Opuntia polyacantha var. arenaria (Engelm.) B.D.Parfitt
Family: Cactaceae
Opuntia polyacantha var. arenaria image

Stem segments narrowly obovate, 4-7 × 2-3(-5) cm; areoles 4-6 per diagonal row across midstem segment, 8-11 mm apart. Spines in most areoles, of 2 kinds: major spines 1-3 per areole, only in distal 3-9 areoles, reflexed to porrect, brown, longest 20-40 mm; minor spines 5-7 per areole, strongly deflexed, white, 4-7 mm, except middle one to 14 mm. Fruits slender; areoles 10-14, bearing 3-6 spines, to 8 mm. 2n = 22.

Flowering late spring. Sandy barren areas, small dunes; of conservation concern; 1000-1300 m; N.Mex., Tex.; Mexico (Chihuahua).