Epithelantha greggii
| Light | Bright light; a little shade from the harshest afternoon sun |
|---|---|
| Water | Sparingly; let the soil dry fully between waterings, keep dry in winter |
| Soil | Very free-draining mineral mix (see Soil and potting mix) |
| Temperature | Frost-hardy when kept bone-dry (reportedly to around -12 °C); roughly USDA zones 8–11 |
| Propagation | Seed; removal of offsets from established clumps |
| Toxicity | No pet-toxicity data; the genus contains tyramine-type alkaloids (e.g. hordenine), so keep out of reach of pets |
Epithelantha greggii is a larger, often clustering member of the little "button cactus" group, native to the Chihuahuan Desert of Coahuila and Nuevo León in northeastern Mexico. Compared with the tiny type species Epithelantha micromeris, it builds up into broader heads and eventually mounded clumps, and it carries somewhat coarser, less tightly appressed spines — a stouter, more robust take on the same charming woolly-topped design.
Description
Epithelantha greggii forms rounded to shortly cylindrical stems that in time offset freely, producing dense low clusters of many heads. Individual stems are considerably larger than those of the type species — up to about 5 cm or more across — and the plant is entirely clothed in short spines arising from tiny, closely packed areoles. These spines are somewhat coarser and more spreading than the fine, snow-white covering seen in E. micromeris, so the surface often reads as slightly rougher or more shaggy, and the spination can take on chalky white to reddish-brown tones (the synonym E. rufispina points to the reddish-spined forms).
As in the whole genus, the growing point sits under a tuft of wool at the crown, and the small flowers emerge from that woolly apex rather than from the sides of the plant. Blooms are modest and pink — often a shade deeper than those of the type species — and are followed by the slender, elongated bright-red fruits that are so characteristic of Epithelantha.
Distribution and habitat
The species grows in the Chihuahuan Desert of northeastern Mexico, in the states of Coahuila and Nuevo León. Like its relatives it favours limestone — rocky outcrops, gravelly slopes and crevices where drainage is sharp and competition sparse. Plants often grow wedged among rock with only the flat, woolly tops showing, shaded a little by the surrounding terrain and low desert vegetation.
Cultivation
Epithelantha greggii is grown much like the rest of the genus and rewards a careful, dry-leaning routine. Use a very gritty, mostly mineral mix with excellent drainage, and give it bright light — good sun brings out tight, compact growth and keeps the clumps dense. A little shade from the fiercest afternoon sun in a hot greenhouse does no harm.
Water thoroughly only once the soil has dried right out, then hold off; these are slow, xerophytic plants that resent sitting wet, and overwatering is the usual cause of loss. Keep the plant dry through winter, when it will tolerate hard frost so long as it stays bone-dry; a cool, dry rest helps prevent rot and encourages flowering. As a limestone dweller it appreciates a mineral, slightly alkaline substrate — many growers add limestone grit or crushed oyster shell. See Watering and Repotting for general technique.
Propagation
Seed is the primary method: sown on a gritty, mineral surface kept warm and humid, the fine seed germinates readily, though seedlings grow slowly and need patience. Because E. greggii clusters, offsets can also be removed from established clumps and rooted as offsets once any cut surface has calloused. See Propagation - seed for a full walkthrough.
Common problems
- Rot — nearly always from overwatering or a mix that holds moisture; heads soften and discolour, often from the base.
- Etiolation — too little light makes the stems stretch and lose their neat, compact form.
- Pests — mealybugs (white fluff tucked into the wool and among the spines) and red spider mites are the usual offenders; the dense woolly crown can hide early infestations, so inspect regularly. See Pests and diseases.
See also
- Epithelantha — the genus overview
- Epithelantha micromeris — the tiny type species
- Soil and potting mix · Watering · Propagation - seed · Propagation - offsets · Repotting