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.
Opuntia basilaris is a medium-sized to small prickly pear cactus 70–400 mm (2.8–15.7 in) tall, with pink to rose colored flowers. A single plant may consist of hundreds of fleshy, flattened pads. These are more or less blue-gray, depending on variety, 50–210 mm (2.0–8.3 in) long and less than 100 mm (3.9 in) wide and 10–15 mm (0.4–0.6 in) 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.
- Opuntia basilaris var. basilaris (2n=22)
- Opuntia basilaris var. brachyclada (2n=22) - Little beavertail pricklypear
- Opuntia basilaris var. heilii (2n=22) - Heil's beavertail
- Opuntia basilaris var. longiareolata (2n=22) - Elongated beavertail prickly pear or Grand Canyon beavertail pricklypear
- Opuntia basilaris var. treleasei(2n=33) - Trelease's beavertail prickly pear, Bakersfield cactus (This variety is designated as endangered under the federal Endangered Species Act and California Endangered Species Act, which means that killing or possessing it is prohibited in California)
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 bristles; this indicates that the species does vary a lot in its exterior.
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