have decreased markedly this Century (Smith, 1978a). It is worth pointing out that many of the early studies of atmospheric pollution were done by bryologists and lichenologists ( R a o , 1982).

An interesting study was made some years ago in Glasgow of the problem of lead pollution on the soil and plants in cities (Briggs, 1972). T h e liverwort

Trans. Suffolk Nat. Soc. 25

SUFFOLK MOSSES A N D LIVERWORTS

69

Marchantia polymorpha was used in this work. One of the conclusions reached was that city populations of Marchantia had developed a greater tolerance to lead than country populations. This indicated that there had been selection in relatively recent times for lead tolerance in populations of Marchantia polymorpha in polluted areas (Smith, 1979).

Marchantia polymorpha is generally regarded as a cosmopolitan weed of habitats disturbedby man. Along with Lunulariacruciata, anotherliverwort. it is common in gardens. Both plants have a flat, green, leafless, irregularly branched body and are easy to distinguish with the naked eye. They both produce gemmae. In Marchantia these are contained in a fringed cup near the apex of the plant. In Lunularia they are embraced by a crescent shaped ridge: hence the name Lunularia, a little moon. Marchantia is named after Nicholas Marchant, a director of the botanic garden of Gaston d'Orleans in Blois, France.

A habitat which we know has changed greatly in recent years is that of arable fields. Until the practice of ploughing immediately after harvest, it was in these fields that some species of bryophytes could most readily be found.

The two British species of the liverworth genus Sphaerocarpos - S. michellii and S. texanus - are practically confined to this habitat. The more common, Sphaerocarpos michellii, has a mainly East Anglian distribution (Smith, 1978b). A few years ago it was common in a few fields near Hadleigh and is probably still there. But knowledge of its occurrence in the rest of the county is incomplete. The spores of both species mature in November-December, long after ploughing (Macvicar, 1926). They are very small, circular, whitish green plants and should be looked for in unploughed fields and field margins during winter. If arable fields are taken out of production, bryologists will want to study them to see what plants have survived.

The genus Sphaerocarpos is famous in genetics, as it was in an American species that chromosomes were found which were interpreted as providing the first evidence of sex chromosomes in plants (Schofield, 1985).

In a county like Suffolk with little or no natural outcrops of rock, epilithic species are confined to walls and buildings, especially churches. Much attention nowadays is given to the conservation of churches and churchyards, but the bryophyte flora is seldom mentioned. Yet a churchyard may contain 20-30 species, some restricted almost entirely to those habitats, and may be more important for bryophytes than any other plant group. Some may be quite rare.

With the publication of a paper in 1985, the moss Leptobarbula berica was recognised for the first time as part of the British flora (Appleyard, Hill& Whitehouse, 1985). Previously it had beenconfused with other species to which it bears a remarkable resemblance. This small plant has a Mediterranean-Atlantic distribution. In 1988 it was seen on a Suffolk church. Although male and female plants have been found in Britain, fruit has only been observed once. This may be due to our climate, for it fruits in Mediterranean countries.

The problem of dispersal of plants which rarely fruit is a difficult one with which to deal. The field bryologist will find apparently sterile plants at least as often as those in fruit. Some species, as we have seen, produce special

Trans. Suffolk Nat. Soc. 25

70

Suffolk Natural History, Vol. 25

propagules which aid in vegetative reproduction; and any part of a bryophyte - a leaf, or a branch falling off can, in suitable circumstances, give rise to a new plant. So a lack of spores is not a complete barrier to dispersal.

As a final example, let us take the moss Rhytidium rugosum. This plant has a mainly north western distribution in the British Isles, but it also flourishes in the Breckland. Fruit is unknown in the British Isles. Writing about this species, Schofield (1985) points out that it is very widespread in the Northern Hemisphere; in North America from the arctic down mountain chains to Mexico; and is equally widespread in Europe and Asia. Yet throughout its entire ränge fruit is very rare; and the only apparent means of dispersal is from the regeneration of fragments broken off the plant. Rhytidium rugosum is one of a small number of mosses which produce very few rhizoids (Crundwell, 1979). It is easily detached from the soil and complete plants can sometimes be seen lying on the ground of Breckland heaths. Pieces break off and are blown about; but as Schofield concludes, 'regeneration from fragments would appear to be a very slow means of expanding populations. In spite of this, the species has achieved most of its present distribution since the glacial retreat some 10,000 years ago'.

Like many mosses, this species is dioecious: the male and female Organs are on separate plants. As the sperms have to swim through a film of water to reach the female Organs, fertilisation is impossible unless male and female plants grow close together, which often does not happen. Genetically the dioecious condition promotes Variation within a species; but it is difficult to understand what ultimate value it can have in species which fruit so rarely.

