Porcupine pricklypear

Opuntia hystricina Engelmann & J. M. Bigelow, Proc. Amer. Acad. Arts 3: 299. 1856; O. erinacea Engelmann & J. M. Bigelow var. hystricina (Engelmann & J. M. Bigelow) L. D. Benson; O. erinacea var. rhodantha (K. Schumann) L. D. Benson; O. erinacea var. xanthostemma (K. Schumann) L. D. Benson; O. rhodantha K. Schumann; O. xanthostemma K. Schumann

Stem segments obovate, 8-10 × 5-8 cm; areoles (6-)8-10 per diagonal row across midstem segment, 10-17 mm apart. Spines in most areoles, grading in size and orientation; longer spines (1-)2-6 per areole, slightly descending porrect, ascending near apex, (yellow-gray to) brown to black, (40-)50-80 mm; smaller spines 4-6 per areole, reflexed, gray-white. Fruits stout; areoles 11-21, bearing 4-8 spines, 4-18 mm. 2n = 44, 66.

Flowering late spring. Grasslands, pinyon-juniper woodlands, clay or limestone soils; 1300-1900(-2400) m; Ariz., Calif., Colo., Nev., N.Mex., Utah.