Sclerocactus polyancistrus
| Light | Full sun; strong, direct light year-round |
|---|---|
| Water | Very sparingly; keep dry in winter and through dormancy |
| Soil | Extremely gritty, lean mineral mix (see Soil and potting mix) |
| Temperature | Cold-hardy; tolerates hard frost when bone dry |
| Propagation | Seed (see Propagation — seed) |
| Toxicity | Non-toxic, but heavily armed with rigid hooked spines |
Sclerocactus polyancistrus is a barrel-shaped fishhook cactus of the Mojave Desert, densely clothed in long, hooked red and white spines and crowned in spring with large, showy magenta flowers. Commonly called the Mojave fishhook cactus or hermit cactus, it is one of the most striking and most challenging members of the genus Sclerocactus, prized by collectors for its fierce armament and vivid blooms.
Description
Sclerocactus polyancistrus forms a solitary, cylindrical to barrel-shaped body, typically taller than it is wide and reaching a foot or more in age, though it is usually much smaller in cultivation. The stem is almost entirely hidden beneath a dense cage of spines. Each areole bears numerous straight white radial spines and several longer central spines, some flattened and reddish to purple-brown, at least one of which is strongly hooked at the tip — the "fishhook" that gives the plant and its genus their name.
The flowers appear in spring, emerging near the crown: large and funnel-shaped, in bright magenta to reddish-purple, they are among the showiest in the genus and open over a succession of sunny days. Fruits are small, dry and thin-walled, releasing dark seeds as they split.
Distribution and habitat
The species is native to the Mojave Desert of the southwestern United States, chiefly in California and Nevada, where it grows on dry, open slopes, gravelly flats and desert scrub. It favours coarse, sharply drained mineral soils and endures a punishing climate of intense sun, low rainfall, hot summers and cold winter nights.
Like most slow-growing desert cacti, wild plants are vulnerable to illegal collection and habitat disturbance, and — as with the whole cactus family — the genus is listed under CITES. Nursery-grown, seed-raised plants are the responsible source; plants should never be dug from the wild.
Cultivation
Sclerocactus polyancistrus has a reputation as a difficult plant, and it rewards growers who respect its desert origins. The keys are ferociously sharp drainage, strong light and a genuinely dry winter rest. Grow it in a very lean, gritty, mostly mineral mix — even more open than for most cacti — in a deep pot that accommodates its taproot, and site it in the brightest, sunniest position available.
Water is the great danger. Give occasional thorough soakings only during the active growing period, always allowing the soil to dry out completely in between, and keep the plant bone dry from autumn through winter. Kept dry, it is remarkably cold-hardy and tolerates hard frost; kept damp and cold, it rots quickly. Many growers find it more forgiving on its own deep roots in a mineral substrate than in rich, moisture-retentive compost. See Watering and Repotting for general technique, and handle with care — the hooked spines catch skin and clothing readily.
Propagation
Propagation is almost exclusively from seed, as the species is solitary and does not offset. Sow on a gritty, well-drained surface; germination can be erratic and seedlings grow slowly, so patience is essential. A cold period before sowing can improve germination for this cold-desert species. Some growers graft seedlings onto a hardier rootstock to speed early growth and reduce losses, later establishing them on their own roots. See Propagation — seed for a full walkthrough.
Common problems
- Rot — by far the commonest cause of death, from overwatering, a soil that holds moisture, or any dampness during the winter rest.
- Loss of roots — the fleshy taproot resents stagnant conditions; a lean mineral mix and a deep pot help it stay healthy.
- Etiolation — too little light produces soft, pale, uncharacteristic growth in a plant built for blazing desert sun.
- Pests — mealybugs (including root mealybugs) and red spider mites can trouble stressed plants; inspect the crown and roots regularly.
See also
- Sclerocactus — the genus overview
- Grafting · Soil and potting mix · Watering · Propagation — seed · Repotting