Thallus rather thick, stark white to pale or dark grey, continuous, sometimes rimose-areolate. Prothallus often conspicuous, white. Isidia 0.1-0.3 mm diam., abundant, often covering the thallus, simple, cylindrical or becoming coralloid, erect or ± decumbent and unoriented.
Anamorph: not known.
Teleomorph: fertile warts rare, 1.5-2 mm diam., convex, sharply constricted at the base, often with an uneven to warted upper surface enclosing 2-4 (-11) apothecia. Apothecial disc 0.3-0.5 mm diam., ± expanded, flat or ± convex, pale or dark brown, often faintly white-pruinose. Asci 2-spored. Ascospores 80-140 (-230) × 40-80 μm, the wall 2-3 μm thick, not zoned or striate.
Chemistry: thallus C–, K+ yellow to yellow-orange, KC+ yellow, Pd+ yellow-red, UV– (thamnolic acid).
Assessed by Woods & Coppins (2012) as of Least Concern.
Throughout the west and north of the British Isles. BLS map here.
On dry, siliceous rocks, mainly in upland areas, very rarely on bark (Betula) and wood.