Thallus foliose, lobate, spreading, loosely attached, to 16 cm diam., corticolous, occasionally saxicolous or terricolous. Lobes rounded, overlapping or sometimes broadly laciniate, margins entire or slightly crenulate, often sorediate, subascendent, ± thickened in sorediate parts. Upper surface undulate, scrobiculate-reticulate but without strongly defined interconnecting ridges, matt or shining, dark bluish-green or greyish-blue when wet, pale yellowish-green or olive-buff when dry, suffused brownish at margins and there markedly scabrid-areolate, without isidia, phyllidia, maculae or pseudocyphellae. Soredia laminal and marginal, in spreading, erose soralia, punctiform on lamina at first, then eroding, ± linear at margins, whitish or greyish, becoming bluish with age, coarse, granular. Medulla white. Lower surface white, delicately scabrid at margins, uneven or ± wrinkled-bullate, not distinctly veined but with naked, whitish, scabrid patches scattered among pale tan to dark brown tomentum which extends to the margins, tomentum silky, entangled. Apothecia and pycnidia not seen. Chemistry: Cortex K-; medulla K+ orange-red, C+ rose or -, Pd+ orange. Constictic, norstictic, stictic and usnic acids and scrobiculin.