Parmelia (fungus)

Parmelia is a genus of medium to large foliose lichens. The ends of the leaf-like lobes are often squarish-tipped. The upper surface is pale bluish-gray to light brown in direct sunlight, with a network web-like ridges and depressions. The lower surface is black and has rhizenes anchoring it to the substrate.

It has a global distribution, extending from the Arctic to the Antarctic continent but concentrated in temperate regions. 125 species have been recorded on the Indian sub-continent. Depending on whether the circumscription of the genus is considered in the narrow sense (sensu strico) or the broad sense (sensu lato), there are between 50 to 1322 species world wide. It is a foliaceous lichen, resembling a leaf in shape. In recent years, the genus Parmelia has been divided into a number of smaller genera according to thallus morphology.

Description and ecology

In general, Parmelia have a dark lower side with rhizines ('rootlets') which attach the lichen to its substrate. The upper side may be several colours - grey, yellow, brown - and may have reproductive organs on it. These may be apothecia (spore producing bodies), isidia or soralia (both vegetative structures). In between these two layers is the medulla which contains the algal component of the lichen.