Maritime Sunburst Lichen
Xanthoria parietina on a live branch of Common hazel (Corylus avellana).
Xanthoria parietina (Teloschistaceae) is a conspicuous yellow foliose lichen that contain a compound that acts as both a sunscreen for the algal partner and also protects them from harmful UV rays. Hence this species is often found in sunny exposed places.
This lichen is tolerant of high levels of nitrogen, especially ammonia, and is common on trees and buildings near farmland. So, Xanthoria parietina can be used as a monitor for nitrogen in the atmosphere.
The species is widespread over Britain, Europe and America but in tropical countries and in Australia it is rather rare.
Photo credit: ©Erminio Ferrari