Cylindropuntia imbricata
| Light | Full sun; the more the better |
|---|---|
| Water | Sparingly in summer; keep dry in winter, especially where cold and wet combine |
| Soil | Very free-draining, gritty mineral mix (see Soil and potting mix) |
| Temperature | Exceptionally cold-hardy; tolerates hard frost and USDA zones 5–10 |
| Propagation | Cuttings (very easy); also seed |
| Toxicity | Not considered systemically toxic, but the barbed spines and glochids cause painful mechanical injury |
Cylindropuntia imbricata is a large, shrubby-to-tree-like cholla with cylindrical, strongly tuberculate stems and vivid magenta flowers, native to the arid grasslands and deserts of the southwestern United States and northern Mexico. Remarkably cold-hardy for a cactus, it is a mainstay of hardy-cactus and xeric gardens, where it is known variously as tree cholla, cane cholla and walking-stick cholla — the last a nod to the woody, latticed skeletons its dead stems leave behind. It belongs to the genus Cylindropuntia.
Description
Cylindropuntia imbricata grows into a much-branched shrub or small tree, commonly waist- to head-high and occasionally taller, developing a short, gnarled woody trunk with age. The cylindrical green stems are covered in prominent raised tubercles arranged in spiralling ridges — the "imbricate", overlapping pattern that gives the species its name. Each areole bears a cluster of barbed spines loosely sheathed in papery straw-coloured coverings, along with tufts of tiny, irritating glochids typical of the opuntioid cacti.
Showy flowers appear at the stem tips in late spring and early summer, typically deep magenta to purple-pink and several centimetres across, followed by knobbly, yellowish, spineless fruits that persist well into winter. When the plant dies back, the stems rot away to reveal a distinctive hollow, net-like woody cylinder, long collected and sold as decorative "cholla wood".
Distribution and habitat
The species is widespread across the southwestern United States — including New Mexico, Colorado, Texas, Oklahoma and Kansas — and south into the highlands of north-central Mexico. It favours open, sunny country: shortgrass prairie, high desert grassland, rocky slopes and disturbed roadsides, often on gritty or sandy soils. Its tolerance of both intense summer heat and severe winter cold reflects a range that reaches surprisingly high elevations and cold-winter latitudes for a cactus.
Cultivation
C. imbricata is one of the easiest cacti to grow in cold, temperate gardens, and is far more forgiving than most desert species — provided drainage is excellent. Give it full sun and a very free-draining, gritty mix or planting bed. The key to overwintering it outdoors is keeping the roots dry through the cold months; the plant shrugs off hard frost when dry but dislikes the combination of cold and sodden soil. Water occasionally through the warm season and taper off entirely as autumn arrives. See Watering and Repotting for general technique.
A word of caution for gardeners: the barbed spines and glochids detach readily and are genuinely difficult to remove from skin and clothing. Site it away from paths and handle it with thick gloves and folded newspaper or tongs. In some regions it can spread and is regarded as a pasture nuisance, so check that it is welcome before planting.
Propagation
Propagation could hardly be simpler. Like most chollas, detached stem segments root very easily: remove a joint, let the cut surface callus over for several days, then set it on gritty mineral soil and water lightly once rooting begins. This is by far the quickest way to increase the plant. Seed is also viable but slower and less commonly used by hobbyists. See Propagation — cuttings for a full walkthrough, and Propagation — seed for growing from seed.
Common problems
- Rot — the main killer, caused by wet soil in winter or poor drainage rather than cold itself; stems soften, blacken and collapse.
- Glochid and spine injury — not a plant problem but a grower one; the barbed spines and hair-fine glochids embed in skin easily, so handle with care.
- Pests — mealybugs and scale can settle in the areoles, and cochineal scale (white cottony masses) sometimes appears on opuntioid cacti.
See also
- Cylindropuntia — the genus overview
- Propagation — cuttings · Soil and potting mix · Watering · Repotting · Pests and diseases