Parmelia neodiscordans

Parmelia neodiscordans is a species of saxicolous (rock-dwelling) foliose lichen in the family Parmeliaceae. Described in 1987 from Acadia National Park in Maine, this lichen has a limited distribution in eastern North America, occurring primarily at high elevations in the southern Appalachian Mountains but found near sea level in New England, with rare occurrences extending to the Yukon and parts of Canada. The species forms whitish-grey growths up to 8 cm (3 in) across on exposed siliceous rocks and is distinguished by its densely lobulated surface covered with small standing projections, as well as by its chemical composition, which differs from the similar-looking Parmelia discordans with which it was historically confused....read more on Wikipedia.