Thallus foliose, in large patches to 60 mm diam. or more; of elongate, radiating, overlapping lobes, several cm long and 0.4-1.5 mm wide. Lobes convex, somewhat flattened, copiously banched, white to pale brownish grey or glaucous, sometimes darkened to blue-black at the often inflated tips, turning bright green when wet, white below, lacking distinct rhizines, very loosely appressed and readily removed from the substratum. Photobiont chlorococcoid. Anamorph: Conidiomata pycnidial, immersed, pyriform to almost globose. Conidiogenous cells sessile or on short conidiophores, ± cylindrical. Conidia 4.5-6 × ca 1 μm, bacilliform, hyaline, aseptate, thin- and smooth-walled. Teleomorph: ascomata apothecia, to 1.8 mm diam., initially sessile and often becoming constricted below and short-stalked. Thalline margin prominent, eventually becoming excluded in some apothecia. Disc flat to convex, red-brown to black-brown, the epithecium reddish brown with a clear layer above, N+ green intensifying. Hymenium 60-75(-90) μm tall. Interascal tissue of paraphyses, weakly branched, cellular, the apices widening to ca 3 μm diam. Asci cylindrical to clavate, with a thin outer coat K/I+ blue, the wall and apical dome K/I–, 8-spored. Ascospores 10-13 × (6-)8-10 μm, ellipsoidal, hyaline, aseptate, without a gelatinous sheath or epispore. Chemistry: thallus K–, Pd–.