Mammillaria pectinifera
| Light | Very bright light with some protection from the harshest afternoon sun |
|---|---|
| Water | Sparingly; allow to dry fully between waterings, kept completely dry in winter |
| Soil | Very free-draining, mostly mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; roughly USDA zones 9b–11 |
| Propagation | Seed (primary); grafting to speed up slow seedlings |
| Toxicity | Non-toxic to cats and dogs |
Mammillaria pectinifera is a small, flat-topped, solitary cactus from the state of Puebla in central Mexico, prized by collectors for the neat comb-like (pectinate) spines that lie pressed flat against each tubercle. The tiny spines fan out along the sides of the body like rows of miniature combs, giving the plant a geometric, almost woven appearance. It was long placed in its own monotypic genus as Solisia pectinata, and is now included in Mammillaria. Wild plants are rare and CITES-protected, though nursery-raised specimens are widely and legally grown.
Description
Mammillaria pectinifera forms a small, low, more or less globular to flat-topped body, usually solitary and only a few centimetres across. The surface is covered in small, closely packed conical tubercles, each bearing an areole with numerous short, white, comb-like spines that press tightly against the body — the feature that gives the plant both its name and its distinctive combed texture. There are no hooked or projecting central spines, so the whole plant feels smooth rather than prickly.
Small funnel-shaped flowers appear near the crown, typically pale pink to whitish with darker midstripes, opening in the cooler part of the growing season. Like many geophytic cacti, the plant sits atop a thickened root and can pull down into the substrate during prolonged drought, leaving little more than the flattened top exposed among the surrounding rock and soil.
Distribution and habitat
The species is native to a restricted area of the state of Puebla in central Mexico, where it grows on arid limestone hills and flats. Plants root in gritty, calcareous soils, often nestled among rocks and low vegetation that offer a little shade and shelter.
Wild populations are limited in extent and have suffered from illegal collection and habitat disturbance. Unlike most cacti, which are covered by the general CITES Appendix II listing for the family, M. pectinifera is listed on the stricter Appendix I, and it is regarded as a species of conservation concern in habitat. Nursery-propagated plants, however, are legal to own and trade; wild collection is not, and there is no reason to seek wild material when seed-grown plants are readily available.
Cultivation
Mammillaria pectinifera has a reputation as a slightly tricky, slow-growing collector's plant, and its main enemy is excess moisture. Grow it in a very free-draining, mostly mineral mix with plenty of grit, ideally with some added limestone or calcareous material to suit its natural chemistry. Give it strong light with just a little protection from the fiercest afternoon sun to keep the body compact and well-coloured.
Water thoroughly only once the soil has dried out completely, then allow it to dry again before the next drink; err on the side of underwatering, especially with young plants. Keep it completely dry and cool through winter, which both prevents rot and encourages flowering. Because the plant naturally retracts on a thickened root, a slightly deeper pot suits it well. See Watering and Repotting for general technique.
Owing to its slow pace, many growers speed up seedlings by grafting them onto a vigorous rootstock, growing them on for a season or two, then returning them to their own roots.
Propagation
Seed is the standard and most reliable method. Sow onto a warm, mineral surface kept humid until germination, then grow the seedlings on carefully with strong light and careful watering. The species is usually solitary and rarely offsets, so vegetative propagation is uncommon apart from grafting to boost early growth. See Propagation — seed and, where offsets do occasionally form, Propagation — offsets.
Common problems
- Rot — by far the commonest cause of loss, almost always from overwatering, a mix that holds too much moisture, or water sitting in the crown; the body softens and discolours.
- Etiolation — too little light makes the plant swell and dome upward, losing its neat flat-topped, combed appearance.
- Pests — red spider mites (fine webbing and bronzed skin) and mealybugs (white fluff among the tubercles) are the usual culprits; see Pests and diseases.
See also
- Mammillaria — the genus overview
- Grafting · Soil and potting mix · Watering · Propagation — seed · Repotting