Ciliate strap-lichen (Heterodermia leucomela)

Synonyms: Heterodermia leucomelos
KingdomFungi
PhylumAscomycota
ClassLecanoromycetes
OrderLecanorales
FamilyPhysciaceae
GenusHeterodermia (1)
SizeThallus diameter: 5-15 cm (2)

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

Ciliate strap-lichen has ribbon-like lobes (4) that are ivory white in colour (2), with long black projections at the edges (5). The lobes are upturned at the tips (5), and scramble over and amongst the surrounding vegetation (3). The lower surface of this lichen differs from the upper surface in that it is grooved, and has a powdery or cobweb-like centre (5). Indeed, the scientific name of this genus 'Heterodermia' means 'different skin' and refers to the contrast between the upper and lower surfaces of the lichen (5).

In Great Britain, the species occurs only in Cornwall, the Isles of Scilly (4), the Lleyn peninsula (6) and Anglesey, which is the northernmost extreme of its European range (4). Historically it was more widespread in southern England, and occurred in Devon, Wiltshire, Dorset, and West Sussex. This lichen has a wide distribution globally, occurring in most tropical and temperate areas. In Europe it tends to be a western species, preferring oceanic conditions (4). Good populations occur in south-west Ireland, and it is also known from the Channel Islands (3).

Inhabits exposed, sunny coastal cliff-tops, on moss-covered rocks or mossy turf (4).

Lichens consist of two different organisms, a 'mycobiont' (a fungus) and a 'phycobiont' (either an alga, which is a simple plant, or a cyanobacterium, a bacteria that can photosynthesise), which live together in a symbiotic association (7). Many lichens are known to be very sensitive to environmental pollution, and they have been used as 'indicators' of pollution (7). Ciliate strap-lichen reproduces asexually by producing microscopic structures called 'soredia'; masses of soredia look like a fine powder to the human eye, but actually consist of fungal threads (hyphae) and cells of the phycobiont (7). These structures are dispersed by the wind, by animals, or by simply falling to the ground (2), and enable a new lichen to become established.

The causes of the decline of the ciliate strap-lichen in Great Britain are thought to be over-collecting, air pollution, fires, and trampling (4). Competition with scrub and coarse vegetation is also a threat (3).

This lichen is a priority species under the UK Biodiversity Action Plan. The Species Action Plan aims to maintain and, where possible, enhance the known populations (3). All current populations receive a degree of protection, as they occur in Sites of Special Scientific Interest (SSSIs) (6), and the species is afforded special protection by Schedule 8 of the Wildlife and Countryside Act 1981 (3). The lead partner responsible for this species is the wild plant conservation charity Plantlife, which has included ciliate strap-lichen on its 'Back from the Brink' programme (8).

For more information on this species see:

Plantlife Species Dossier:
http://www.plantlife.org.uk/uk/assets/saving-species/saving-species-dossier/Heterodermia_leucomelos_dossier.pdf

For more information 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

  1. National Biodiversity Network Species Dictionary (May, 2002)
    http://www.nhm.ac.uk/nbn/
  2. Management recommendations for Heterodermia leucomelos. (May, 2002)
    http://www.or.blm.gov/surveyandmanage/MR/Lichens/HELE20.pdf
  3. UK BAP Species Action Plan (May, 2002)
    http://www.ukbap.org.uk
  4. Church, J.M., Coppins, B.J., Gilbert, O.L., James, P.W. and Stewart, N.F. (1996) Red Data Book of Britain and Ireland: lichens. Volume 1: Britain. The Joint Nature Conservation Committee, Peterborough.
  5. Dobson, F. (2000) Lichens. An illustrated guide to the British species. The Richmond Publishing Co. Ltd., Slough.
  6. Duckworth, J. (2002) Pers. comm.
  7. Allaby, M. (1998) Oxford Dictionary of Plant Sciences. Oxford University Press, Oxford.
  8. Plantlife (May, 2002)
    http://www.plantlife.org.uk