Thallus orbicular to spreading, loosely attached, 6-15 cm diam., corticolous, rarely saxicolous. Lobes rounded, 5-12 mm wide, margins crenate to dissected-isidiate, ciliate, cilia numerous, black, 1-3 mm long. Upper surface smooth, pale grey to whitish, matt, slightly reticulate-cracked, isidiate, especially at or near margins, or sorediate-isidiate, isidia soon becoming granular and sorediate. Isidia at first small, simple, terete, delicate, brown-tipped, becoming granular-sorediate and ciliate, cilia black, to 3 mm tall. Soralia marginal, derived from isidia, capitate or glomerulate, eventually becoming recurved. Lower surface black, with a naked, tan or whitish, marginal zone. Rhizines central, black, simple. Apothecia not seen. Chemistry: Cortex K+ yellow; medulla K-, C-, KC+ red, Pd-. Alectoronic and α-collatolic acids (UV ± bluish-white) and atranorin.