Species: Candelariella medians
Photos: On church wall. Macroom, Cork, SW Ireland.
Placodioid yellow lichen with a yellow or greyish-yellow areolate centre and flattened pruinose lobes. Colour is greyer in shaded situations. Brownish-yellow apothecia with smooth or crenulate margins and simple spores. Can form large patches.
Chemical reactions: K- (Caloplaca species are K+ red)
Usually found on man-made substrates, cement, concrete, gravestones. Less frequent on hard calcareous rocks.
Candelariella medians. Macroom, Co.Cork. December 2008