Lichens are a compound organism composed of a fungus with an alga and sometimes a cyanobacterium. They co-exist in a mutually benefical partnership: the algae and/or cyanobacteria are protected from the environment by the fungal body, and the fungus receives nutrients from the algae which are produced by photosynthesis. The cyanobacteria also have the ability to fix nitrogen. This complex relationship enables lichens to colonise a very wide range of habitats.
The lichens of the islands are reasonably well documented with a total of over 500 species, compared with 2,200 for Scotland as a whole, recorded in the British Lichen Society's Scottish database (please refer to National Bodiversity Network Gateway for further information).
We began to have a serious look at fungi and lichens in the autumn of 2010 and so far have concentrated on the fungi. It is now our intention to look more closely at the lichens and have therefore created a separate section in the website to cover these species. Traditionally lichens have been organised by type i.e. thallus structure, for identification purposes, therefore a photographic index based on type rather than taxonomic family has been provided. The accounts of individual species can be accessed through the A-Z index, or by using the search facility.