Basionym: Mammillaria duwei Rogoz. & P.J.Braun 1985
Publication: Cact. Succ. J. (Los Angeles) 70(2): 94. 1998
Description
Mammillaria scheinvariana is a small plant that forms irregular clumps.
Stem: About 5 cm diameter and 2–3.5cm high. This plant is a member of the Mammillaria crinita complex (Stylothele Series). Only some authors consider M. sheinvariana to be a good species; the others classify it as M. crinita (e.g. Fritz Maurice accepts the individuality of the new plant but considers it a subspecies of M. crinita.)
Radial spines: Numerous hair-like spines give the plant a shaggy appearance.
Central spines: Not usually present, but, if so, they are 9–16 mm long and straight, never hooked. (At first glance the plant has quite a strong resemblance to M. bocasana, but a closer inspection reveals the absence of hooked centrals)
Roots: It has a thick tuberous root system
Flowers: Salmon pink.
Blooming season (Europe): May-June
Origin and Habitat
Zimapan, Queretaro, Mexico
Habitat: The whole habitat of this plant (discovered only in 1997) disappeared under the water of a man-made dam. It is extinct in nature.
Cultivation and Propagation
Mammillaria scheinvariana is an easy species in cultivation.
Growth rate: It is a small growing, but easily flowering species. It takes several years to offset, but once it starts it can fill a 25 cm pot in just a few years given the best conditions.
Soils: It likes very porous standard cactus mix soil with little organic matter (peat, humus).
Repotting: Repotting every 2-3 years. It will need a pot with sufficient depth to allow the tap root. As it is especially prone to rot under-pot in a smaller container filled with very porous compost. Use pot with good drainage.
Watering: Water regularly in summer, but do not overwater (Rot prone), its roots are easily lost in pots that stay damp for any length of time. Keep dry with ample airflow in winter. In the rest period no high atmospheric humidity!!
Fertilization: During the growing season enrich the soil using a fertilizer rich in potassium and phosphorous, but poor in nitrogen, because this chemical element doesn’t help the development of succulent plants, making them too soft and full of water.
Hardiness: Reputedly sensitive to frost , but less so if kept on the dry side prior to, and during, cold weather (hardy to -5° C for short periods, but some reports give it hardy to -12°C). However some warmth throughout the year will increase the grower’s success (minimum 5° to 8°C during rest season).
Exposition: Outside bright sun, filtered sunlight or afternoon shade, inside it needs bright light, and some direct sun. Subject to sunburn if exposed to direct sun for too long. Tends to bronze in strong light, which encourages flowering and heavy wool and spine production.
Uses: It is an excellent plant for container growing. It always looks good and stays small. It look fine in a cold greenhouse and frame.
Pests & diseases: It may be attractive to a variety of insects, but plants in good condition should be nearly pest-free, particularly if they are grown in a mineral potting-mix, with good exposure and ventilation. Nonetheless, there are several pests to watch for:
- Red spiders: they may be effectively rubbed up by misting the vulnerable plants every day
- Mealy bugs: Easily they develop aerial into the new growth among the wool with disfiguring results, but the worst types develop underground on the roots and are invisible except by their effects.
- Sciara Flies: they are one of the major problems for seedlings. It is a good practice to mulch your seedlings with a layer of grit, which will strongly discourage the flies.
- Scales: they are rarely a problem.
It is wise to treat your whole collection with a systemic insecticide twice a year in spring and autumn.
- Rot: it is only a minor problem with mammillaria if the plants are watered and “aired” correctly. If they are not, fungicides won’t help all that much.
Propagation: Direct sow after last frost or (rarely) cuttings. Seeds germinate in 7-14 days at 21-27° C in spring, remove the glass cover gradually as the plants develops and keep ventilated, no full sun for young plants! The seedlings should not be disturbed until they are well rooted, after which they can be planted separately in small pots. Cuttings will take root in a minimum temperature of 20° C (but better in hot weather). Cuttings of healthy shoots can be taken in the spring and summer. Cut the stem with a sharp, sterile knife, leave the cutting in a warm, dry place for a week or weeks (depending on how thick the cutting is) until a callus forms over the wound. Once the callus forms, the cutting may be inserted in a container filled with firmed cactus potting mix topped with a surface layer of coarse grit. They should be placed in the coarse grit only; this prevents the cut end from becoming too wet and allows the roots to penetrate the rich compost underneath. The cuttings should root in 2 to 6 weeks.
Bibliography
Major references and further lectures
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Bill Weightman “Mammillaria sceinvariana submerged” British Cactus and Succulent Journal” Vol 21 (1) 45-48
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ORTEGA-VARELA, R. & GLASS, C. “Guia para la Identificacion de Cactaceas Amenazadas de Mexico. (Identification Guide to theThreatened Cacti of Mexico).” CANTE, A.C., Guanajuato, Mexico.1997
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PILBEAM, J. “Mammillaria” The Cactus File Handbook No. 6. p.260. Cirio Publishing, Southampton, UK. 1999
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FITZ MAURICE, W.A. & B. Cact. Succ. J. (US)70(2): 88-94. 1998
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