Stems gray-green. Spines red to gray, infrequently straw colored, canescent. Fruit scales reddish to maroon, aging tan or black, 10-14 mm, usually shorter than dried tepals at fruit apex, spine tips canescent with strap-shaped, unicellular trichomes. Seeds rounded or faceted with flat planes transversing testa, 2.8-4.7 mm, papillate-roughened (exposed surfaces of testa cells protruding, hemispheric to hexagonally faceted, appearing dull except for microscopically sparkling individual facets). 2n = 22.

Flowering Jul-Aug. Rocky flats and washes, bajadas, rock ledges, Mojave and Sonoran desert scrub, igneous and calcareous substrates; [10-]30-1700 m; Ariz., Calif., Nev.; Mexico (Sonora).

REFERENCES: Chamberland, Michael. 1995. Cactaceae Part 2. Echinocacrus. J. Ariz. - Nev. Acad. Sci. 29(1): 13.