Candelariaceae Candelariella medians Growth type crustose, placodioid Chemical reactions: K- (Caloplaca species are K+ red) Usually occurs on man-made substrates; cement, concrete and gravestones. Less frequent on hard calcareous rocks. Yellow or greyish-yellow thallus with flattened, pruinose lobes, the centre areolate, +/- granular isidiate. Brownish-yellow apothecia rare, with smooth or crenulate margins and simple spores. Can form large patches, the colour greyer in shaded situations. Similar: Caloplaca decipiens is K+ red

Candelariella medians
Wareham and Sturminster Marshall, Dorset. August 2012, March 2014