Slender green feather moss  (Hamatocaulis vernicosus)

Classified as Nationally Scarce and is protected under Schedule 8 of the Wildlife and Countryside Act 1981 in Great Britain; it is listed on Annex IIb of the EC Habitats & Species Directive, and Appendix I of the Bern Convention (3).

Slender green feather moss is a straggling moss (4), which has green to brown erect shoots, with hooked tips, reminiscent of a walking stick (3). This trait is referred to by the scientific name Hamatocaulis, which derives from the Latin for 'hooked stalk' (5).

This moss has been confused in the past with similar species, but recent survey work has clarified its UK distribution (4). Although it has been recorded throughout Britain, it is frequent only in parts of north Wales and the north-west of England (4), and is rare in the rest of England and Scotland (3).

This species occurs in mineral rich mires (3), flushes and springs, and more rarely in lowland fens (4).

Little is known of the biology of this species. Mosses, hornworts and liverworts form a group of plants called bryophytes (3). 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).

This species has undergone a decline in the last century, but the severity of this decline is not clear because of widespread confusion with other mosses (3). Eutrophication and a decline in grazing are thought to have resulted in the loss of the species in East Anglia, changes in grazing, atmospheric pollution, forest creation and disturbance or drainage of mires are all thought to be responsible for the decline of this species in the rest of Britain (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, and to increase populations where possible (8).

Information authenticated by Royal Botanic Gardens, Kew:
http://www.rbgkew.org.uk/

• Capsule: in mosses and liverworts, the spore-bearing structure, held aloft on a stalk called a seta. Capsules have a variety of shapes. Most moss capsules have a mouth, which is covered by a lid until the spores become ripe and the lid falls off, revealing a single or double ring of teeth, known as the ‘peristome’. The spores are released and dispersed in the wind. In liverworts the capsules do not have lids; when the spores are ripe the capsule splits into four, releasing the spores.
• Eutrophication: nutrient enrichment of aquatic or terrestrial ecosystems.
• Gametophyte: a life cycle stage in plants, which has one set of chromosomes (threads of DNA protein) in the cell nucleus (a condition known as ‘haploid’), which arises from a spore (which is also haploid). Sex cells (gametes) are produced during the gametophyte stage. This is the dominant life-cycle stage in liverworts and mosses.
• 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.
• Spores: microscopic particles involved in both dispersal and reproduction. They comprise a single or group of unspecialised cells and do not contain an embryo, as do seeds.
• Sporophyte: the stage of a plant life cycle that produces spores (microscopic particles used in dispersal and reproduction). This stage is diploid (in the cell nucleus there are two sets of chromosomes - threads of DNA protein) and is dominant in ‘higher’ plants such as flowering plants.
• Vascular system: in plants, the system that allows water and nutrients to move around.

1. National Biodiversity Network Species Dictionary (August 2002) http://www.nhm.ac.uk/nbn/
2. Smith, A. J. E. (1996) The moss flora of Britain and Ireland. Cambridge University Press.
3. Church, J. M., Hodgetts, N. G., Preston, C. D. & Stewart, N. F. (2001) British Red Data Books: mosses and liverworts. Joint Nature Conservancy Committee, Peterborough.
4. JNCC 1393 Slender green feather-moss. SAC selection information. (August 2002): http://www.jncc.gov.uk/ProtectedSites/SACselection/species.asp?FeatureIntCode=S1393
5. Latin Dictionary and grammar aid (August 2002): http://www.nd.edu/~archives/latgramm.htm
6. Mosses and Liverworts in Wales (August 2002): http://home.clara.net/adhale/bryos/
7. Egerton, H. & Jones, F. (Eds.) (1998) Nature Encyclopedia. Dorling Kindersley, London.
8. UK BAP Species Action Plan (August 2002): http://www.ukbap.org.uk