Opuntia fragilis

Opuntia fragilis, known by the common names brittle pricklypear and little prickly pear, is a prickly pear cactus native to much of western North America as well as some midwestern states such as Illinois, Iowa, Wisconsin and Michigan. It also occurs in several Canadian provinces. It is known from farther north than any other cactus, occurring at as far as 56°N latitude in British Columbia. There is an isolated and possibly genetically unique population in Eastern Ontario known as the "Kaladar population".

Description
Opuntia fragilis is a small, prostrate plant, rarely more than 4 in high: joints tumid, fragile, easily detached, oval, elliptical, or subglobose, 1 - 2 in long and nearly as thick as broad, bright green: areoles 1/4 - 1/2 in apart, with whitish wool and a few white to yellow bristles, which are much longer and more abundant on older joints; spines 1–4, occasionally a few small additional ones, weak, dark brown, the upper one usually longer and stronger than the others, rarely 1 in in length: flowers greenish yellow, 1 - 1+1/4 in wide: fruit ovate to subglobose with few spines or bristles, mostly sterile, 1 in or less long; seeds few and large.

Subspecies and varieties

 * Var. brachyarthra, Coult. A plant with more swollen joints, more numerous and stronger spines, smaller flowers and more spiny fruit Colorado, New Mexico.
 * Var. caespitosa, Hort. Joints bright green, smaller and more crowded than in the type: flowers bright yellow. Colorado.
 * Var. tuberiformis, Hort. Joints olive-green, bulbous-looking. Colorado.
 * Var. tuberiformis, Hort. Joints olive-green, bulbous-looking. Colorado.