Thallus grey, with spreading lobes up to 7 cm in diameter. The lobes are smooth, rounded and up to 1 cm wide. The surface is has small white spots where the upper surface is broken. Soredia form a coarse powdery covering over these spots. The lower surface is light brown to white. Very rarely fertile.
Chemistry: Medulla and soredia: C+ carmine-red, KC+ red, UV-
Similar species: P. borreri and P. reddenda are similar but have a black lower surface. P. jeckeri has the powdery soredia mainly on the margins of the lobes and white crystals at the lobe tips.
See also Fungi of Great Britain and Ireland
On well-lit trees and moss, also on acid rocks and memorials. Tolerant of moderate nitrogen enrichment.
Throughout Britain and Ireland but becoming rarer in the north.
Text by David Brabban & Neil A Sanderson