MAJOR TYPES OF CACTUSES

			COLUMNAR CACTUSES: Have cylindrical stems, with ribs (see pleats) running from bottom to top, that are at least 10x taller than wide. Includes species in the genera Carnegiea (Saguaro), Lophocereus (Senita), Packycereus (Cardon), Stenocereus (Organpipe Cactus), and others) .
			BARREL CACTUSES: Have cylindrical stems, with ribs (see pleats) running from bottom to top, that are less than 10x taller than wide and a have a diameter that is greater than about 5". Flowers grow from top of stem. Includes species in the following genera Ferocactus (Fishhook Barrel) and Echinocactus (Many-headed Barrel).
			HEDGEHOG CACTUSES: Have cylindrical stems, with ribs (see pleats) running from bottom to top, that are less than 10x taller than wide and have a diameter that is less than about 5". Species occuring here are generally less than 12" tall. Flowers grow from sides of stem. Spines are not hooked (as are many pincushion cactuses). Includes species in the genus Echinocereus
			PINCUSHION CACTUSES: Have unbranched cylindrical stems, without ribs (see pleats) running from bottom to top. Species occuring here are less than 6" tall. Central spines are often hooked (unlike hedgehog cactuses). Includes species in the genus Mammillaria (Fishhook Pincushion Cactus).
			CHOLLA CACTUSES: Have branched, cylindrical stems with jointed segments. Includes species in the genus Opuntia (Chainfruit, Christmas, Staghorn, and Teddybear Cholla).
			PRICKLY PEAR CACTUSES: Have flattened, pad-like stems. Includes species in the genus Opuntia (Prickly Pear).