Thallus orbicular to spreading, closely to loosely attached, 5-20 cm diam., corticolous and saxicolous. Lobes large (5-15 mm wide) subirregular, apically rounded with shallowly incised margins. Upper surface plane to undulate, yellowish or green-yellow (usnic aid in upper cortex), smooth, matt, at margins becoming coarsely wrinkled centrally, coarsely pustulate. Pustules large, yellowish-white, globose, laminal, diffuse or coalescing, rarely at margins. Medulla white, often with an orange pigment below pustules. Lower surface wrinkled, black with a narrow, wrinkled, naked brown, marginal zone. Rhizines sparse, simple, black or brown. Apothecia rare, 2-5 mm diam., margins coarsely pustular-sorediate, disc matt or shining dark red-brown. Ascospores 17-24 × 8-13 µm. Chemistry: Cortex K+ yellow; medulla K-, C-, KC+ rose, Pd+ red. Caperatic, protocetraric and usnic acids and atranorin. Skyrin present when pigmented.