Jordan, W.P. (1973) The genus Lobaria in North America north of Mexico. The Bryologist 76(2): 225-251.
Description, p. 237 (modified)
Thallus up to 14 cm broad, firmly attached, coriaceous, strongly scrobiculate, rarely ribbed or smooth; Water Green to Primrose Yellow or Olive-Buff when dry, blackish when wet. Lobes often imbricate or ascending, rounded or less commonly elongate, up to 2 cm wide, tips often strongly pulverulent. Margins subentire or strongly undulatecrenate, rarely with scattered hairs, not thickened except where sorediate. Soredia on lamella and margins, becoming dark brown; soralia punctiform, becoming confluent or linear on margins. Lobules and isidia absent. Lower surface smooth or rugose, not distinctly veined, densely tomentose with scattered small naked areas. Young areas Cartridge Buff, Chamois and much darker in older areas. Tomentum often blackening, present to margins; rhizines often abundant, present in clusters, to 3 mm or more in length.
Thallus thickness 250-400, wrinkles to 500t. Upper cortex with irregular surface, outer part brownish, 34-57t thick, of 5-9 cell layers, lumen usually 5 but up to 8t diam. Algal layer thick and irregular, occasionally interrupted, 45-100t thick; algae bluegreen, 3-7/t diam., arranged in tight clusters. Medulla 100-220 μm thick, to 300 μm thick in wrinkles; hyphae ca. 51 μm thick. Lower cortex 28-451 μm thick and paraplectenchymatous in rhizinate areas, thinner and subparaplectenchymatous in naked areas, 4-6 cells thick, lumen to 6 μm diam., brownish. Tomentum hyaline, unbranched, up to 2001 μm long and grading into rhizines, 51 μm wide. Cephalodia absent.
Pycnidia unknown. Apothecia rare and when occurring, often parasitized, lamellar, scattered, sessile to short stipitate, to 1.5 mm broad. Disc flat, becoming irregular and convex, Morocco Red and darkening. Thalline exciple strongly papillate, with or without algae, 113 μm thick, rim smooth and becoming wavy. Hymenium 100-120 μm thick, pale brownish, epithecial gelatin orange-brown. Hypothecium ca. 70 μm thick, yellowish brown, cells indistinct. Paraphyses thread-like, ca. 2 μm diam. Asci 92-108 x 16-20 μm; spores 8 per ascus, hyaline, 1-3 septate, acicular, straight or curved, ends often asymmetrical, 61-72 x 6-8 μm.