Thallus corticolous, elongate, producing numerous, crowded, weakly decumbent or horizontally spreading subimbricate to imbricate branches. Branches flattened with a distinct upper and lower surface, to 5 cm long and 1-2.5 mm wide, margins typically irregular, producing small branchlets or outgrowths, less often margins entire, branching irregular or anisotomic dichotomous. Upper surface green-grey, convex, smooth, basally producing outgrowths over the mazaedium, occasionally transversely cracked, lower surface pale, irregularly wrinkled to lacunose,upper cortex 40-70 µm, lower cortex 20-40 µm. Algal layer 15-25 µm continuous below upper cortex, occurring rarely as isolated groups above lower cortex. Apothecia common, irregular in outline, with minute outgrowths along lower side, 0.4-2 mm wide, subterminal, mazaedium ventral, exposed at an early stage of development, prominent, black, globose at maturity. Asci 45-65 × 5-7 µm. Ascospores spherical, brown, 9-14 µm surrounded with carbonaceous material. Chemistry: K-, Pd+ red. Sphaerophorin and protocetraric acid.