Derbyshire feather-moss (Thamnobryum angustifolium)

SizeStem length: up to 40 mm

The Derbyshire feather-moss is classified as Critically Endangered (CR) on the IUCN Red List (1). Classified as Critically Endangered in the UK. Protected under Schedule 8 of the Wildlife and Countryside Act (as amended).

Although clearly related to the widespread moss Thamnobryum alopecurum, the Derbyshire feather-moss (Thamnobryum angustifolium) has more distinctive narrower leaves with very coarsely-toothed tips. Like its relative, the species has a tree-like structure, but its stems are more slender and their branches are further apart.

This moss is probably endemic to Britain, with the only known specimens being found in Derbyshire. Its location is kept secret.

Derbyshire feather-moss is found on vertical limestone rock faces, which are damp, and shaded. It also grows under water.

Mosses are an ancient group of plants, and often the first to colonise a bare surface. They do not produce flowers or seeds, but usually reproduce vegetatively or by developing capsules, the fruiting bodies which contain spores. Neither do they have roots. They maintain their footholds with rhizoids, with which they anchor themselves to rock or the ground. Derbyshire feather-moss has never been observed to produce fruiting bodies. When growing underwater it forms dark green clumps, but as the water recedes in the summer months the moss desiccates, and the stems can turn a reddish-brown. Limestone encrustations, which form on the underside of the plant, are particularly apparent at this time of year.

The chief threat to the Derbyshire feather-moss is deterioration in the quality of the water within its only native area.

Derbyshire feather-moss is included in English Nature's Species Recovery Programme (SRP). Because of its rarity and the risk from unscrupulous collectors, its main locations are kept secret. Anyone wishing to see it must contact the site manager first. This may seem like an extreme measure, but with a species this rare, and comprising the only known populations in the world, it is dangerous to take risks.

In order to safeguard the future of this moss, not only is it vital to protect the sites where it occurs in the wild, but attempts are also being made to propagate the moss ex-situ. This will enable possible re-introductions back into the wild, and it also offers an insurance against extinction. To lose any species, even something as easily overlooked as a moss, would further impoverish our natural world.

This information is awaiting authentication by a species expert, and will be updated as soon as possible. If you are able to help please contact:

  1.  IUCN Red List (April, 2011)