Sterling Mosses

In which area do the British Isles contribute most to the global fauna and flora? You could make a strong case for our wintering wildfowl and waders or our breeding seabirds, but take a look at this list - percentages of the world’s species which we have in Britain. Bryophytes: 7% Vascular Plants: 1% Fungi: 1% Mammals: 2% Birds (breeding): 2% Reptiles: 0.2% Amphibians: 0.3% Insects: 0.5% Arachnids: 0.6% (these figures are subject to caveats as discussed below 2) I vote for Bryophytes (and indeed would literally vote for a moss if one were to stand in a general election). Britain is a global hotspot for bryophyte diversity. With 65% of European species, but only 15% of vascular plant species, these figures are also impressive if looked at from a European perspective. There are some species which in Europe only grow in parts of the British Isles -  the next place they grow being the Himalayas or Tropics. They like it here as they really enjoy being cold, wet and miserable. They form a very important part of our ecosystems. The mossy covering of a forest floor can be like a mini-forest with its own tiny inhabitants. As is  the case with lichens, bryophytes are sensitive to air pollution and so they act as bio-indicators. One of the interesting findings of the new atlas of British and Irish bryophytes is that many species have spread in response to a decrease in sulphur dioxide pollution over recent decades. Bryophytes produce spores, rather than seeds. They have root-like anchoring structures, called rhizoids but unlike the flowering plants these do not actively extract minerals and water from the substrate. There are three main  groups -  mosses, liverworts and hornworts. Winter is a great time to get acquainted with the moss and liverworts as, unlike the flowering plants, they tend not to die back. I've been making a concerted effort to get know these plants over the past few weeks. At the start they all look the same. Not just similar - the same. Now after several weeks of 'mossing about' I'm starting to see the moss from the trees. Here is the patch list. For the beginner, having some idea of the commonest species is very useful 1. There are over a thousand British species, which is daunting, however lot of these are rare or local. It's also useful to know which features to look out for. For example the common  Pointed Spear-moss, is quite easy to identify once you know it has spear-like points to the shoots (see below), otherwise it's just, yet more of the stuff not gathered by rolling stones.  Incidentally The Rolling Stones gather plenty of moss. To a man the ageing rockers are keen students of bryology3.

The patch has some good bryophyte habitats such as the disused quarry... ...and former tennis court...however nearly every tree, rock or wall will have some bryophytes Capsules come in many different forms and are a very useful feature for indentification. Do they droop or stand erect? Do they have a beak? Are they borne on stalks? Leaf form is also important. Some leaves have hair-like projections. A hand lens is very useful for looking at this kind of feature. Some of the most familiar liverworts grow as a flattened leafless 'thallus'.  However many species are leafy - rather like a flattened moss.

Is it an acrocarp or pleurocarp? - when identifying a  moss the first step is to decide which of these two groups it belongs to.

Acrocarps - Usually unbranched and erect - often forming a cushion - The spores emerge from the tips of the plant - Slow growing

Pleurocarps - Branch freely in a chaotic fashion (a tangled mess in fact) - Branches spread  in a creeping fashion - The spores emerge from the mid stem - Fast growing

Some very common  acrocarps

Atrichum undulatum - Common Smoothcap - Large moss growing erectly on woodland floor - long beak on the capsule - leaves undulating

Mnium hornum - Swan’s-neck Thyme-moss -  very common at the base of trees. -  rather like the previous species but without the undulations or beaked capsules and with shorter leaves

Tortula muralis - Wall Screw-moss -  cushions very common on houses / walls - can look greyish when dry - also grows on rocks

Polytrichum commune -  Common Haircap -  unmistakable large hummocks on ground in damp shady places -  leaves curve away from the stem

Some very common pleurocarps

Brachythecium rutabulum - Rough-stalked Feather-moss - abundant on rocks, walls, trunks, logs & on the ground - unbeaked capsules which have rough stems - very variable - if in doubt it may well be this one

Calliergonella cuspidata - Pointed Spear-moss - easily recognisable with spear points to shoots - grassy & rocky habitats

Rhytidiadelphus squarrosus - Springy Turf-moss - very common  in grassland, forms extensive swards - large shoots (10–15cm) - distinctive red stems

Kindbergia praelonga - Common Feather-moss - One of the commonest mosses - on logs, trunks, banks, lawns - feather-like - leaves on stem and branch, markedly different shape

Two easily identifiable  liverworts

Conocephalum conicum - Great Scented Liverwort - large (up to 2cm wide) thalli - proment  pores on smooth shiny thalli - damp, shady rocks or soil by rivers, streams

Pellia endiviifolia - Endive Pellia -  distinctive branched thalli - damp places such as dripping rock outcrops.

<sup>Resources
Mosses and Liverworts of Britain and Ireland - an excellent field guide
The species accounts from the field guide are available online

British Bryological society</sup>

¹ The top ten British bryophyes in terms of distribution
Kindbergia praelonga
Calliergonella cuspidata
Brachythecium rutabulum
Rhytidiadelphus squarrosus
Mnium hornum
Ceratodon purpureus
Lophocolea bidentata
Hypnum cupressiforme
Hypnum cupressiforme var. cupressiforme
Bryum capillare

² There are several obvious problems with the figures. They are approximate and tentative.  A particular problem is the disparity between described species and species that (are estimated to) exist - and the way in which this disparity varies between groups (e.g. birds are well known, fungi aren't).

The figure for byophytes would be more like 5% if we were to look at estimated number of species rather than known species.

Our flora and fauna is better known than anywhere else, so even a very low percentage like that for amphibians will probably be an over-estimate.

Birds are bit of a special case in that many migrate. However to only include breeding birds is a bit unfair to avifauna. Our wintering populations are at least as important as our breeding populations.

There are 598 on British Bird list so that's 6% approx of the world's species, however birds that have only ever been seen a few times, after having been blown off course (of which there are a lot) can't really, to my mind, be described as 'British'.

The list is by no means comprehensive  - there are several other groups.

^{3 The Rolling Stones being keen students of bryology is clearly a big fat lie -  as everyone knows that Bill Wyman prefers metal detecting.}

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