OPUNTIA, the prickly pear or Indian cactus, is a large group, comprising some 25o species, or more, found in North America, the West Indies and South Amer ica, extending as far as Chile. Some have been introduced into Australia with disastrous effects, since they have overrun large tracts of country. They are fleshy shrubs with rounded, woody stems and numerous succulent branches, composed in most of the species of separate joints or parts, which are often much com pressed, elliptic or suborbicular, dotted over in spiral lines with small, fleshy, caducous leaves, in the axils of which are the areoles or tufts of barbed or hooked bristles, usually accompanied by spines. The flowers are mostly yellow or reddish yellow, and are succeeded by pear-shaped or egg-shaped fruits, having a broad scar at the top, mostly furnished on their soft, fleshy rind with tufts of small bristles. The sweet, juicy fruits of several species are much eaten under the name of prickly pears, and these are cultivated for their fruit in Southern Europe, the Canaries and northern Africa.
The cochineal insect (q.v.) is nurtured on the allied Nopalea coccinellifera and sometimes also on species of Opuntia. Planta tions, called nopaleries, are established for rearing this insect, Coccus cacti, and these often contain as many as 50,00o plants. Relatives of Opuntia form 6 other genera.