Coryphantha macromeris
| Light | Bright light to full sun; tolerates strong sun once established |
|---|---|
| Water | Moderate in the growing season, allowing the soil to dry between waterings; keep dry in winter |
| Soil | Gritty, fast-draining mineral mix (see Soil and potting mix) |
| Temperature | Notably cold-hardy for the genus: tolerates hard frost when kept bone-dry, to roughly USDA zone 6b–7; in a damp pot keep above freezing |
| Propagation | Seed; division of offsets from clumping plants |
| Toxicity | Not considered a food plant; keep out of reach of pets as a precaution |
Coryphantha macromeris is a clumping cactus of the Chihuahuan Desert, recognised by its unusually long, soft, finger-like tubercles tipped with dark, spreading spines. Mature plants build up into low mounds and produce large, showy magenta to rose-pink flowers in summer, which has made the species a long-time favourite among growers of the genus Coryphantha. It is sometimes sold under the common names Doña Ana cactus, big needle cactus and nipple beehive cactus.
Description
Coryphantha macromeris forms clusters of soft, cylindrical to globular stems, each freely branching from the base so that older plants spread into loose mounds. The defining feature is the tubercle: long, lax and rather flabby compared with most cacti, giving the plant a shaggy, open look rather than a tight geometric one. A groove runs along the upper side of each tubercle, a hallmark of the genus.
Areoles at the tubercle tips carry several stiff, dark central spines surrounded by finer, paler radials; the centrals are often long and slightly curved, and darken with age. In summer the plant bears comparatively large flowers, 4–6 cm across, in bright magenta to rose-pink, often with a darker midstripe and paler margins, opening in the warmth of the day. Small greenish fruits follow.
Distribution and habitat
The species is widespread across the Chihuahuan Desert, from the south-western United States (southern New Mexico and western Texas) into the northern Mexican states such as Chihuahua and Coahuila. It grows on gravelly flats, low hills and desert grassland, typically in gritty, well-drained mineral soils among scattered scrub and grasses that offer a little shelter.
Across much of its range it is a fairly common and adaptable plant. As with all cacti it is listed under CITES Appendix II; nursery-grown plants are widely available and should always be sourced in preference to wild-collected material.
Cultivation
Coryphantha macromeris is one of the easier members of its genus and a good choice for growers who find the smaller, more demanding species tricky. It appreciates more root room and a touch more water than many desert cacti during active growth, but the same rule applies as ever: a very free-draining, mostly mineral mix and no standing wet. Water thoroughly when the soil has dried, then let it dry again; taper off in autumn and keep the plant dry and cool through winter to firm it up and encourage flowering.
Give it strong light — bright sun brings out the best spine colour and keeps the soft tubercles compact rather than lax. Kept bone-dry in winter it is notably cold-hardy for the genus and tolerates hard frost, but a cold, damp pot is the surest way to lose it. See Watering and Repotting for general technique.
Propagation
Because the species clusters so readily, division is the simplest route: an offset detached with a few roots, or an unrooted branch left to callus for a few days, will usually establish quickly on a gritty mix. See Propagation - offsets and Propagation - cuttings.
Seed is the other reliable method and gives the largest, best-rooted plants. Sow onto a warm, mineral surface kept humid until germination; the seedlings are relatively vigorous for the genus. See Propagation - seed for a full walkthrough.
Common problems
- Rot — the usual cause of loss, from overwatering, a slow-draining mix, or wet cold in winter; stems soften and discolour from the base.
- Etiolation — too little light makes the tubercles stretch and flop, exaggerating the naturally soft look and washing out spine colour.
- Pests — mealybugs (white fluff at the areoles and among the tubercles) and red spider mites (fine webbing, bronzed skin) are the main offenders. See Pests and diseases.
See also
- Coryphantha — the genus overview
- Soil and potting mix · Watering · Repotting
- Propagation - seed · Propagation - offsets · Propagation - cuttings