Beaked beardless moss (Weissia rostellata)

GenusWeissia (1)
SizeHeight: up to 5 mm (2)

Classified as Near Threatened in Great Britain, and receives general protection under the Wildlife and Countryside Act 1981 (3).

Beaked beardless moss is a small moss that grows in tufts on damp soil and drying mud (4).

This moss has always been considered as very scarce in Britain, and is believed to have declined (4), as it has disappeared from more than a third of recorded sites since 1950 (2). Recent records of this species come from Lothian to Anglesey and Dorset, and are thinly spread (3). In continental Europe, it has a scattered distribution from southern Norway and Sweden in the north, to France, Italy and Slovenia in the south, reaching as far east as the Ukraine (3).

This moss grows on damp soil or drying mud at the edges of reservoirs and pools, when the water recedes during summer and autumn. It also occurs in patches of bare soil by rivers (3), and in arable fields and damp grassland (4).

Mosses, hornworts and liverworts form a group of simple plants called bryophytes. Bryophytes lack many of the more complex structures of the higher plants, such as a vascular system, and flowers. They do not have roots, instead they have structures called 'rhizoids' which absorb water and anchor the plant to the substrate. All bryophytes have an interesting life cycle consisting of two main parts, called the gametophyte and sporophyte generations. Plants that are in the gametophyte stage can reproduce sexually. Male organs (antheridia) produce sex cells, which move to the female organs (archgonia). Fertilisation occurs and a 'sporophyte' develops, this structure remains attached to the plant. The sporophyte releases spores, which disperse and develop into a new plant (5).

A number of factors pose threats to this species, including the maintenance of permanently high water levels at occupied sites, drainage of damp pasture land (4), fertiliser use and other agricultural improvements that reduce the amount of bare patches (3). Other threats include eutrophication of water bodies, and the spread of the introduced invasive plant, New Zealand pygmy weed, Crassula helmsii (4), which blankets mud, removing suitable habitat, and scrub invasion (4).

Beaked beardless moss is a UK Biodiversity Action Plan priority species, and as such, it has a Species Action Plan to guide its conservation. It is also included in English Nature's Species Recovery Programme, which has part-funded survey work on this moss in conjunction with Plantlife, the wild plant conservation charity (4). Several populations occur within Sites of Special Scientific Interest (SSSIs), and so receive a degree of protection (3).

Information authenticated by Plantlife, the wild plant conservation charity:

  1. Systema Naturae 2000 / Classification- Parker (1982) - (July 2002):
  2. The Environment Agency (2000) Focus on Biodiversity. The Environment Agency, Bristol.
  3. UK BAP Species Action Plan (July 2002):
  4. Holyoak, D. T. (2002) Violet crystalwort (Riccia huebeneriana) and beaked beardless-moss (Weissia rostellata): Report to Plantlife on work carried out in southern England during 2001. Report number 198, ISBN 1 87261369 1. Plantlife, London.
  5. Mosses and Liverworts in Wales. (July 2002):