|This green, upright, cactus grows to 12 feet in height and has hairy cylindrical joints to 5 inches in length. The 4 or more yellow spines reach up to 7/8 inch in length, guarding its body. In summer the bell-shaped, large flowers are borne singly on the edge of the pads, and stem tips and then produce fruit. This genus has the largest membership of sun loving species. Australia has even banned a few because of their rapid growth.