Dark Shadow Lichen

Phaeophyscia sciastra, commonly known as the dark shadow lichen or the five o'clock shadow, is a widespread species of foliose lichen in the family Physciaceae. This rock-dwelling species tend to form rosettes on sun-exposed rocks, especially sandstone. The thalli, which grow up to 5 cm (2.0 in) in diameter and are closely attached to their substrate, are made of flat to convex lobes typically up to 0.5 mm wide. The lichen occurs in Africa, Asia, Europe, and North America,...