Widespread on both trees and rocks. Similar to Parmelia saxatilis but differs in having laminal soralia and not isidia

Determiner: 
Christine Johnson

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