Found on mossy, usually broad-leaved woodland or wayside trees, more rarely siliceous rocks. A very variable, widespread occurring in two equally frequent and widespread chemical races. The shrubby habit and widely divergent branching pattern is characteristic.

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