Mosses

Mosses, liverworts and hornworts are collectvely called Bryophytes.  They are small flowerless green plants that reproduce through spores or asexually via gemmae or tubers.  Unlike flowering plants, ferns and conifers, they have no vascular system (the phloem or xylem vessels of flowering plants, ferns, conifers etc.)  Instead, water and nutrients diffuse directly into their thin tissue.  As early colonisers they can be found in virtually all terrestrial habitats. As well as being all around us, they are a good option to study in January and February when most other plants and invertebrates are absent.

Liverworts are in a separate NatureSpot gallery - they are either 'thallose' or 'foliose' (leafy), the latter with flattened shoots and leaves arranged in 2 or three ranks. Be aware that some mosses e.g. Fissidens and Plagiothecium have flattened shoots and can look similar to leafy liverworts.  Hornworts are rarely recorded in Leicestershire and Rutland, and currently NatureSpot does not have any records with images that can be displayed.

Facebook Group: Bryophytes of Britain and Ireland

The British Bryological Society provides some excellent online guidance to help identify mosses and liverworts.

The BBS guides to common mosses and liverworts are very useful.

Atherton, I., Bosanquet, S. & Lawley, M. (eds.) 2010. Mosses and Liverworts of Britain and Ireland: A Field Guide  BBS  is an accessible guide for non-specialists and is highly recommended. The BBS are currently planning a second edition.

Watson, E.V. (1981) British Mosses and Liverworts (3rd edition)  CUP has keys that are more technical, often based on cell shape and leaf characteristics that may require microscopic examination. Be aware that since it was published, there have been some changes in taxonomy, and some new species have arrived in the British Isles.  

Smith, A.J.E (2004) The Moss Flora of Britain and Ireland (2nd edition) CUP is the classic guide to mosses, illustrating all species known to occur in the British Isles and including a comprehensive key - essential for the serious bryologist.

To identify some mosses, you may need to look at the microscopic details of the leaves - e.g. the cell shape in different parts of the leaf; whether there is a nerve in the leaf; whether the leaf margin is toothed, etc.  For most species, the leaves are just one cell thick, and the shape of cells can be seen at low magnification.  The BBS website includes micro-photographs of the leaves of some species, and the drawings in Watson and Smith (refs. above) are very helpful.  To begin with you will need to decided if the moss is a Sphagnum, or is acrocarpous or pleurocarpous.

Pleurocarpous mosses have a mat-like growth, with many branched stems tangled together.

Acrocarpous mosses have tufted growth made up of separate upright shoots, often forming dense cushions.

Moss specimens will keep for a long time in paper packets (not plastic) once they have dried out. They re-hydrate very quickly once water is added.

If you know of other websites or books that you would recommend, do let us know: info@naturespot.org

Acrocarpous mosses

Acrocarpous mosses have a tufted habit of growth made up of separate upright shoots, which are usually simple but may be forked or with a few branches, often forming form dense cushions.  A few species are flattened with leaves in two ranks, e.g. Fissidens. In most cases the seta bearing the capsule arises from the tip of the shoot. 

The shape of the leaf is an important identification feature - often long and sharply pointed ('awl-shaped'), but also may be rounded or ovate with a blunt tip.  A few species have a 'hyaline' hair-point - a clear and transparent section at the leaf-tip - and other species have sickle-shaped leaves strongly curved to one side.  Identification can be very difficult, and details of leaf structure may be needed - e.g. cell shape, the presence of or a border or teeth on the leaf margin, the width of a nerve in the leaf. etc. - requring low or high power magnification. 

Some species bear 'gemmae' or 'bulbils' on leaf-tips, leaf axils, rhizoids, shoot or stem tips, etc.; these are the units of asexual reproduction and are usually small and rounded like buds or tubers.  Sexual reproduction produces the spore-bearing capsules, with protective hood-like 'calyptra' that are shed when the capsule is ripe.  The shape and number of 'peristome teeth' at the mouth of the capsule can be a useful identification feature. The male parts are called 'antheridia' and may form flower-like structures at the stem tips, surrounded by rosettes of leaves.  Female parts are 'archegonia', flask-shaped structures containing the egg, at the stem tip.  Mosses can be 'dioecious' (male and female on the different plants) or 'monoecious' (male and female on the same plant, in separate ('autoecious') or shared structures). 

Habitats vary from bare soil in woods, on dry exposed ground, in marshes, on trees branches and on rocks, stone walls, brick walls, concrete and  tarmac. 

Polytrichales - Polytrichaceae

The Hair-caps and related species (Polytrichum, Atrichum, etc.) are unusual bryophytes in that the leaves have plates of green tissue overlying the nerve down the middle of the leaf, at right angles to it.  This thickening of the central part of the leaf gives them a robust opaque appearance in contrast to the thin, single celled leaves of other mosses.