Thallus lobes variable, narrow, 2-6 mm wide, 0.3-3(-4) cm tall, ± terete or flattened, rarely simple, strap-like, margins entire or variouslynotched and incised, apices rounded, furcate or irregularly pectinate, ± unilaterally thickened, crowded, congested. Surface ± smooth, coriaceous to roughened, scabrid-areolate or furrowed, in humid, low-light sites often ± fenestrate with ragged, lacerate margins, chalky white in subalpine exposed sites, becoming greenish in sheltered, humid or shaded sites, 0.3 mm thick, smoother and more coriaceous in exposed subalpine habitats, 0.05-0.1 mm thick in shade forms. Chemistry: Medulla K+ yellow or -, Pd+ yellow. Two chemodemes appear to be present, a thamnolic acid chemodeme (K+) and a chemodeme with baeomycesic acid (K-).