Thallus foliose, to 5 cm (rarely to 10 cm) diam., rosette-forming or irregular, loosely appressed, the margins usually ascending, often becoming roughened and irregularly pitted. Lobes to 3 mm wide, flat, often partially overlapping, lacking pseudocyphellae. Upper surface varied in colour, ranging from pale greenish-olive to olive-brown or dark brown [presumably depending on exposure and hydration], often with a reddish or yellowish tinge, ± matt, usually pruinose at least in part. Lower surface ± black, with simple rhizines. Lobe edges with sometimes copious hyaline cortical bristle-like hairs (×20 lens). Soralia laminal and/or marginal, initially olive-green but becoming farinose and silvery when eroded, usually confluent towards the centre of the thallus; soredia coarsely granular or sometimes appearing isidial. Photobiont trebouxioid. Anamorph: not known. Teleomorph: not known in GB&I material. Ascomata apothecia, rare, 1-2 mm diam., sessile, the exciple sorediate. Ascospores 11-13 x 7-8.5 µm, broadly ellipsoidal. Chemistry: cortex C–, K–, N–, Pd–; medulla and soralia C+ red, K–, KC+ red, Pd–, UV– (lecanoric acid).