Thallus foliose, ± erect or pendulous or spreading, to 5-12(-15) cm tall, firmly attached by a ± root-like holdfast, supporting a short (1-2 cm), thickened, terete or ± canaliculate stalk. Lobes palmate, oftenimbricate, complex, with a distinctly grooved midrib, rather fragile, often ± fenestrate, brittle when dry, margins dissected, sinuses circular, irregularly lobed or notched, appearing phyllidiate. Upper surface bright green to greenish-yellow or olive, smooth or slightly wrinkled, matt, grooved-canaliculate in mid-line of lobes, often dark brown to black at base of lobes and on basal stalk, internal cephalodia visible as raised, hemispherical lumps. Lower surface pale greenish-white, glabrous, shining at margins, yellowish to dark brown or blackening towards centre, midrib conspicuously raised, dark red-brown and often short-tomentose, tomentum rather variable, thick, a ± uniform dark brown or pale white felt, to a short, sparse, pale pubescence on central ribs. Cyphellae ± numerous, small, scattered, pock-like with a poorly defined margin, hardly raised, membrane of pit yellowish-brown. Apothecia sessile, scattered, often crowded towards margins, rarely at centre, 0.5-4 mm diam., disc red-brown, smooth, matt, concave at first, becoming plane to subconvex with age, margins thick, striate-crenulate, inflexed at first, pale brown or pinkish, occluded with age. Ascospores fusiform, colourless, 1-3-septate, 30-38(-45) × 9-11 µm.