Thallus closely attached, forming regular or irregular, complete or partial rosettes or irregularly encircling twigs, to 20 cm diam., sometimes coalescing to form extensive colonies, corticolous, lignicolous, more rarely saxicolous, muscicolous or terricolous. Lobes numerous, ± radiating at outer edges, medium, very variable, 0.5-3.5 mm wide, distinct at margins, becoming intricately interwoven centrally and there associated with numerous, secondary lobes, terminal lobes irregularly or subdichotomously branched, occasionally ± palmate, contiguous throughout entire length or remaining discrete, often overlapping and becoming ± compressed and distorted centrally, margins sinuous-contorted, entire, occasionally notched, sometimes with very short laterals, not, or sparingly, or rarely notably blackened (in exposed habitats), apices concolorous with thallus or ± suffused-brownish, hollow, lower side of internal cavity with a grey-white, thin, arachnoid tomentum. Upper surface uneven, whitish-grey, pale grey or green-grey, emaculate, ± rugose-uneven, shining, without isidia or soredia. Perforations frequent, median, large, gaping, 0.5-1(-2.0) mm diam., rounded or somewhat irregular through mutual compression of lobes, not elevated, margins depressed or inrolled around perforation. Apothecia numerous, on short inner, often lateral lobes towards centre, usually scattered or becoming clustered, verrucose at first, then markedly turbinate with an elongate or short, stout pedicel, 4-6(-7) mm diam., cupulate, margins thick, becoming thinner at maturity, areolate-striate, exciple coarsely scabrid, disc concave, pale brown, dark brown or red-brown, smooth, shining, epruinose. Epithecium red-brown without granules. Asci 8-spored, cylindrical or ± long-ellipsoid, 100-120 × 40-45 µm. Ascospores ellipsoid, 25-30(-39) × 20-22(-24) µm, wall 2-2.5 µm thick. Pycnidia numerous, clustered on short lateral lobes at centre, rare on marginal lobes, dark red, apices brown. Chemistry: Atranorin (cortex) one or two fatty acids and a UV-, yellow pigment in the medulla (±); medulla K-, C-, Pd-.