Sausage beard-moss  (Didymodon tomaculosus)

Classified as Near-threatened in the UK.

This moss was only recognised as a distinct species for the first time in 1981. It is very similar to other species of the genus Didymodon, being only a few millimetres tall, but it has distinctive sausage-shaped tubers on its rhizoids (the underground root-like filaments).

This species is found in the UK, Ireland, and recently in Germany. In the UK, it has been recorded in Derbyshire, North and West Yorkshire and in 2002 it was found in Shropshire. In Ireland it is recorded in counties Offaly and Kildare and, also in 2002, it was discovered in Co. Dublin.

Most of the records for this moss have been from arable fields on neutral clay soil, with some from trampled pastureland.

Very little is known about this species, but it seems to be characteristic of water-retentative soils. It appears to propagate itself by the underground tubers, which are disturbed and spread during arable cultivation.

With so little known about the ecology of the sausage beard-moss, it is difficult to assess why it seems so rare and what factors may be responsible for contributing to its rarity. It has probably been widely overlooked as a species, although a decline in the practice of leaving winter stubbles may be an important factor.

Sausage beard-moss is listed in the UK Biodiversity Action Plan, and included in English Nature's Species Recovery Programme. As so little is known about this moss, the plant conservation charity Plantlife are co-ordinating a systematic search for this species to gain a full understanding of its status and requirements. Eventually, if this species proves to be as rare as is currently thought, it may be possible to re-introduce it to suitable sites within areas covered by agri-environment schemes, such as the Arable Stewardship Scheme.

The UK BAP Species Action Plan is available on-line at:
http://www.ukbap.org.uk
For more on Plantlife see:
http://www.plantlife.org.uk

• Agri-environment schemes: these schemes allow the government to compensate farmers for using methods that benefit the environment. The two main initiatives in the UK are the Countryside Stewardship Scheme and Environmentally Sensitive Areas. Since October 2000 these have formed part of the England Rural Development Programme (EDRP), administered by DEFRA, the Department of Environment Food and Rural Affairs. See: http://www.defra.gov.uk/erdp/erdphome.htm for more on these initiatives.
• Rhizoids: thread-like structures that help to anchor the plant to the substrate, and absorb minerals and water. In liverworts they consist of a single cell, in mosses they are multi-cellular.