Description
Columnar plants, usually solitary but they can form pups on old plants. M. spinosissima is very variable due to its wide area of origin in Mexico. The color of the spines vary from red or rust to white. The “rubrispina” selection forms nice clumps of columns, densely spined with bright coppery red spines.
Stem: Cylindrical, dark blue-green, rarely exceeding 30 cm in height, 6 - 7 (10 cm) cm in diameter. Without latex. Parastichy: 13 - 21
Tubercles: Ovate conical, four-sided basally. The axil is slightly woolly.
Radial spines: 20 - 25, white, bristle-like, 4 - 6 mm long.
Central spines: 12 - 15, copper-red, stronger than the radials and thicker at the base, straight, 10 - 12 mm long.
Flowers: Vivid purple/ red to deep pink, 12 mm long and in diameter, encircling the columnar stems.
Blooming season: Late winter and spring,
Fruits: Purplish red or greenish.
Seed: Brown.
Remarks: Mammillaria spinosissima “rubrispina” also known as the “Red-headed Irishman” has very attractive copper/red coloured spines and is one of the most beautiful Mammillarias.
Origin and Habitat
Garden origin (Nursery produced selection)
Cultivation and Propagation
Mammillaria pilcayensis f. rubrispina is an easy to grow cultivar, just as a classic cactus, don’t requires any special treatment, but need as much light as possible without burning the plant to encourage the heaviest spine formation. It is a great starter plant for the cactus grower, that readily builds up into a cluster of stems highlighted by reddish spines, further decorated by rings of purple-pink blooms.
Growth rate: It is a rapidly growing species. It offset from the base and 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. As it is 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 (very wet-sensitively, especially in light of its succulent root system). 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!! Care must be taken with watering as they tends to become swollen and untidy in growth habit if given too much water and shade.
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: It is quite frost resistant if kept dry, hardy as low as -5° C (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.
Traditional uses: The white, hooked spines of this spherical cactus were used as fish hooks in its native Mexico.
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: Sensitive to red spider mite. Overhead watering is helpful in controlling mites.
- Mealy bugs: Occasionally mealy bugs 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.
- Scales: Scales are rarely a problem.
- Rot: Rot it is only a minor problem with cacti 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 (usually) or division . 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: wait until the offsets that appear at the base of old clustered specimens are 1/3 the size of the parent and then detach and plant. 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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Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
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James Cullen, Sabina G. Knees, H. Suzanne Cubey “The European Garden Flora Flowering Plants: A Manual for the Identification of Plants Cultivated in Europe, Both Out-of-Doors and Under Glass” Cambridge University Press, 11/Aug/2011
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David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. “The New Cactus Lexicon” dh books, 2006
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Haustein, Erik “Der Kosmos-Kakteenführer” Franckh-Kosmos 1983
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John Pilbeam “Mammillaria: the cactus file handbook” Cirio Publishing Services Ltd Dec/30,/1999
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Willy Cullmann, Erich Götz, Gerhard Gröner, “Kakteen: Kultur, Vermehrung und Pflege. Lexikon der Gattungen und Arten. Fünfte, völlig neubearbeitete und neugestaltete Auflage.” Stuttgart, Eugen Ulmer Verlag 1984
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N. L. Britton, J. N. Rose “The Cactaceae. Descriptions and Illustrations of Plants of the Cactus Family.” Volume IV, The Carnegie Institution of Washington, Washington 1923
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Ulises Guzmán “Catálogo de cactáceas mexicanas.” Universidad National Autonoma de México, Mexico-State 2007.
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John Pilbeam “Mammillaria The Cactus File Handbook”. cactusfile.com, Southampton 1999
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