Opuntia fragilis (Nutt.) Haw.
Gleason, Henry A. & Cronquist, Arthur J. 1991. Manual of vascular plants of northeastern United States and adjacent Canada. lxxv + 910 pp.
Species Description - Prostrate or spreading, forming dense mats to 5 dm wide; joints orbicular to obovate, very turgid, 2–5 × 1–2.5 cm, easily detached; areoles crowded, commonly 3–6 mm apart, usually coarsely white-woolly, all or nearly all armed with (1–)3–7 strongly barbed spines 1.2–2.5 cm; fls yellow to greenish, 4–5 cm wide; fr fleshy and greenish to reddish when young, dry and tan at maturity, inedible, 1.2–1.5 cm; seeds discoid, with an irregular margin; 2n=66. Dry prairies and plains; Ill. and Wis. and n. Mich. to B.C., n. Tex., and Ariz. May–July.
little prickly pear