Thallus foliose, lobate, dorsiventral, orbicular to irregular, usually loosely attached by a dense felt of rhizines, occasionally closely attached, to 12 cm diam. Lobes to 1 cm wide, dark greyish-blue, bluish-green or occasionally greyish-black when wet, leaden grey to pale whitish-grey when dry, adjacent, often imbricate, broadly cuneate to flabellate, apices rounded, often slightly thickened, margins ± entire, or variously minutely notched or incised or secondarily lobulate, ± conspicuously deflexed. Upper surface smooth, ± coriaceous to minutely wrinkled or in parts occasionally minutely scabrid, matt, in larger lobes few faint striae visible, arranged in parallel lines along the length of the lobes (×10 lens), often conspicuously ridged, ridges in transverse, concentric lines reflecting the attachment of rhizines to lower surface, isidiate or not, without maculae, pruina, pseudocyphellae, soralia or tomentum. Photobiont blue-green, . Lower surface corticate, usually pale, whitish or creamish, rarely blackened, ± densely rhizinate. Rhizines simple, pale or bluish-black, complex, entangled, or in ± discrete, transverse, concentric lines, rarely projecting beyond lobe margins. Apothecia ± frequent, (rare in ) discrete, rarely crowded, to 2 mm diam., laminal, sessile, scattered, rounded, biatorine or zeorine, disc concave at first, becoming plane or occasionally convex with age, matt, not pruinose, not gyrose-contorted, ± reddish-brown, occasionally blackened, proper margin entire, pale, sometimes blackened, sometimes with small white hairs at base, often excluded by disc or thalline margin, thalline margin present or absent. Ascospores simple, colourless, 8 per ascus, ellipsoid, uni- or biseriate, young spores usually with two oil droplets, mature spores with a somewhat roughened granular surface. Pycnidia ± frequent, wart-like, immersed, with a central black ostiole. Conidia rod-shaped.