Some of the species described here originate in the desert Southwest and Mexico; others are native to those areas and/or to other parts of the western U.S., the Great Plains, Canada, and Florida. Many kinds, with varied appearance. Most species fall into one of two sorts: those having flat, broad joints (pads) or those having cylindrical joints. Members of the first group are often called prickly pear; those in the second group are frequently known as cholla and now placed in the genus Cylindropuntia. Pods that break off and fall to the ground root quickly and hasten the plant's spread. Hardiness is variable, but all require excellent drainage. Flowers are generally large and showy. The fruit is a berry, often edible.
O. cacanapa 'Ellisiana'. ELLISIANA SPINELESS PRICKLY PEAR. Zones MS, LS, CS, TS; USDA 7-11. This spineless prickly pear grows 3 ft. tall and 6 ft. wide in as few as five years. Yellow flowers in August result in showy red fruit in the fall.
O. ficus-indica. PRICKLY PEAR. Zones CS, TS; USDA 9-11. From Mexico. Big, shrubby or treelike cactus to 15 ft. tall, 10 ft. wide, with woody trunks and smooth, flat, green joints with clusters of bristles; few or no spines. Bears yellow to orange, 3- to 5-in.-wide flowers in late spring, early summer. Blossoms are followed by roundish, 2- to 312-in.-long fruit that ripens from yellow to red; these are the prickly pears used in Mexican cooking you may see sold in grocery stores as nopales. Handle them carefully; the bristles break off easily and irritate the skin. Wear rubber gloves when peeling the fruit, or impale it on a fork and carefully strip off skin, avoiding bristly areas. This species is very drought tolerant, but in the hottest regions it will need regular moisture for best fruit.
O. humifusa. HARDY PRICKLY PEAR. Zones US, MS, LS, CS, TS; USDA 6-11. An old Southern favor- ite, native from Canada south to Florida and eastern Texas. Spreading clump grows to 12 in. or less in height, with few-spined, 3- to 6-in.-long pads. Bears yellow, 3- to 4-in.-wide flowers in early summer; 2-in.-long fruit, purple when ripe. Tolerates moister soil than most cacti. Very cold hardy. Good choice for the beach; dry, sunny banks; or containers.
O. lindheimeri. TEXAS PRICKLY PEAR. Zones MS, LS, CS, TS; USDA 7-11. Native to southern Texas. Large, clumping cactus with pads that grow to 1 ft. long and carry 1- to 2-in. spines. Typically 46 ft. tall, but it can reach 12 ft. high and spread even wider. Flowers are yellow, orange, or red, blooming 34 in. wide in late spring or early summer, followed by 2- to 3-in., red-purple fruit.
O. microdasys. BUNNY EARS. Zones CS, TS; USDA 9-11; or houseplant. Native to northern and central Mexico. Grows fast to 2 ft. high, 45 ft. wide (much smaller in pots). Flat, thin, nearly round, velvety green pads reach 6 in. wide; they are set with neatly spaced tufts of short golden bristles, giving a polka-dot effect. 'Albispina' has white bristles. Small, round new pads grow atop larger old ones, giving the plant a silhouette reminiscent of an animal's head. A great favorite with children.
Indoors, site in bright light. In spring through fall, let soil become dry between soakings; every two to three months, apply a general-purpose liquid houseplant fertilizer diluted to half-strength. In winter, water sparingly and stop fertilizing.
O. phaeacantha. Zones MS, LS, CS, TS; USDA 7-11. Native from northern Texas to California. Low, spreading clump (23 ft.), with 4- to 6-in. pads and thick, 2-in. spines. Yellow flowers usually with orange-red centers, 23 in. across, in spring or summer; inch-long red fruit.