Growing on clacareous rocks. Here are the steps used in the key of the British Flora for the determination of the species: - Thallus small-squamulose; minutely foliose or minutely shrubby with cylindrical lobes; - Thallus heavily wrinkled when dry, thick; - Centre of thallus of loosely interwoven hyphae; - Upper surface matt, dark brown; - On moist rocks.