Mammillaria duwei
| Light | Bright light with some protection from harsh summer sun |
|---|---|
| Water | Sparingly; allow to dry fully between waterings, keep dry in winter |
| Soil | Very free-draining mineral mix (see Soil and potting mix) |
| Temperature | Keep above freezing; frost-tender |
| Propagation | Seed (primary); offsets from older clustering plants |
| Toxicity | Non-toxic to cats and dogs |
Mammillaria duwei is a small, soft-bodied cactus from central Mexico, prized by collectors for its cushion of fine, whitish, interlacing spines and its relatively large, yellow to cream flowers. Despite the modest size of the body, the delicate spination and generous blooms give it a charm out of proportion to its dimensions, and it is one of the more sought-after miniatures in the genus Mammillaria.
Description
Mammillaria duwei forms a low, soft, flattened-globular body only a few centimetres across, usually solitary when young but slowly clustering with age. The stem is soft to the touch — unusually so for the genus — and clothed in numerous fine, whitish radial spines that interlace and press close to the body, partly veiling the green stem beneath. At each areole there are also one or two short, yellowish central spines with a slightly hooked tip, though the plant's soft overall look comes chiefly from the dense mesh of pale radials.
The flowers are fairly large relative to the plant, yellowish, cream to bright yellow, and open in a ring around the crown; against the pale spination they make for a striking little display. Small fruits and seed may follow.
Distribution and habitat
The species is native to the highlands of central Mexico, in the state of Guanajuato, where it grows on volcanic rock among low, arid scrub at roughly 1,750–2,000 m elevation. Like many small Mexican cacti, it experiences a warm growing season with summer rains and a cool, dry winter, and the plants often sit tucked among rocks and shrubs that give a little shade and shelter.
The species is endemic to a single known locality and is assessed as Critically Endangered on the IUCN Red List, with perhaps only around 500 mature plants surviving in the wild; illegal collection for the specialist trade is a principal threat to it. As with the whole cactus family, it is also listed under CITES Appendix II. Nursery-raised plants are the proper and legal source for collectors; wild collection is neither necessary nor permitted.
Cultivation
Mammillaria duwei is a rewarding miniature but, like most soft-bodied members of the genus, it is sensitive to excess moisture at the roots. Grow it in a very free-draining, largely mineral mix in a small pot, in bright light with a little shielding from the most intense afternoon sun in summer. Water thoroughly only once the soil has dried out completely, then allow it to dry again; keep the plant dry and cool through winter, which both prevents rot and encourages the following season's flowers. See Watering and Repotting for general technique.
Some growers find the species easier and faster on a graft, though it grows perfectly well on its own roots given a gritty mix and restraint with the watering can.
Propagation
Seed is the usual and most reliable method, sown on a warm, mineral surface kept lightly humid until germination. Older plants that have begun to cluster can also be increased by carefully removing rooted offsets. See Propagation — seed and Propagation — offsets for full walkthroughs.
Common problems
- Rot — the most frequent cause of loss, almost always from overwatering or a mix that holds too much moisture; the soft body discolours and collapses from the base.
- Etiolation — too little light makes the body stretch and pale, spoiling its compact form.
- Pests — red spider mites (fine webbing and a bronzed look) and mealybugs (white fluff among the spines and in the crown) are the usual offenders. See Pests and diseases.
See also
- Mammillaria — the genus overview
- Soil and potting mix · Watering · Propagation — seed · Propagation — offsets · Grafting