This section is from the book "A Manual Of Weeds", by Ada E. Georgia. Also available from Amazon: A Manual Of Weeds.
Native. Perennial. Propagates by seeds and by the rooting of broken joints.
Time of bloom: June to August.
Seed-time: July to September.
Range: Minnesota to British Columbia, southward to Utah, Colorado, and Kansas.
Habitat: Dry soil; prairies, rocky foothills.
Plants rather small, partly prostrate, the joints very numerous and breaking away so readily that they often attach themselves to animals by their many spines and are thus transported to new localities. Joints small, only one or two inches long, roundly ovate or club-like, slightly flattened, the fruit-bearing ones rather more compressed. Leaves small, red, awl-like, soon falling away; the tiny protuberances in the axils white-woolly, bearing a cluster of short, grayish-white bristles, becoming stiff and straw-colored as the plants grow old, with usually about four stouter, yellowish-brown spines, a half-inch to an inch long. Flowers pale yellow, nearly two inches broad. Fruit ovate, inedible, prickly, becoming dry at maturity. Seed rather large and thick, with a corky margin. Means of control the same as for the preceding species.
Fig. 202.- Prickly Pear (Opuntia Raphi-nesquii). X 1/6.