Weissia multicapsularis Mitten 1851

Some species of moss are described as 'ephemeral', meaning they exist at a site for a relatively short time - perhaps 3 to 4 years - before disappearing from that site and cropping up elsewhere. These mosses are able to spread their spores, the moss equivalent of seeds, over some distance. Weissia multicapsularis may be unable to do this although a more critical factor may be that the spores do not land on bare ground with precisely the right conditions to allow germination. Where it does colonise, however, the moss may persist at some of its sites for many years.

The status of this moss is giving conservationists cause for grave concern. Apart from France, this moss has only ever been recorded in Britain. As the French population was destroyed by construction work on the only known site in 1997, this species may well be at severe risk of global extinction. Weissia multicapsularis is listed in the UK Biodiversity Action Plans and is one of the threatened mosses on English Nature's Species Recovery Programme. Efforts to save the moss have concentrated on management of the three sites where there are still reasonable sized populations. The work involves maintaining a suitable habitat for the moss, including clearing scrub and large over-shading vegetation, and weeding by hand around some the bank-top colonies. Small pieces of the moss have been removed for identification purposes and a few are in culture as part of English Nature's project, together with the Royal Botanic Gardens, Kew, to maintain a 'bank' of threatened mosses and liverworts. These cultured specimens could be used for re-introduction programmes if the moss becomes extinct in the wild.It is hoped that this species can be saved from complete extinction in its wild habitats. Mosses, though easily overlooked, are still an important part of our natural heritage, and we should strive to keep them as part of the Earth's rich diversity of life.

This moss, with its curious English name, forms small patches on the ground and on Cornish hedge banks. It forms small patches on damp, open bare ground and produces short shoots, often under 1 cm tall, with leaves that narrow at their tips. In colour it is mid-green to yellowish, and care should be taken in identifying this moss as it bears a close resemblance to other Weissia species. The tiny spore-bearing capsule is hidden amongst the upper leaves.

This species grows on damp and muddy soils in non-calcareous areas. On its Cornish sites it has been found on banks and tracksides near the coast, and on inland hedge banks.

The moss is endemic to two parts of western Europe, and has been reported from some 25 locations. However, it has undergone a marked decline and, today, is known from only 3 sites. In the UK it is restricted to south-west England, and from most of, Cornwall although there is an old record from South Wales. It has also been recorded in France.

Classified as Critically Endangered in the UK Classified as Endangered in Europe.

The moss is at risk from several factors. The most threatening is the use of chemicals and fertilisers on arable farmland. The moss risks being 'crowded out' by competing grasses and other larger plants from over enrichment of the soil. Weissia multicapsularis also requires bare ground with the right conditions on which to establish, and if this is not available within the range of its spores, the moss cannot establish a new colony. Why it fails to germinate on some apparently suitable sites is something we know very little about.

Weissia multicapsularis, the many-fruited beardless-moss, is an ephemeral moss. It is critically endangered.

Weissia multicapsularis là một loài rêu trong họ Pottiaceae. Loài này được (Sm.) Mitt. mô tả khoa học đầu tiên năm 1851.