Mammillaria parkinsonii
| Light | Bright light; a little shade from the harshest afternoon sun |
|---|---|
| Water | Sparingly in the growing season; keep dry and cool in winter |
| Soil | Gritty, fast-draining mineral mix with added lime (see Soil and potting mix) |
| Temperature | Keep above freezing; roughly USDA zones 9b–11 |
| Propagation | Seed, or division of the clustered heads |
| Toxicity | Non-toxic to cats and dogs |
Mammillaria parkinsonii is a clustering cactus from central Mexico, popularly known as the Owl Eye Cactus for the way each stem repeatedly splits into paired heads. As a plant matures it divides dichotomously — one growing point becoming two — so that a well-grown specimen builds into a tight mound of many rounded heads, each crowned with a symmetrical cap of white spines and dense white wool that gives the group its distinctive "owl-eyed" look.
Description
Mammillaria parkinsonii forms cylindrical to club-shaped stems that, rather than offsetting from the base, tend to fork at the apex into two equal heads. Repeated over years, this dichotomous branching produces a domed cluster of tightly packed stems. Each head is covered in conical tubercles arranged in neat spirals, and the axils between them are filled with white wool — sometimes with fine bristles as well.
The areoles carry numerous short, chalk-white radial spines pressed close against the body, and a small number of stouter central spines, often dark-tipped, that stand a little proud of the surface. In late spring and summer the plant produces a ring of small, funnel-shaped flowers near the crown; these are cream to pale yellow, each tepal marked with a pinkish or brownish midstripe, and are usually followed by slender reddish fruit.
Distribution and habitat
The species is native to the semi-arid highlands of central Mexico, where it grows on limestone hills and rocky slopes among sparse scrub. In habitat it roots into gritty, alkaline, mineral-rich ground and endures long dry spells followed by seasonal rains. As a member of Cactaceae, it is listed under CITES Appendix II; nursery-raised plants are widely available and are the only ones that should be bought or traded, as wild collection is both harmful and unnecessary.
Cultivation
Mammillaria parkinsonii is an undemanding and rewarding plant for a sunny windowsill or greenhouse, and its slow build-up of paired heads makes a handsome specimen over time. Grow it in a very free-draining, mostly mineral mix; a little added limestone or crushed oyster shell suits its preference for alkaline ground. Give it bright light with only light shade from the fiercest midday sun to keep the spination dense and white.
Water thoroughly once the soil has dried out through the growing season, then reduce sharply as the days shorten. A cool, completely dry winter rest not only prevents rot but also encourages the ring of spring flowers. See Watering and Repotting for general technique; the dense wool at the crown holds moisture, so avoid overhead watering in cool or still conditions.
Propagation
The species can be raised from seed, which germinates readily on a warm, gritty surface kept lightly humid, and this is the best way to produce large numbers of plants. Mature clusters can also be divided: an individual head, or a small group of heads, can be cut away, the wound left to callus in a dry, shaded spot, and then rooted as a cutting. Because true offsets are less common than apical forking, division is the usual vegetative route rather than pulling offsets.
Common problems
- Rot — the commonest cause of loss, almost always from overwatering, a poorly draining mix, or moisture trapped in the crown wool during cold weather.
- Etiolation — too little light makes the heads stretch and pale, and thins the white spination that is the plant's main attraction.
- Pests — mealybugs love to hide in the woolly axils, and red spider mites can bronze the skin in hot, dry air. See Pests and diseases.
See also
- Mammillaria — the genus overview
- Soil and potting mix · Watering · Repotting · Propagation — seed · Pests and diseases