Coryphantha echinus
| Light | Bright light; full sun once established, with a little shade for young plants |
|---|---|
| Water | Sparingly in the growing season; keep dry and cool in winter |
| Soil | Very free-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep dry in winter; tolerates hard frost when bone dry, USDA zones 8b–10 |
| Propagation | Seed (primary); rarely offsets |
| Toxicity | Non-toxic to cats and dogs |
Coryphantha echinus is a small, usually solitary cactus of the Chihuahuan Desert, native to western Texas and adjacent northern Mexico. Its globe- to short-cylinder-shaped body is almost completely hidden beneath a dense armour of radiating, interlacing spines, giving it the bristling look of a sea urchin and the common name sea urchin cactus. Bright, glossy yellow flowers open from the woolly crown in the warmth of summer.
Description
Coryphantha echinus forms a firm, spherical to slightly elongated body only a few centimetres across, typically growing alone rather than clustering. Like all Coryphantha, its surface is built from prominent conical tubercles rather than continuous ribs, and each tubercle carries a woolly, grooved areole from which the spines radiate.
The spination is the plant's defining feature: numerous slender radial spines press flat against the body and interlace with those of neighbouring tubercles, while one or a few stouter central spines project outward. The overall effect is a tight, star-burst covering that all but conceals the green skin beneath. Flowers appear at the crown in summer, opening a clear yellow, sometimes with a paler throat, and last only a few days each. They are often triggered by warmth following rain.
Distribution and habitat
The species is native to the Chihuahuan Desert, ranging across the Trans-Pecos region of western Texas and into the neighbouring Mexican states. It favours exposed limestone hills, rocky slopes and gravelly flats, where plants nestle among rock and low desert vegetation in thin, sharply drained soils. In this open habitat it endures intense sun, seasonal drought and considerable swings between hot days and cold nights.
Like the entire cactus family, Coryphantha echinus is listed under CITES Appendix II, which governs international trade. Nursery-propagated plants are the responsible source for collectors; wild specimens should never be dug.
Cultivation
Coryphantha echinus is a good desert-cactus subject for a grower who can resist overwatering, which is the main cause of loss. Plant it in a very gritty, mostly mineral mix in a pot that drains freely, and give it as much light as you can — it colours and spines best in strong sun, though young plants appreciate a little shade at first.
Water thoroughly during warm weather only once the soil has dried right out, then allow it to dry again before the next drink. Through winter keep the plant completely dry and cool; this rest both protects it from rot and encourages the summer flush of flowers. Kept dry, it is notably cold-tolerant and withstands hard frost, but wet cold quickly causes rot. See Watering and Repotting for general technique.
Propagation
Seed is the standard and most reliable method. Sown on a warm, gritty surface and kept humid until they sprout, the seedlings grow slowly but steadily. Because the species is usually solitary and seldom offsets, vegetative propagation is uncommon; when clustering forms do appear, offsets can occasionally be separated and rooted. See Propagation — seed and, where applicable, Propagation — offsets.
Common problems
- Rot — nearly always from overwatering or a mix that holds moisture; the body softens and discolours from the base.
- Etiolation — too little light produces weak, elongated growth and sparse spination, spoiling the compact form.
- Pests — mealybugs (white fluff tucked among the tubercles and roots) and red spider mites are the usual offenders; see Pests and diseases.
See also
- Coryphantha — the genus overview
- Soil and potting mix · Watering · Propagation — seed · Repotting