Type. UNITED STATES. MAINE, Cumberland County, Brunswick, Prince's Point near Brunswick, Arcadia Inn, on a small conif. tree, 1939-08-28, G.B.F. Degelius s.n. (FH, 00472026)
Description. Lichenized fungus.
Thallus foliose, pale gray, spotted with white maculae; lobes thin, appressed to somewhat ascending, 0.3-1.0(-2.0) mm wide, margins and tips finely divided and dissolving into granular soredia; lower surface white with pale rhizines. Ascomata lecanorine apothecia, absent to abundant, < 1 mm diam.; disk dark brown, often pruinose.
Substrate and Habitat. On exposed bark in forest canopies as well as in human altered habitats.
Distribution. Eastern North America; in North Carolina throughout.0
Notes. A very common lichen, Physcia millegrana has been described as the most pollution-tolerant macrolichen in eastern North America (McCune 2000), found dominant in urban settings (e.g., Perlmutter 2010).
Brodo, I.M., S.D. Sharnoff & S. Sharnoff. (2001) Lichens of North America. New Haven: Yale University Press. 725 pp.
Degelius, G. (1940) Contributions to the lichen flora of North America. I. Lichens from Maine. Arkiv før Botanik.30A(1): 1-62 (original description).
McCune, B. (2000). Lichen communities as indicators of forest health. The Bryologist103(2): 353-356.
Perlmutter, G.B. (2010) Bioassessing air pollution effects with epiphytic lichens in Raleigh, North Carolina, U.S.A. The Bryologist113(1): 39-50.