Nash, T.H., Ryan, B.D., Gries, C., Bungartz, F., (eds.) 2002. Lichen Flora of the Greater Sonoran Desert Region. Vol 1.

Primary thallus: squamulose, persistent; squamules: 2-5 mm long, 1-3 mm wide, entire or irregularly crenate-lobate; lobes: mostly ascending, lower side brownish white; medulla: fairly thin (less than 250 micro meter) podetia: 3-20 mm tall, greenish gray to brown, cup-bearing; cups: 8-12 mm wide, usually simple; margins: entire or with short proliferations surface: corticate or ecorticate, dull, cortex verruculose, breaking into granules or giving rise to isidioid, schizidioid or phyllidioid structures (also occurring in the cup interiors, appearing as appressed squamules) Apothecia: common, up to 8 mm wide, on c. 3 mm long stalks on cup margins, reddish brown to darker ascospores: oblong-ellipsoid, 12-16.5 x 3.5-4.5 micro meter Pycnidia: very common, on cup margins, ovoid, constricted or not at base, with hyaline gelatin conidia: 3.5-9 x 0.5-1.5 micro meter Spot tests: K- or K+ dingy yellowish changing to dingy brown, C-, KC-, P+ red, UV- Secondary metabolite: fumarprotocetraric acid. Habitat and ecology: on soil, especially acidic mineral soil and thin soil over rocks, more rarely over wood, mainly arctic to temperate World distribution: on all continents Sonoran distribution: Arizona, southern California, Baja California, Baja California Sur and Chihuahua. Notes: Cladonia pyxidata is comparable to C. pocillum, but its primary squamules are thinner, more ascending and almost dull, and the lower side is not clearly pure white. The almost stalkless cup of C. pyxidata, which widens gradually from the base, is a diagnostic character. The peltate squamules in the cup interiors of C. pyxidata may also occur in mature specimens of C. chlorophaea, C. dimorpha, C. hammeri and C. pulvinella. However, they are characteristic even in young specimens of C. pyxidata. See also the discussion under C. chlorophaea.