Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2004. Lichen Flora of the Greater Sonoran Desert Region. Vol 2.
Thallus: crustose, rimose to verrucose areolate to verrucose peltate; prothallus: white areoles: flat to bullate or peltate, thick, opaque or glossy, ecorticate surface: yellowish white to yellowish gray or yellowish orange to orange-white or whitish gray to gray, smooth, white pruinose, with an effigurate margin, or arachnoid, esorediate Apothecia: constricted at the base to almost subpedicilate, 0.5-1.5 mm in diam., lecanorine disc: brown or gray brown, convex; heavily whitish or bluish gray pruinose margin: concolorous with thallus, thin, becoming excluded, even, not flexuose, smooth, entire or verruculose, without a parathecial ring amphithecium: present, with numerous algal cells, with large crystals, insoluble in K, corticate; cortex: distinct, basally thickened, gelatinous or interspersed, hyaline, 15-25 µm thick laterally, 20-50 µm thick basally parathecium: hyaline, containing crystals soluble in K epihymenium: brown to dark brown, with pigment dissolving in K, with crystals dissolving in K hymenium: hyaline, clear; paraphyses slightly thickened (up to 3 µm wide) apically, not pigmented; subhymenium: hyaline, 15-20 µm thick; hypothecium: hyaline, without oil droplets asci: clavate, 8-spored ascospores: hyaline, simple, ellipsoid, 9-14 x 6-7.5 µm; wall: less than 1 µm thick Pycnidia: not seen Spot tests: thallus and apothecia K+ yellow, C+ orange, P+ pale yellow Secondary metabolites: containing atranorin (major), chloroatranorin (minor), eugenitol (minor), roccellic acid (major), sordidone (major). Substrate and ecology: on siliceous rocks under overhangs and on shaded rocks World distribution: bipolar Sonoran distribution: central Arizona. Notes: Lecanora swartzii belongs to the L. rupicola-group is easily recognized by the almost subpedicillate apothecia with a thin margin that becomes excluded, the thick thallus that contains sordidone, and the presence of an amphithecial cortex.