Shrubs, low, 10-25 cm, with ± prostrate branches. Stem segments not easily detached, green, elliptic to narrowly to broadly obovate to circular, 4-27 × 2-18 cm, low tuberculate; areoles 4-14 per diagonal row across midstem segment, subcircular, 3-6 mm; wool tan to brown. Spines at all or only distal areoles of stem segment, terete to flattened, stout to acicular to bristlelike, straight to curling, of 1 or 2 kinds; if 1 kind: 0-18 per areole, spreading and curling in various directions, sometimes straight, erect, ascending to deflexed, yellow to dark brown to black, turning gray, pink-gray to gray-brown, longest (35-)40-90(-185) mm; if ± 2 kinds: major spines (0-)1-5, reflexed to porrect, yellow-brown to brown to gray, longest 20-150 mm; minor spines (0-)5-11, deflexed, white to white-gray, longest 4-16 mm. Glochids inconspicuous, in narrow, tidy crescent at adaxial edge of areole or in broad, brushy crescent and tuft, yellow to reddish, aging brown, to 10 mm. Flowers: inner tepals yellow to magenta throughout, 25-40 mm; filaments white, yellow, or red to magenta (flowers may superficially appear bicolored); anthers yellow; style white to pale pink; stigma lobes green. Fruits tan to brown, ± cylindric, 15-45 × 12-25 mm, dry at maturity, glabrous, sometimes burlike; areoles 10-33, each or only distal areoles bearing 3-16 spines, 4-20 mm. Seeds tan to gray, flattened, warped, oblong to subcircular, 3-7 × 2-4 mm; girdle protruding 1-2 mm. Populations of Opuntia polyacantha with spines few or absent (especially var. hystricina) were the basis for several names including O. juniperina, O. utahensis, and O. rhodantha.

Plant: Shrubs low, with ± prostrate branches, 5-50 cm tall. PADS green, glabrous, the terminal ones not easily detached, elliptic, narrowly to broadly obovate to circular, (4-)6-27 cm long, 2-18 cm broad. AREOLES 4-14 in a row diagonal across midpad, subcircular, 3-6 mm in diameter; wool tan to brown Leaves: SPINES at all to only distal areoles of pad, either of one kind: 1) not separable into major and minor spines, yellow to dark-brown to black turning gray, pink-gray to gray-brown, (0-)1-18 per areole, the largest (3.5-)4-9(-18.5) cm long and spreading and curling in all directions to ± straight, erect, ascending to deflexed or 2) of ± two kinds: major spines yellow-brown to brown to gray, reflexed to porrect, 1-5, the largest 2-15 cm long; minor spines white to white-gray, deflexed, 5-11, the largest 0.4-1.6 cm long. GLOCHIDS yellow, aging brown, in crescent at areole apex, 1-5 mm long Flowers: inner tepals yellow to magenta, 2.5-4 cm long; filaments white, yellow to magenta; style white to pale pink; fresh stigmas green Fruit: FRUITS tan to brown, dry at maturity, 1.5-4.5 cm long, 1.2-2.5 cm in diameter; areoles 10-33, each or only the uppermost bearing 3-16 spines, 4-20 mm long, sometimes bur-like. SEEDS tan to gray, oblong to subcircular, 3-7 mm long, 2-4 mm wide; girdle protruding 1-2 mm. REFERENCES: Pinkava, Donald J. Cactaceae. 2003. J. Ariz. – Nev. Acad. Sci. Volume 35(2).