Opuntia flexispina Griffiths, Bull. Torrey Bot. Club 43: 87. 1916; O. strigil Engelmann var. flexispina (Griffiths) L. D. Benson

Stem segments ovate to subcircular, 20-35 × 15-30 cm, to 1.5 times longer than wide. Spines (0-)1-5 per areole, evenly distributed on stem segments, deflexed sharply (not arching) or recurving laterally, yellow, sometimes with brown basal portions, flexible, the longest 50-80 mm.

Flowering spring. Rangelands, on hills; of conservation concern; 100-200 m; Tex.

Opuntia engelmannii var. flexispina is recognized here reluctantly because it is so poorly known; more study is required to assess its status. Its distribution is limited to Webb and Zapata counties, Texas, according to D. Weniger (1970).