Shrubs, forming mats, 15-30 cm. Roots diffuse. Stem segments curved-clavate, gradually to abruptly narrowed at base, 7-19 × 2.5-5 cm; tubercles very prominent, 20-50 mm, 1-3.5 times longer than wide, not or little obscured by spines; areoles 4-6 mm in diam.; wool white to gray. Spines 12-30 per areole, mostly in apical areoles to ± uniformly distributed along stems (in northern populations), spreading, yellow, tan, or red-brown, tipped yellow, longest 3-7 cm; major 3-5 abaxial spines divergent, yellowish or red-brown, angular-flattened, sharp-edged; major (1-)3-5 adaxial spines ascending-divergent, tan or red-brown, angular-flattened to subterete. Glochids adaxial in areole, yellow to brown, 5-7 mm. Flowers: inner tepals yellow, 20-30 mm; filaments yellow to reddish; style cream; stigma lobes cream or tinged pink. Fruits yellow, cylindric to ellipsoid, 40-90 × 14-40 mm, fleshy, spineless (rarely with few very short spines) but usually densely yellow glochidiate; areoles 30-45. Seeds yellowish white to yellow, 5-6 × 3.5-4 mm, smooth. 2n = 44.

Flowering late spring (May-Jun). Chihuahuan and Sonoran deserts, sandy or gravelly desert flats, washes, hills; 700-1200 m; Ariz., N.Mex., Tex.; Mexico (Chihuahua).

PLANT: Mat-formers, low, much-branched, 15-30 cm tall, from fibrous roots.

STEM: segments curved-clavate, gradually to abruptly narrowed at base, 7-19 cm long, 2.5-5 cm in diam.; tubercles very conspicuous, 2-5 cm long.

AREOLES: white- to gray-felty, subcircular, 4-6 mm in diam.

SPINES: mostly in apical areoles to (in northern populations) well distributed along stems, yellow, tan to red brown, yellow-tipped, 12-30 per areole, spreading, the largest 3-7 cm long; major (1-)3-5 apical spines ascending-divergent, tan to red-brown, angular-flattened to subterete; major 3-5 basal spines divergent, yellowish to red-brown, angular-flattened, sharp-edged.

GLOCHIDS: yellow to brown, apical in areole, 5-7 mm long.

FLOWER: inner tepals yellow, 2-3 cm long; filaments yellow to reddish, the anthers yellow; style cream; stigmas cream or tinged pink.

FRUIT: yellow, cylindric to ellipsoid, fleshy, spineless (rarely with a few very short spines) but usually densely yellow-glochidiate, 4-9 cm long, 1.4-4 cm in diam.; areoles 30-45.

SEEDS: yellowish-white to yellow, smooth, 5-6 mm long, 3.5-4 mm wide. 2n = 44.

NOTES: Chihuahuan and Sonoran deserts, sandy or gravelly desert flats, washes, and hills; Cochise, Gila, Graham, Greenlee, Pinal cos.; 750-1200 m (2400-3900 ft); May-Jun; NM, and disjunct and local in Presidio Co., TX; n Chih. in Mex.

REFERENCES: Pinkava, Donald J. 1999. Cactaceae. Ariz. - Nev. Acad. Sci. 32(1).