Cacti are flowering plants with green, fleshy stems which have a waxy coat to retain water. They have spines, as opposed to leaves, and some have glochids, which are tiny barbed bristles. Grand Canyon cacti most commonly have flowers of red, purple or yellow. The majority grow in the inner canyon, although several species are found on the rim. Some of the common catus species found in the park are the California barrel, fishhook, beavertail, desert prickly pear, claretcup hedgehog, Englemann hedgehog, and whipple cholla.