Opuntia acanthocarpa Engelmann & Bigelow var. coloradensis L. D. Benson, Cacti Arizona ed. 3, 20, 34, figs. 1.4-1.6. 1969

Trees or sometimes shrubs, with few branches, usually at acute angles. Stem segments ± yellowish green, 10-30 cm; tubercles salient, elongate, (1.5-)2-3 cm. Spines 18-30+ per areole, yellow to light brown, aging dark gray, baggy sheathed; major abaxial spines deflexed to divergent. Flowers: inner tepals bright yellow. Fruits densely spiny; areoles 16-30. 2n = 22.

Flowering spring-early summer (Mar-Jun). Sonoran and Mojave deserts, edges of juniper woodlands, sandy flats, rocky slopes; 400-1200 m; Ariz., Calif., Nev., Utah; Mexico (Sonora).