28. Opuntia aureispina (S. Brack & K. D. Heil) Pinkava & B. D. Parfitt, J. Arizona-Nevada Acad. Sci. 33: 150. 2001.
Opuntia macrocentra Engelmann var. aureispina S. Brack & K. D. Heil, Cact. Succ. J. (Los Angeles) 60: 17, fig. 4. 1988
Shrubs or trees, with short spiny trunks, erect, to 1(-1.5) m. Stem segments not disarticulating, light blue-green to yellow-green, flattened, circular to obovate, 8-12 × 8-12 cm, glaucous, ± tuberculate, glabrous; areoles 6-8 per diagonal row across midstem segment, oblong, 4-5 × 1-3 mm; wool brown to blackish. Spines usually 4-12 per areole, evenly distributed on stem segments, spreading, bright yellow to orange, red-brown at extreme base, aging tan to blackish, not chalky white, acicular; major spines (1-)3-5(-6) per areole, sometimes flattened and/or curved, 20-60 mm; smaller spines 1-7 per areole, slender, to 20 mm. Glochids well spaced in very narrow row encircling areole, subapical tuft not or poorly developed, yellow, unequal in length, to 5 mm. Flowers: inner tepals yellow with orange to red bases, obovate, 30-40 mm; filament yellow to pale green; anthers pale yellow; style yellow, sometimes basally pinkish; stigma lobes green. Fruits green to reddish, turning tan, burlike, 30-40 × 20-25 mm, beginning fleshy, quickly drying, glabrous, bearing several rigid, yellow spines; areoles 12-25. Seeds tan, flattened, irregular in outline, 3-6 mm diam.; girdle protruding to 1 mm. 2n = 22.
Flowering spring (May). Limestone desert flats, low hills; 500-600 m; Tex.; Mexico (Coahuila).
Opuntia aureispina hybridizes with O. phaeacantha (= O. ×spinosibacca M. S. Anthony) and O. macrocentra (= O. ×rooneyi M. P. Griffith).