Notes: Location: 35°12’38.36"N 85°54’0.40"W el. 587 m, Beckwith’s Point Trail.

Substrate and habitat: Growing 2 m above the ground on a slender hardwood tree about 15 cm DBH, in oak-hickory woodland near the rim of a widening canyon, on the western rim of the Cumberland Plateau.

Chemistry:
cortex: UV-
medulla: C- (bleaches the yellow), K-, KC-, Pd-.

Identification: Pyxine sorediata is a fairly circular rosette lichen with rounded, pruinose lobe tips; white borders to the lobes where upper and lower cortex fail to completely connect with each other; and puffy, punctate marginal soralia. Locally at least, the thallus of Pyxine sorediata has a characteristic blue-green aspect, may reach about 8 cm in diameter, and is UV-. The related Pyxine subcinerea, which also occurs here, is more yellow-green and a good deal smaller with a diameter of 2 or 3 cm, and is UV+ bright banana yellow.

References:
Sharnoff’s Pyxine sorediata gallery
CNALH images, description, and locality map, and a larger, interactive locality map.

Voucher specimen:
United States, Tennessee, Franklin County, Sewanee, Beckwith’s Point Trail. 12 Mar 2010. Chris Parrish 0074, det. James C. Lendemer (NY).

Common name: mustard lichen.