Plains Prickly Pear

Opuntia polyacantha

Plains Prickly Pear (Opuntia polyacantha) is a low, native cactus that spreads in mats of flat, spiny pads. It blooms in June with big yellow flowers, sometimes peach to red, on dry prairie and rocky slopes around the Black Hills, and the 1986 plant survey of Jewel Cave National Monument lists it.

Free photos from other sources

Plains Prickly Pear: Pale yellow flower with a cluster of yellow stamens, close-up — Opuntia polyacantha. Jack Wander, CC0 1.0. Get it at the source

Plains Prickly Pear: Yellow flower with an orange-red center beside a pink bud — Opuntia polyacantha. Nick Block, CC BY 4.0, resized. Get it at the source

Plains Prickly Pear: Several open pale yellow flowers and pink buds on the pad edges — Opuntia polyacantha. Jack Wander, CC0 1.0. Get it at the source

Plains Prickly Pear: Flowering plant low in prairie grass, pad covered in long pale spines — Opuntia polyacantha. Bonnie Isaac, CC0 1.0. Get it at the source

Plains Prickly Pear: Round pad with long reddish-brown and white spines in dry grass — Opuntia polyacantha. Brian Dickerson, CC0 1.0. Get it at the source

Plains Prickly Pear: Spiny purplish fruit with the dried flower still attached — Opuntia polyacantha. Kallum McDonald, CC0 1.0. Get it at the source

Quick facts
Family	Cactaceae · Cactus
Status	Native perennial
Blooms	June, sometimes from late May into early July
Height	10–30 cm (4–12 in)
Where	Dry, open prairie, rocky slopes and pine-savanna openings in full sun
Also called	Plains Pricklypear, Hairspine Pricklypear, Hairspine Cactus, Prairie Pricklypear, uŋkčéla blaská (Lakota)
Toxicity	The glochids, tiny barbed bristles in every spine cluster, lodge in the skin, where they are hard to find and remove, and cause painful skin and eye irritation.
Traditional use	Sitting Bull College's 1998 Culturally Important Plants of the Lakota says the fruits were eaten raw or dried for later and the pads eaten once the spines were removed, a tea of the pads was taken for diarrhea, and a root tea for urinary trouble.

Roots, seeds & germination

Root: A shallow root system that spreads sideways just under the surface; a clump about 30 cm (1 ft) across can have roots spreading 1.2–1.8 m (4–6 ft) wide. New plants also start where pads touch the ground or break off and take root.

Seed: The fruit is dry and spiny when ripe, about 2–4 cm (¾–1½ in) long, and holds anywhere from none to more than 70 flat, tan to whitish seeds, ripe around September. Animals that eat the fruit or brush against its barbed spines carry the seeds away.

Germination: Slow. The seed coat is hard, and fall-sown seed usually takes about two years to sprout. SDSU notes that carefully filing the seed coat speeds it up. A pad set in sand roots in about three weeks.

How do you identify Plains Prickly Pear?

Look for a low cactus of flat, round to oval pads about 5–12 cm (2–5 in) long that stay firmly attached. Spine clusters cover the whole face of the pad, the longest spines at least 2.5 cm (1 in) and on older pads long, white and hair-like, and each cluster also holds a tuft of glochids, tiny barbed bristles. The flowers are 5–9 cm (2–3½ in) across, with many silky petals, usually yellow but sometimes peach, pink or red, or yellow with a reddish center, and the ripe fruit is dry and spiny. Brittle Prickly Pear has small, thick, egg-shaped pads under about 5 cm (2 in) that snap off at a touch, and shorter spines.

When does it bloom?

June, sometimes from late May into early July.

Where does it grow?

Dry, sunny, open ground: mixed-grass prairie, rocky and gravelly slopes, eroded banks and openings in ponderosa pine savanna, mostly in the foothills and lower elevations around the Hills. The 1986 Jewel Cave survey lists it, NPSpecies lists it at Wind Cave and Devils Tower, and herbarium specimens come from Lawrence, Pennington, Custer and Fall River counties in South Dakota and Crook and Weston counties in Wyoming.