A foliose species with lobes that are dark brown to grey-brown, but often appears grey as the upper surface is covered in a coarse network of white or pale grey pseudocyphellae. The lobes expand at the apices which are characteristically square cut.
Cortex: K+ yellow. Medulla: C-, K+ yellow-red, UV+- glaucous
In Scotland, Parmelia omphalodes is widespread in upland areas where it is found on well-lit, hard, nutrient-poor, siliceous rocks such as granite and sandstone. BLS distribution map
Parmelia omphalodes is separated from Parmelia saxatilis and Parmelia sulcata on basis of the brown colour and the lack of isidia and soralia.
scottishlichens.co.uk 