Thallus (1-) 2-6 (-10) cm long, 2-4 (-6) mm wide, about 1 mm thick, foliose. Lobes rather soft, numerous, strap-shaped, ± palmately branched, often twisted and pendulous. Upper surface green-grey to pale green-yellow, often with an incomplete network of elongate ridges spreading towards the margins enclosing hollows. Lower surface white, almost lacking photobiont, but occasionally dotted green especially toward the tips. Soralia marginal and/or laminal, at first rounded and often confined to eroded surfaces of ridges and/or lobe margins, later becoming confluent, paler or concolorous with the upper surface. Anamorph: conidiomata pycnidia, ca 0.3 mm diam. Conidia 6-7 × ca 0.5 μm. Teleomorph: ascomata apothecia, rare in Britain, 2-5 mm diam. Ascospores 7-11 x 4-6 μm. Chemistry: medulla C–, K–, KC–, Pd–, UV– (usnic and evernic acids, atranorin).