Sixty years ago, bryology was a world on its own. Today we can no longer afford such privacy; the threats to our flora are too many and too great. That is why I have tried to show that there is more to bryology - and bryologists than grim taxonomy in a forbidding corner of the natural world.

References Aiton, W. (1811). A Treatiseon Moss. The Highland Society. Air, Scotland.

Appleyard, J., Hill, M. O . & Whitehouse, H. L. K. (1985). Leptobarbula berica (De Not.) Schimp. in Britain. J. Bryol. 13, 461.

Banergee, R. D. & Sen, S. P. (1979). Antibiotic activity of bryophytes.

Bryologist 82, 141.

Berkeley, M. J. (1863). Handbook of British Mosses. Lovell, Reeve & Co. London.

Briggs, D . (1972). Heavy metal tolerance in bryophytes. J. Bryol. 7,149.

Corley, M. F. V. & Hill, M. O. (1981). Distribution of Bryophytes of the British Isles. A Census Catalogue of their occurrence in Vice-Counties.

British Bryological Society. Cardiff. Amended annually in the Bulletin of the British Bryological Society. Cardiff.

Crum, H . (1983). Mosses of the Great Lakes Forest. 3rd Edn. University of Michigan, USA. Crundwell, A. C. & Nyholm, E. (1964). The European species of the Bryum erythrocarpum complex. Trans. Br. Bryol. Soc. 4, 597.

Trans. Suffolk Nat. Soc. 25

SUFFOLK MOSSES A N D LIVERWORTS

71

Crundwell, A . C. & Whitehouse, H. L. K. (1978).

Trichostomopsis umbrosa (C. Muell.) Robins. in England. J. Bryol. 10, 5.

Crundwell, A . C. (1979). Rhizoids and Moss Taxonomy. In Bryophyte Systematics, eds. Clark G . C. S. & Duckett J. G . Systematics Association special volume No. 14,195. Academic Press, London.

Eckel, P. M. (1986). Didymodon australasiae var. umbrosus.

New to Eastern North America. Bryologist 89, 70.

Gerson, U . (1982). Bryophytes and Invertebrates. In Bryophyte Ecology ed.

Smith A . J. E. C h a p m a n & Hall, London.

Kreulen, D . J. W. (1972). Spore Output of moss capsules in relation to ontogeny of archesporial tissue. J. Bryol 7,61.

Macvicar, S. M. (1926). The Student's Handbook of British Hepatics. V. V. Sumfield, Eastbourne.

Mayfield, A . (1930). The Hepatics, Mosses & Lichens of Suffolk. Journal of the Ipswich and District Nat. Hist. Soc. 1, 89.

Mayfield, A . (1930). Notes on the plant life of Mendlesham with special reference to the Hepatics. Journal of the Ipswich and District Nat. Hist.

Soc. 1, 192.

Preston, C. D . & Whitehouse, H. L. K. (1985). Trichostomopsis umbrosa in semi-natural habitats. J. Bryol. 13,471.

Rao, D . N. (1982). Response of Bryophytes to Air Pollution. In Bryophyte Ecology ed. Smith, A . J. E. Chapman & Hall, London.

Richardson, D . H . S. (1981). The Biology of Mosses. Blackwell Scientific Publications, Oxford.

Schofield, W. B. (1985). Introduction to Bryology. Macmillan Publishing C o m p a n y , New York.

Smith, A . J. E. (1978a). The Moss Flora of Britain and Ireland. Cambridge University Press, Cambridge.

Smith, A . J. E. (1978b). Provisional Atlas of the Bryophytes of the British Isles. National Environment research Council, Huntingdon.

Smith, A . J. E. (1979). Towards an experimental approach to bryophyte taxonomy. In Bryophyte Systematics, eds. Clark, G . C. S. & Duckett, J. G . Systematics Association special volume No. 14, 195.

Suire, C. & A s a k a w a , Y. (1979). Chemotaxonomy of bryophytes: a survey.

In Bryophyte Systematics, eds. Clark, G . C. S. & Duckett, J. G . Systematics Association special volume No. 14, 447.

Townsend, C. C. (1982). Pictus scoticus, a new genus and species of pleurocarpous moss from Scotland. J. Bryol 12, 1.

Watson, E . V. (1985). The recording activities of the BBS (1923-83) and their impact on advancing knowledge. In British Bryological Society special volume No. 1, eds. Longton, R. E. & Perry, A. R., Cardiff.

A. C. Smith, End H o u s e , 24 Shelfanger R o a d , Diss, Norfolk, IP22 3 E H

Trans. Suffolk Nat. Soc. 25