Porpidiaceae Porpidia crustulata Growth type crustose Chemical results: Medulla usually K+ yellow, C-, P+ orange Identification: Bryan Edwards Common on siliceous rocks, stones and pebbles, occasional on wood. Most frequent in lowland and urban areas. Very thin cream or pale-grey thallus sometimes only visible as dark stain (but can be reddish near water), the abundant black, convex apothecia (approx 1mm diam) usually in lines or groups. Porpidia soredizodes is the fertile counterpart Similar: Porpidea macrocarpa. Apothecia to 3mm diam

Porpidia crustulata
On pebble. Holton Lee, Dorset. March 2013