Description

This variety of the plains pricklypear grows at higher elevations in southeastern California and the Southwest. It is named for its long flexible spines that give the cactus a hairy, grizzled appearance. The several varieties are tetraploid, i.e. they have four chromosomes instead of the usual two. This results in a relatively fast pace of diversification on the evolutionary tree. The old man cactus consequently varies from location to location. Generally, it grows as a low patch of oval pads with dense covering of draping, white spines. Like all cactus, it prefers well-draining soil and little or no water. Although a southern species, old man cactus is quite tolerant of extreme cold. The winter temperatures of SF Bay Area are well within its temperature tolerance.