Family: Rhizocarpaceae
Rhizocarpon geographicum (L.) DC.
Map Lichen
Type: Crustose
Conspicuous bright yellow-green crustose lichen with flat black apothecia. Rather common on granitic rock
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