Thallus to 10(-15) cm diam., discrete, often ± orbicular, ± appressed. Lobes 0.5-2 mm broad, usually radiating, ± separate to overlapping, grey- to dark brown when dry, greenish grey when wet, usually white-pruinose at least towards the lobe ends, not ciliate, sometimes with secondary lobules in the centre of the thallus, without soredia or isidia. Undersurface whitish at lobe tips, becoming blackish towards the centre, with black bottle-brush-like rhizines often forming a dense, interwoven mat. Upper cortex formed of densely packed thick-walled hyphae. Photobiont trebouxioid. Anamorph: conidiomata pycnidia, 0.2-0.3 mm diam., frequent, immersed or in small warts, walls hyaline except for a brownish ostiolar region. Conidia 5-7 × 1-1.5 μm, bacilliform, aseptate, hyaline, smooth, without a gelatinous sheath or epispore. Teleomorph: ascomata apothecia, to 5 mm diam., numerous, laminal, the thalline exciple persistent, sometimes incurved, often with secondary lobules. Disc usually grey-white pruinose. Thalline exciple present, persistent, often incurved, sometimes with lobules or soredia. Epithecium brown. Hymenium and hypothecium hyaline. Interascal tissue of paraphyses, simple or branched above, the apices slightly clavate, light brown and immersed in a mid brown epithecial gel. Asci cylindric-clavate, 8-spored, Lecanora-type. Ascospores (25-) 27-38 × 13-20 μm, greenish when immature and dark brown when mature, finely warted, 1-septate, thick-walled, with a strong, thickened broad septum, not thickened at the apices, without a gelatinous sheath or epispore. Chemistry: cortex and medulla K–.