Epithelantha bokei
| Light | Bright light; a little shade from the fiercest afternoon sun |
|---|---|
| Water | Very sparingly; let the soil dry completely between waterings, dry rest in winter |
| Soil | Gritty, fast-draining mineral mix, ideally with added limestone (see Soil and potting mix) |
| Temperature | Keep above freezing; roughly USDA zones 9b–11 |
| Propagation | Seed; occasionally offsets on clustering plants |
| Toxicity | Non-toxic to cats and dogs |
Epithelantha bokei is a small, slow-growing "button" cactus from the Big Bend region of western Texas and adjacent northern Mexico, prized for its chalky-white, almost seamless surface. The tiny spines are so short and so tightly pressed flat against the body that they hide the green flesh entirely, giving the plant the look of a smooth, pale pebble — one of the most refined textures in the whole cactus family.
Description
Epithelantha bokei forms a small, solitary or few-headed globe, usually only a few centimetres across and rarely much taller than it is wide. Like all Epithelantha, the body is built from tiny spiralling tubercles rather than ribs, and each tubercle carries a densely packed cluster of minute white spines. In this species the spines are exceptionally short and lie completely appressed to the surface, so smoothly and evenly that they merge into an unbroken chalky-white skin with no loose or projecting bristles — the trait that separates it at a glance from the more familiar Epithelantha micromeris, whose spines are slightly longer and give a softer, downier look.
Small pale-pink to whitish flowers appear from the woolly crown, opening near the growing tip. They are followed by slender, elongated red fruits that push out from among the tubercles — a cheerful feature on such a subdued little plant. The species was long treated as a subspecies of E. micromeris and is still listed that way by some authorities.
Distribution and habitat
The species is native to the Chihuahuan Desert of the Big Bend country, straddling the Rio Grande between the Texan side and the neighbouring Mexican states. It is a limestone specialist, growing wedged into cracks and gravelly pockets on exposed calcareous hills and ledges, often fully sun-baked and sharing ground with other dwarf cacti and sparse desert scrub.
Because of its restricted range and the demand from collectors, wild plants should never be dug; like the whole cactus family it is covered by CITES Appendix II. Fortunately it is readily raised from seed, so nursery-grown plants are the right — and legal — way to add one to a collection.
Cultivation
Epithelantha bokei is a connoisseur's plant: undemanding in its needs but slow, and quick to rot if kept too wet. Grow it in a very lean, gritty, mostly mineral mix; a little crushed limestone or dolomite suits this lime-loving species well. Give it the brightest light you can, with only light shading from the harshest summer sun, as strong light keeps the body compact and the spine cover dense and white.
Water thoroughly only once the soil has dried right through, then let it dry again, and keep the plant completely dry and cool over winter to prevent rot and encourage flowering. A snug clay pot and careful repotting help avoid moisture sitting around the fine roots. See Watering for general technique. Because it is naturally slow, some growers graft seedlings to build them up faster before returning them to their own roots.
Propagation
Seed is the usual method. The dust-fine seed germinates on a warm, damp mineral surface and is best sown thinly and grown on with patience, as seedlings are tiny and develop slowly. Plants that cluster with age can occasionally be increased by removing offsets, though the species is often solitary. See Propagation — seed and Propagation — offsets for full walkthroughs.
Common problems
- Rot — by far the commonest cause of loss, almost always from overwatering, a slow-draining mix, or water lingering in the crown; the plant softens and discolours from the base.
- Etiolation — too little light makes the body elongate and lose its neat, flattened button shape, and the spine cover looks thinner.
- Pests — mealybugs (white fluff tucked among the tubercles) and red spider mites are the usual offenders on such a small, tight-bodied plant; inspect the crown regularly.
See also
- Epithelantha — the genus overview
- Epithelantha micromeris — the closely related, more widespread button cactus
- Grafting · Soil and potting mix · Watering · Propagation — seed · Propagation — offsets