Description: Primary thallus squamulose, the squamules prominent, to 1 x 1.5(-3) cm, rounded, entire, lobed or weakly incised, horizontally spreading, with farinose soredia along the up-turned margin, grey-green to olive-green above, white and farinose below, often pale orange near the attachment point. Podetia grey-green to olive-green, smoothly corticated with large, finely sorediate patches, to 1.5 cm tall, pointed or with irregular small cups gradually broadening toward the base. Apothecia rare, scarlet red, developing on the margins of cups. Asci 8-spored, clavate, thickened at apex, with a K/I+ blue tholus and a K/I+ strongly blue outer gelatinous sheath, Cladonia-type. Ascospores 1-celled, hyaline, ellipsoid. Pycnidia scarlet red, slightly stalked or semi-immersed at the top of podetia or along the margins of cups. Conidia cylindrical. Photobiont chlorococcoid. Spot tests: K+ yellow, C-, KC-, P+ yellow, UV-. Chemistry: thamnolic acid; rhodocladonic acid in apothecia and pycnidia.
Note: a cool-temperate to boreal-montane, circumpolar species found on strongly weathered lignum, mosses, on the bases of trunks, sometimes on soil rich in humus; common only in the Alps, becoming much rarer southwards.
Growth form: Fruticose
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)