Opuntia ficus-indica system. The plant may be used as an ingredient in adobe to bind and waterproof roofs. "O. ficus-indica" (as well as other species in "Opuntia" and "Nopalea") is cultivated in nopalries to serve as a host plant for cochineal insects, which produce desirable red and purple dyes, a practice dating to the pre-Columbian era. Mucilage from prickly pear may work as a natural, non-toxic dispersant for oil spills. A commercial use for "O. ficus-indica" is for the large, sweet fruits, called tunas. Areas with significant tuna-growing cultivation include Mexico, the Mediterranean Basin, Middle East and northern Africa. The cactus grows
Opuntia basilaris These are more or less blue-gray, depending on variety, long and less than wide and thick. They are typically spineless, but have instead many small barbed bristles, called glochids, that easily penetrate the skin. "Opuntia basilaris" blooms from spring to early summer. The species is variable in nature and several names under different ranks have been described. Only four of these are generally accepted. Some experts consider the Trelease's beavertail to be a full species (Bowen 1987, R. van de Hoek). It is unique among the varieties of "Opuntia basilaris" in that the areoles contain spines in addition to the