Astrophytum ornatum
| Light | Bright light; tolerates and colours up in strong sun, more than most of the genus |
|---|---|
| Water | Moderate in growth, allowing the mix to dry between waterings; keep dry and cool in winter |
| Soil | Fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; roughly USDA zones 9b–11 |
| Propagation | Seed (primary); grafting to speed seedling growth |
| Toxicity | Non-toxic to cats and dogs |
Astrophytum ornatum is the largest, most columnar and most heavily armed member of the genus Astrophytum, native to central Mexico. It carries sharp yellow-brown spines and bands of silvery flecking that are typically arranged in decorative, oblique spirals up the body, giving it a strikingly ornamental look — hence the species name.
Description
Astrophytum ornatum begins life globular but, unlike its rounder relatives, elongates with age into a tall column that can reach well over a metre in cultivated old specimens. The body is a deep green, usually clothed in the silvery-white trichome flecking characteristic of the genus; in this species the flecks tend to line up into diagonal bands or spirals rather than scattering evenly, one of its most recognisable features. There are usually eight prominent ribs bearing woolly areoles, from which emerge stout, sharp, radiating spines in shades of yellow to amber-brown that darken with age. As with the rest of the genus, the flowers are large, funnel-shaped and glossy yellow, opening from the crown on plants of flowering size. It is the most heavily spined Astrophytum, standing in clear contrast to the near-spineless Astrophytum asterias and Astrophytum myriostigma.
Distribution and habitat
The species is endemic to central Mexico, where it grows on rocky slopes and cliffs in arid to semi-arid scrub, often rooted into crevices in mineral, well-drained ground. It is among the more widespread and robust members of the genus in habitat, and is very widely propagated in cultivation.
Cultivation
Astrophytum ornatum is one of the easier and more forgiving members of the genus, which makes it a good introduction to Astrophytum for a keen grower. Give it the brightest position you can — it takes more direct sun than the flatter species and rewards it with stronger spination and denser flecking. Plant in a gritty, fast-draining mineral mix and use a pot that dries out reasonably quickly. During the warm growing season water moderately, letting the mix dry between waterings (see Watering); as autumn arrives, taper off and keep the plant dry and cool through winter to encourage a proper dormancy and, in time, flowering. It is more vigorous and faster-growing than most of its relatives, so mature plants may need occasional repotting into a taller pot to accommodate the columnar habit. Protect from frost.
Propagation
Propagation is chiefly by seed, which germinates readily and is the standard way to raise this species. Growers in a hurry sometimes speed seedlings along by grafting them onto a vigorous stock, then growing them on their own roots later, though ornatum is robust enough that this is less necessary than with the slower, fussier species.
Common problems
- Rot — the usual killer, caused by too much water, a mix that holds moisture, or watering during cold, dark spells. Keep the medium gritty and err on the dry side, especially in winter.
- Etiolation — grown too dark or too warm and wet, plants stretch, pale and produce weaker spines; the diagnostic banded flecking also shows best in strong light.
- Pests — watch for mealybugs in the areoles and on the roots, and for red spider mite in hot, dry, still air.
See also
- Astrophytum — the genus overview
- Astrophytum asterias · Astrophytum myriostigma · Astrophytum capricorne — related species
- Grafting · Soil and potting mix · Watering · Propagation — seed