Foliose, green to green-brown when wet and glossy brown when dry. The lobe margins are erect, crisped and often sorediate. Found on both coniferous and deciduous trees

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