[Wikipedia] Range, Taxonomy: Opuntia basilaris, the beavertail cactus or beavertail pricklypear, is a cactus species found in the southwest United States. It occurs mostly in the Mojave, Anza-Borrego, and Colorado Deserts, as well as in the Colorado Plateau and northwest Mexico. It is also found throughout the Grand Canyon and Colorado River region as well as into southern Utah and Nevada, and in the western Arizona regions along the Lower Colorado River Valley. One of the first known descriptions of opuntia basilaris come from the reports of the explorations and surveys for a railroad route from the Mississippi River to the Pacific Ocean. This expedition followed the 35th parallel through New Mexico, Arizona, and California. In the 4th volume of this report, The Botany of the Expedition, by George Engelmann and John M. Bigelow, Opuntia basilaris is described as a stout fan shaped opuntia resembling an open cabbage head, with accompanying illustrations. (link added by Mary Ann Machi)