Species Native to Missouri
Common Name: plains prickly pear
Type: Herbaceous perennial
Family: Cactaceae
Native Range: United States, northern Mexico
Zone: 3 to 9
Height: 0.50 to 1.00 feet
Spread: 0.50 to 1.00 feet
Bloom Time: June to July
Bloom Description: Yellow
Sun: Full sun
Water: Dry
Maintenance: Low
Suggested Use: Ground Cover, Naturalize
Flower: Showy
Fruit: Showy, Edible
Other: Winter Interest, Thorns
Tolerate: Rabbit, Drought
Culture
Easily grown in dry, sandy or gravelly, well-drained soils in full sun. May be grown in clay soils as long as drainage is good and soils do not remain wet. Tuberous roots. Plants often spread in the wild to form colonies as pads break off and root nearby. Similarly, plants are easily propagated by cuttings: previous year's pads may be severed at the joint during the growing season, dried for a week and then planted directly in the garden (joint wound down) or in a potting medium. May also be grown from seed with moderate difficulty.
Noteworthy Characteristics
Opuntia macrorhiza, a prickly pear cactus, is a clump-forming, semi-prostrate, Missouri native cactus which typically grows 6-14" tall. It occurs over a large geographic range, from Idaho to Wisconsin south to Louisiana and Arizona, but is rare in Missouri where it occurs in certain rocky glades and ledges and rocky open ground in only three counties in the State. It features jointed, round-to-oval, flattened, succulent green pads (4-6" long) which are not leaves but swollen water-storing stem segments. Each pad typically has scattered needle-like spines (1-6 per areole) which are deflexed (turn downward). However, pads are covered with numerous tufts of bristles (glochids) which easily pierce human skin and can cause significant allergic skin reactions. Showy, 2-3" diameter, bright yellow flowers, sometimes with a reddish eye, have 8-12 yellow rays and a bushy clump of yellow center stamens. Flowers bloom in June-July. Pulpy, red fruits (to 2") ripen in late summer to fall and are edible, most often being used to make candies and jams. Native Americans not only ate the fruits (fresh, cooked or dried for winter), but also roasted the pads as a vegetable and used the sap for certain medicinal applications. In autumn, the pads become quite shriveled and begin to lie down as the plants withdraw water in preparation for winter. Though technically evergreen, the plants become quite scraggly in appearance during winter. However, the pads green up quickly in spring. Several descriptive regional common names have been given to this plant, including tuberous-rooted prickly pear, twistspine prickly pear and plains prickly pear. It is similar in appearance to the more common Missouri native prickly pear, Opuntia compressa (syn. Opuntia humifusa), and was once considered to be a variety of this species. Opuntia macrorhiza differs from O. compressa in three main ways: (1) it has thicker tuberous roots as opposed to the fibrous roots of O. compresa, and (2) it tends to have more than one stout spine (up to 6) per areole, and (3) stout spines are deflexed (turn downward).
Genus name comes from the Greek name for a different plant which grew around the ancient town of Opus in Greece.
Specific epithet means with large roots.
Problems
No serious insect or disease problems. Various rots may occur, particularly when plants are grown in soils with poor drainage or too much moisture.
Uses
Rock gardens. Stone walls. Sandy slopes. Dry prairie areas. Small area ground cover.