Description: Thallus fruticose, once or twice dichotomously branched, cream-coloured, yellowish brown at the necrotic base, loosely attached, sometimes forming compact mats. Lobes 6-10 mm broad and 2-4 (-8) cm tall, (usually smaller in Italian material), foveolate and reticulately ridged, erect to ascending; underside corticate, with narrow, mostly marginal, whitish pseudocyphellae. Cortex thin, paraplectenchymatous in upper part; medulla white, rather lax. Apothecia extremely rare, zeorine, submarginal at lobe-ends, up to 8 mm across, with a brown disc. Epithecium brownish; hymenium and hypothecium colourless. Asci 8-spored, narrowly clavate, Lecanora-type. Ascospores 1-celled, hyaline, ellipsoid, 5-10 x 3-6 µm. Pycnidia black, marginal, slightly projecting. Conidia dumbbell-shaped (thickened at both ends), c. 6 x 1 µm. Photobiont chlorococcoid. Spot tests: cortex K-, C-, KC+ yellowish, P-; medulla K-, C-, KC-, P-. Chemistry: cortex with usnic acid; brownish parts at the base with anthraquinones.
Note: a circumpolar, arctic-alpine lichen, a typical element of tundra-like vegetation in open, dry habitats above treeline; common throughout the Alps, but surprisingly abundant also in the Gran Sasso Massif (Central Apennines).
Growth form: Fruticose
Substrata: soil, terricolous mosses, and plant debris
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by thallus fragmentation