Any cactus of the genus Opuntia, native to North and South America, having needlelike spines partly enclosed in a papery sheath. Chollas vary greatly in size and have small flowers, sometimes chartreuse and inconspicuous, but usually of more striking colors. O. leptocaulis, the desert Christmas cactus, bears bright red fruits through the winter. Living plants serve as food for desert animals. Cholla wood, a hollow cylinder with regularly spaced holes, is used for fuel and novelties. Some cholla fruit is edible.