The Bunny cacti is native to northern Mexico and desert regions stretching into Arizona. This plant has the appearance of a shrub, and spreads out to cover between 2-5 feet of ground as a mature plant. Named for its visual appearance, the Bunny Ear Cactus, also called the Polka-Dot Cactus, has the scientific name of Opuntia microdasys. The spines come off with a simple touch, and are best removed from flesh with tweezers.