n.
Any plant of the genus Opuntia , the largest genus of the cactus family.
Native to the New World, it has characteristic small bristles with backward-facing barbs. Subgroups are based on the form of the stem segments: cholla s have cylindrical joints, while prickly pear s have flat joints. Sizes range from tiny, cold-hardy forms to treelike varieties. In the Northern Hemisphere, opuntia is found farther north than any other cactus.