Lichens are remarkable organisms; they are stable combinations of an alga and/ or a cyanobacterium with a fungus, living together in a symbiotic association(7). 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 (7). 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 (4). Many lichens are known to be very sensitive to environmental pollution, and they have been used as 'indicators' of pollution (5). Much confusion has occurred between the New Forest parmelia and the related lichen, Parmelia horrescens (3).