Sterile beardless moss  (Weissia sterilis)

Classified as Near Threatened in Great Britain (3).

Sterile beardless moss occurs as patches or scattered stems (4). The stems are usually branched, and the branches are often clustered together. The narrow leaves, which measure between 3.0 and 3.7 mm long become larger up the stem; they become 'crisped' when dry, but spread out when they are moist (2).

Most records from Britain occur in the south of England, from Worcestershire and Cambridgeshire south to Kent and south Devon (3). There is also an isolated population in Powys, Wales (3). This species has, however been lost from a number of sites in England (3). Elsewhere, sterile beardless moss only occurs in the north-east of France (3).

You can view distribution information for this species at the National Biodiversity Network Gateway.

This moss grows on dry calcareous soils, typically on bare patches amongst grass on south-facing slopes (3).

Little is known of the biology of this species. Mosses, hornworts and liverworts form a group of plants called bryophytes (5). 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 (6). Plants that are in the gametophyte stage can reproduce sexually. Male organs (antheridia) produce male sex cells or gametes called antherozoids, which actually move to the female sex organs (archegonia) (6) through water droplets (7). Fertilisation occurs and a plant develops called a 'sporophyte', which remains attached to the plant. The sporophyte releases spores from within a capsule; the spores disperse and develop into a new gametophyte stage plant (6).

The threats facing this species are not fully understood, however it is believed that the loss of grasslands as a result of conversion to agriculture and development, and scrub encroachment may have been responsible for the loss of this species at many sites (3).

A Species Action Plan has been produced for this moss under the UK Biodiversity Action Plan (UK BAP). This plan aims to maintain the current range of the species. Several populations occur within Sites of Special Scientific Interest (SSSI), and National Nature Reserves (NNRs), and therefore receive a level of protection (3).

There may be further information about this species available via the National Biodiversity Network Gateway.

The UK Biodiversity Action Plan for this species is available at UK BAP.