Porpidiaceae Porpidia cinereoatra Growth type crustose Chemical results: Medulla K-, C-, P- Can be locally common on exposed siliceous rocks, particularly in upland and coastal areas Thallus cracked to areolate, creamy-white or greyish, the black prothallus +/- visible. Apothecia large, often remaining partly immersed, discs black, blue-grey pruinose when young. Epithecium brownish-green. Similar: Porpidia macrocarpa, medulla K+/- yellow, P+/- orange. Porpidia crustulata, K+/- yellow, P+/- orange

Porpidia cinereoatra
Lychett Matravers, Dorset. January 2014