Engelmann & J. M. Bigelow, Proceedings of the American Academy of Arts and Sciences 3: 291, 1856
What is Opuntia occidentalis?
Opuntia occidentalis is a prickly pear cactus that occurs in southern California. Britton and Rose reported that the type locality is the “western slopes of the California Mountains,” between San Diego and Los Angeles. The cactus also occurs on the islands off the California coast.
O. occidentalis is a large prickly pear (up to 1.2 m tall) with similarities to O. engelmannii. It may form large single-species thickets. Cladodes are typically obovate, blue-green, 20 cm wide and up to 30 cm long, but they may be larger or smaller. Dark red-brown spines are typical, but they may be pale at the tips.
Flowers are yellow but may have reddish tints. Fruit is reddish-purple, occasionally green, and sweet. Seeds are larger than in the similar O. engelmannii.
O. occidentalis is hexaploid.