A thick, cructose lichen, cracked-areolate, greenish to grey-yellow in colour. Apothecia initially immersed but eventually emerge, with discs that vary in colour and shape, but mostly greenish or blackish.
Found on nutrient-rich siliceous rocks and walls. It is also parasitic on Tephromela and Lecanora species. Common and widespread.
Photograph of Lecanora sulphurea, taken March 2012 on old canal coping stone, Staffordshire. © Pete Hillman 2012. Camera used Panasonic Lumix DMC-FZ38.