Churchyard lecanactis  (Lecanactis hemisphaerica)

Classified as Near Threatened in Great Britain and is protected under Schedule 8 of the Wildlife and Countryside Act 1981 (3).

Churchyard lecanactis is a rare lichen that grows in crust-like formations (3). The name of the genus Lecanactis means 'shining small bowl' and refers to the reproductive fruiting body, which contains a bag-like structure that contains the spores(4).

It is known from 44 locations in south-east England (5), including sites in Somerset, Sussex, Suffolk, Kent, Dorset and Norfolk (3). Outside of the UK it only occurs in Italy (3).

Inhabits external church walls that face to the north or east (3), and are sheltered from both rain and light (6). It tends to occur in coastal areas and typically grows on plaster or mortar (3).

Lichens are remarkable organisms; they are stable combinations of an alga and/ or a cyanobacteria with a fungus, living together in a symbiotic association (4). The fungus causes the alga to release sugars, which allow the fungus to grow, reproduce and generally survive. The fungus provides protection for the alga, and enables it to live in environments in which it could not survive without the fungal partner (4). A general rule is that the fungal component of a lichen is unable to live independently, but the alga may live without the fungus as a distinct species (7). Many lichens are known to be very sensitive to environmental pollution, and they have been used as 'indicators' of pollution (8). Churchyard lecanactis has an extremely slow rate of growth (6).

Possible threats include the deterioration of walls on which the species occurs and repair of the walls using unsuitable materials (3). This lichen is prevented from spreading as suitable external walls are in short supply (3).

The churchyard lecanactis is a UK Biodiversity Action Plan Priority Species, the Species Action Plan, which is lead by the wild plant charity Plantlife, aims to maintain the existing populations and to create three new colonies by 2005 (3). In addition, Plantlife has included the churchyard lecanactis on its Back From the Brink programme (8) and has produced a leaflet 'Churchyard Lecanactis: old walls can harbour secrets', available on request from Plantlife (enquiries@plantlife.org.uk) (5). In 1990 the British Lichen Society set up the Churchyards Project, this project is concerned with research, conservation and education on lichens of churchyards (9). Regular survey work is carried out, and leaflets containing conservation guidelines have been produced (9).

For more on churchyard lichens see the British Lichen Society's article available on-line at:
http://www.thebls.org.uk/chlich.htm
and the Plantlife leaflet 'Churchyard Lecanactis: old walls can harbour secrets' available from enquiries@plantlife.org.uk For more on British lichens see: Dobson, F. (2000). Lichens. An illustrated guide to the British species. The Richmond Publishing Co. Ltd., Slough.

Information authenticated by Plantlife, the wild plant conservation charity:
http://www.plantlife.org.uk

• Alga: a collection of taxonomically unrelated groups that share some common features but are grouped together for historical reasons and for convenience. They are of simple construction, and are mainly photoautotrophic, obtaining all their energy from light and carbon dioxide, and possess the photosynthetic pigment, chlorophyll A. They range in complexity from microscopic single cells to very complex plant-like forms, such as kelps. Algal groups include blue-green algae (cyanobacteria), red algae (rhodophyta), green algae (chlorophyta), brown algae and diatoms (chromista) as well as euglenophyta.
• Cyanobacteria: a group of bacteria that are able to photosynthesise and contain the pigment chlorophyll. They used to be known as ‘blue-green algae’. They are thought to have been the first organisms to produce oxygen; fossil cyanobacteria have been found in 3000 million year old rocks. As they are responsible for the oxygen in the atmosphere they have played an essential role in influencing the course of evolution on this planet.
• Fungus: fungi are one of the taxonomic kingdoms, separate from plants and animals. They obtain nutrients by absorbing organic compounds from the surrounding environment.
• 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.
• Symbiotic relationship: relationship in which two organisms form a close association, the term is now usually used only for associations that benefit both organisms (a mutualism).

1. National Biodiversity Network Species Dictionary ( November 2002) http://www.nhm.ac.uk/nbn/
2. Purvis, O.W., Coppins, B.J., Hawksworth, D.L., James, P.W., & Moore, D.M. (1992) The lichen flora of Great Britain and Ireland. The British Lichen Society, London.
3. UK BAP Species Action Plan (Nov 2002): http://www.ukbap.org.uk
4. Dobson, F. (2000) Lichens. An illustrated guide to the British species. The Richmond Publishing Co. Ltd., Slough.
5. Duckworth, J. (2002) Pers. comm.
6. NFU (Nov 2002): http://www.nfucountryside.org.uk/news/showarchivenews.asp?newsid=318
7. Church, J.M., Coppins, B.J., Gilbert, O.L., James, P.W. & Stewart, N.F. (1996). Red Data Book of Britain and Ireland: lichens. Volume 1: Britain. The Joint Nature Conservation Committee, Peterborough.
8. Plantlife (Nov 2002): http://www.plantlife.org.uk/uk/plantlife-saving-species-under-our-care.html
9. British Lichen Society: Lichen churchyard project (Nov 2002): http://www.thebls.org.uk/churyard.html