Found on acid-barked deciduous trees and on rock. Comprises transversely wrinkled lobes with coarse granular soredia. Yellowish green above with black under surface with light-brown margins and simple rhizines.

References: 
Smith, C.W. et al. editors (2009) The Lichens of Great Britain and Irelandd
Dobson, F.S. (2018) Lichens: an Illustrated Guide to the British and Irish Species
Thell & Moberg, editors (2011) Nordic Lichen Flora. Volume 4: Parmeliaceae