Melanohalea halei

Melanohalea halei is a species of foliose lichen in the family Parmeliaceae. The species was first described in 1966 by the Finnish lichenologist Teuvo Ahti from specimens in eastern North America that had previously been misidentified as Melanohalea olivacea. It is distinguished from similar brown foliose lichens by its yellowish- to greenish-brown colour, a thallus that lies closely against the bark and develops tiny side lobes toward the center, and a medulla that reacts K+ (yellow0 and P+ (red) in standard chemical spot tests. The lichen typically forms roundish patches about 10 cm (4 in) across on tree bark and produces distinctive reddish-brown, cup-shaped fruiting bodies (apothecia) that are usually present on older specimens. Originally known only from the Appalachian region and temperate hardwood forests of eastern North America—where it grows mainly on deciduous trees such as oak, maple, and beech—the species has more recently been recorded from Ontario's Great Lakes region a......read more on Wikipedia.