The Beavertail Cactus is found in southwest USA, mostly in the Mojave desert and Colorado desert , and also in northwest Mexico. The Beavertail Cactus is a smaller prickly pear cactus growing about 60 cm tall. A single plant may consist of hundreds of fleshy, flattened pads. These are blue-gray, growing to a length of 14 cm and are maximum 10 cm wide and 1 to 1.5 cm thick. They are usually spineless, but have instead small barbed bristles, called glochids, that easily penetrate the skin. The rose purple flowers bloom from spring to early summer.

There is two subspecies and several varieties of this species:

• Opuntia basilaris subsp. basilaris
  • Opuntia basilaris var. albiflorus
  • Opuntia basilaris var. aurea
  • Opuntia basilaris var. brachyclada
  • Opuntia basilaris var. cordata
  • Opuntia basilaris var. heilii
  • Opuntia basilaris var. humistrata
  • Opuntia basilaris var. longiareolata - Elongated Beavertail Prickly Pear
  • Opuntia basilaris var. ramosa
  • Opuntia basilaris var. treleasei - Trelease's Beavertail Prickly Pear, Bakersfield Cactus (California)
  • Opuntia basilaris var. woodburyi
• Opuntia basilaris subsp. whitneyana
  • Opuntia basilaris subsp. whitneyana var. whitneyana

Opuntia basilaris var. treleasei

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 eye-spots contain spines in addition to the bristles; this indicates that the species does vary a lot in its exterior.