Description: Thallus foliose, heteromerous, forming rosettes or irregular, up to 15 cm wide, loosely attached. Lobes to 2 cm wide, elongate, partly overlapping, with entire to crisped, often lobulate margins. Upper surface yellowish brown to yellowish white, brown in sun-forms, greenish when wet, often pruinose and slightly pubescent, smooth to slightly scabrid, with wart-like cephalodia, esorediate; medulla white; lower surface corticated, pale brown to yellow-brown at margins, darker in central parts, glabrous or weakly pubescent, with rounded cephalodial warts and sparse, simple rhizines. Apothecia rare, immersed on lower surface at tips of lobes, orbicular, to 1.5 cm across, cup-shaped, with a brown disc and a prominent thalloid dorsal surface. Epithecium brownish; hymenium and hypothecium colourless. Asci 8-spored, fissitunicate, the thickened apex with a K/I+ blue ring, Peltigera-type. Ascospores 3-septate, pale brown, subfusiform, thick-walled, 17-21 x 5-6 µm. Pycnidia laminal, immersed, punctiform. Conidia rod-shaped, 3-4 x 1-2 µm. Photobiont: green algae (Coccomyxa); cephalodia with Nostoc. Spot tests: cortex and medulla K-, C-, KC-, P-. Chemistry: medulla with triterpenes and unidentified, UV+ substances.
Note: an arctic-alpine species found on soil and amongst bryophytes over siliceous substrata, near or above treeline; probably restricted to the Alps, where it exceptionally reaches the nival belt.
Growth form: Foliose, broad lobed
Substrata: soil, terricolous mosses, and plant debris