TYPE. UNITED STATES. Maryland, Baltimore County, Gwynns Falls, on rocks, 3.IV.1916, C.C. Plitt s.n. (BP, holotype).
Description. Life form: lichenized fungus.
[Modified from Hinds & Hinds 2007] Thallus foliose, loosely attached, light yellowish-green, 6-20 cm wide; lobes sublinear, separate to imbricate, 1-3 mm wide, dichotomously branched. Upper surface flat, continuous, emaculate. Vegetative diaspores absent. Photobiont chlorococcoid alga. Lower surface brown; rhizines pale brown, simple, 0.5-1 mm long. Ascomata lecanorine apothecia, common, substipitate, 3-15 mm diam.
Chemistry. Cortex with usnic acid (KC+ gold); medulla with salazinic acid (K+ red, PD+ orange).
Substrate and habitat. Saxicolous on rocks.
Distribution. Central and eastern North America; in North Carolina recorded from the Blue Ridge ecoregion.
Hinds, J.W. & P.L. Hinds (2007) The Macrolichens of New England. Memoirs of the New York Botanical Garden No. 96. New York Botanical Garden Press, Bronx, New York. 584 pp.
Lendemer, J.C. (2005) Xanthoparmelia viriduloumbrina, a neglected species from Eastern North America. Mycotaxon 92: 441-442.