Ochrolechiaceae Lepra albescens var. albescens (Pertusaria albescens var. albescens) Growth type crustose Chemical reactions negative. Taste-test for oxalic acid negative Common on mature, slightly shaded trees, occasionally found on rocks or over-growing mosses. Very variable thick or thin, +/- waxy pale grey to dark green-grey thallus with an often zoned margin. The scattered or contiguous pale soralia can be disc-like or form large clumps. Similar: P. albescens var. corallina and Pertusaria amara (KC+ violet)

Pertusaria albescens var. albescens
On Oak. Holton Lee, Dorset. April 2013