Thallus very variable in colour from pale grey to brown or almost black. Green when wet. Thalli are often circular, up to 3 cm in diameter but can be irregular. Long lobes about 1.5 mm wide divide near the tip looking like fingers. The lower surface is black with dark rhizines but these may protrude at the margins where they have white tips. White to greenish soralia, covered in a coarse powder, occur on the surface and occasionally at the margins.
Chemistry: Medulla K-, sometimes with yellow patches which are K+ purple.
Similar species: Hyperphyscia adglutinata has smaller (lobes to 0.5mm wide) and very closely adpressed to the substratum, only rarely on stone.
Nutrient-enriched bark and twigs and basic stones especially on urban concrete.
Throughout Britain and Ireland.
Text by David Brabban