Opuntia engelmannii
| Light | Full sun; very tolerant, colours up best in bright light |
|---|---|
| Water | Sparingly once established; drought-hardy, keep dry in cold winters |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Notably cold-hardy for a prickly pear; withstands hard frost when kept dry, especially planted in the ground; give potted plants more protection from prolonged deep freezes |
| Propagation | Pad cuttings (easiest); also seed |
| Toxicity | Not chemically toxic, but glochids and spines cause serious mechanical injury |
Opuntia engelmannii is a large, clumping prickly pear widespread across the American Southwest and northern Mexico, where it forms broad, sprawling thickets of blue-green to green pads topped with showy yellow flowers in spring. Named for the 19th-century botanist George Engelmann, it is one of the most common and variable prickly pears in its range, and goes by the common names Engelmann's prickly pear and cactus apple. It belongs to the genus Opuntia.
Description
Opuntia engelmannii is a shrubby, mound-forming cactus that typically grows knee- to shoulder-high and spreads outward into dense clumps several metres across. The stems are built from flattened, roughly circular to oval pads (cladodes), green to blue-green, that branch freely to create the plant's characteristic broad, layered silhouette.
Each pad carries widely spaced areoles bearing stout spines — usually whitish to yellowish, and variable in length and number — along with tufts of tiny, barbed glochids that detach at the slightest touch. In late spring the plant produces large, cup-shaped flowers, most often bright yellow (sometimes ageing to orange or flushed with red), followed by fleshy, deep purple-red fruits known as tunas. The species is notoriously variable across its range, and botanists recognise several varieties differing in pad size, spine colour and habit.
Distribution and habitat
The species ranges widely across the southwestern United States — including Texas, New Mexico, Arizona and California — and south into northern Mexico. It grows in deserts, grasslands, thornscrub and rocky slopes, from low desert flats up into foothills, tolerating a broad span of soils and elevations.
It is a keystone plant of many Southwestern landscapes: the pads and fruits are browsed by javelina, deer, tortoises and countless birds and rodents, and the clumps provide shelter and nesting sites. The purple tunas have long been gathered and eaten by people of the region.
Cultivation
Opuntia engelmannii is an easy, vigorous grower for anyone with room and full sun. Give it a gritty, sharply draining mix and a bright, open position; it colours and flowers best in the strongest light. Once established it is highly drought-tolerant and needs little supplemental water, though occasional deep soaks in the growing season encourage fuller pads and better flowering. Keep it on the dry side through cold spells, as wet, freezing conditions are far more damaging than cold alone.
In the ground it can become very large and wide, so site it where its spreading habit and formidable spines will not be a nuisance along paths. Handle with thick gloves and tongs: it is the fine glochids, more than the big spines, that cause the most trouble. See Repotting for moving container plants.
Propagation
By far the simplest method is pad cuttings. Detach a healthy pad at the joint, let the cut surface callus over for a week or more in a dry, shaded spot, then set it upright in gritty mix and water only sparingly until roots form. The species also grows readily from seed cleaned from the ripe fruit, though seedlings are slower and more variable. See also Propagation — offsets.
Common problems
- Rot — from waterlogged soil or wet, freezing conditions; pads soften, discolour and collapse.
- Glochid injury — the hair-like glochids lodge in skin easily and are hard to remove; always handle with care.
- Pests — cochineal scale (white cottony masses on the pads) is common on Opuntia, along with the usual mealybugs; see Pests and diseases.
- Sunburn on soft growth — plants moved suddenly from shade to full sun can scorch, though established plants are extremely sun-tolerant.
See also
- Opuntia — the genus overview
- Propagation — cuttings · Soil and potting mix · Watering · Pests and diseases · Repotting