Description: Thallus foliose to subfruticose, rather loosely attached, forming regular or more often irregular, up to 7 cm wide tufts. Lobes strap-shaped, at first adpressed, then ascending and free, irregularly branched, 1-4(-6) mm wide at base, narrowing towards tips, weakly channelled to flat, with scattered, grey to brownish marginal soralia, especially towards lobe tips. Upper surface pale brown to olive-brown, somewhat glossy, rather smooth; lower surface paler brown to whitish, wrinkled or sulcate, with a few punctiform, c. 0.1 mm wide, often poorly visible pseudocyphellae and rather scarce, pale rhizines toward the base. Upper and lower cortex paraplectenchymatous, the upper cortex covered with a thin, pigmented epicortex consisting of 1-2 layers of densely packed isodiametric cells; medulla white, rather loose. Apothecia extremely rare (not observed in Italian material), lateral and marginal, lecanorine, up to 3 mm across, with a brown disc and a sorediate thalline margin. Asci 8-spored, cylindrical-clavate, Lecanora-type. Ascospores 1-celled, hyaline, globose, c. 5 μm in diam. Pycnidia black, immersed in marginal projections. Conidia dumbbell-shaped (thickened at both ends), 5-6 x c. 1.5 μm. Photobiont chlorococcoid. Spot tests: cortex and medulla K-, C-, KC-, P-, UV-. Chemistry: protolichesterinic acid.
Note: on isolated conifers (e.g. Larix in the subalpine belt), more rarely on old acid-barked deciduous trees in montane forests; most frequent in the Alps, rarer in the mountains of southern Italy.
Growth form: Foliose, broad lobed
Photobiont: green algae other than Trentepohlia
Reproductive strategy: mainly asexual, by soredia, or soredia-like structures (e.g. blastidia)