Origin and Habitat: Federal states of Mexico and Guerrero (Barranca de Pilcaya, Barranca de Malinaltenango), Mexico.
Altitude range: 600-1.500 metres above sea level.

• Mammillaria spinosissima subs. pilcayensis (Bravo) D.R.Hunt
• Mammillaria pilcayensis Bravo

• Mammillaria spinosissima subs. pilcayensis (Bravo) D.R.Hunt
• Mammillaria pilcayensis Bravo
• Mammillaria pilcayensis var. chrysodactyla Appenz.
• Mammillaria chrysodactyla Appenz.

• Mammillaria spinosissima Lem.
• Cactus spinosissimus (Lem.) Kuntze
• Neomammillaria spinosissima (Lem.) Britton & Rose
• Mammillaria centraliplumosa Fittkau
• Mammillaria centraliplumosa var. gracilis Repp.
• Mammillaria gasterantha Repp.
• Mammillaria haasii J.Meyran
• Mammillaria hermannii var. flavicans Salm-Dyck
• Mammillaria pitcayensis Bravo
• Mammillaria pretiosa var. cristata Hildm. ex C.F.Först.
• Mammillaria spinosissima var. auricoma f. cristata hort.
• Mammillaria spinosissima var. aurorea (Ehrenb.) Gürke
• Cactus auroreus Kuntze
• Mammillaria aurorea Ehrenb.
• Mammillaria spinosissima brunnea Salm-Dyck
• Mammillaria spinosissima f. brunnea (Salm-Dyck) Gürke
• Mammillaria spinosissima var. castaneoides (Lem.) Borg in Borg
• Mammillaria castaneoides Lem.
• Mammillaria spinosissima f. cristata
• Mammillaria spinosissima var. eximia (Ehrenb.) Gürke
• Cactus eximius (Ehrenb.) Kuntze
• Mammillaria eximia Ehrenb.
• Mammillaria spinosissima f. eximia (Ehrenb.) Schelle
• Mammillaria spinosissima var. flavida Salm-Dyck
• Mammillaria spinosissima f. flavida (Salm-Dyck) Gürke
• Mammillaria spinosissima var. genuina Gürke
• Mammillaria spinosissima var. haseloffii (Ehrenb.) Gürke
• Mammillaria haseloffii Ehrenb.
• Mammillaria spinosissima var. hepatica (Ehrenb.) Labour.
• Mammillaria hepatica Ehrenb.
• Mammillaria seegeri var. gracilispina Salm-Dyck
• Mammillaria spinosissima var. herrmannii (Ehrenb.) Gürke
• Mammillaria herrmannii Ehrenb.
• Mammillaria spinosissima var. isabellina (Ehrenb.) Gürke
• Cactus isabellinus (Ehrenb.) Kuntze
• Mammillaria isabellina Ehrenb.
• Mammillaria spinosissima f. isabellina (Ehrenb.) Schelle
• Mammillaria spinosissima var. linkeana (Ehrenb.) Gürke
• Cactus linkeanus Kuntze
• Mammillaria linkeana Ehrenb.
• Mammillaria spinosissima var. mirabilis (Ehrenb.) Gürke
• Cactus mirabilis Kuntze
• Mammillaria mirabilis Ehrenb.
• Mammillaria seegeri var. mirabilis (Ehrenb.) Labour.
• Mammillaria spinosissima f. monstruosa hort.
• Mammillaria spinosissima var. polyacantha (Ehrenb.)
• Mammillaria polyacantha Ehrenb.
• Mammillaria spinosissima var. pretiosa (Ehrenb.) Scheele
• Cactus pretiosus (Ehrenb.) Kuntze
• Mammillaria pretiosa Ehrenb.
• Mammillaria spinosissima var. pruinosa (Ehrenb.) Gürke
• Mammillaria pruinosa Ehrenb.
• Mammillaria seegeri var. pruinosa (Ehrenb.) Salm-Dyck
• Mammillaria spinosissima var. pulcherrima (Ehrenb.) Gürke
• Cactus pulcherrimus (Ehrenb.) Kuntze
• Mammillaria pulcherrima Ehrenb.
• Mammillaria spinosissima f. rubens (Salm-Dyck) Gürke
• Mammillaria spinosissima rubens Salm-Dyck
• Mammillaria spinosissima f. rubrispina cristata hort.
• Mammillaria spinosissima f. rubrispina hort.
• Mammillaria spinosissima var. sanguinea (F.Haage) F.Haage in L.H.Bailey ex Brandegee
• Mammillaria sanguinea F.Haage ex Regel
• Mammillaria spinosissima var. seegeri (Ehrenb.) Gürke
• Mammillaria seegerii Ehrenb.
• Mammillaria spinosissima f. tepoztlanensis Bravo
• Mammillaria spinosissima f. typica Gürke
• Mammillaria spinosissima var. vulpina (Ehrenb.) Gürke
• Cactus vulpinus var. Kuntze (Ehrenb.) Kuntze
• Mammillaria vulpina var. Ehrenb. Ehrenb.
• Mammillaria virginis Fittkau & Kladiwa in Krainz

• Mammillaria spinosissima subs. tepoxtlana D.R.Hunt
• Mammillaria crassior Repp.
• Mammillaria spinosissima var. auricoma (A.Dietr.) Gürke
• Cactus auricomus (A.Dietr.) Kuntze
• Mammillaria auricoma A.Dietr.
• Mammillaria spinosissima f. auricoma (A.Dietr.) Schelle

• Mammillaria spinosissima cv. Un Pico
• Mammillaria spinosissima cv. Un Pico cristata
• Mammillaria spinosissima cv. Un Pico Monstruosa

Description: Mammillaria spinosissimaSN|13792]]SN|13783]] ssp pilcayensis is distinguishing subspecies that has whiter, shorter and very dense spination, and the stems can grow up to 50 cm long. Central and radial spines are all similar, about 30-34, pale glassy yellow and 5-6 mm long. It might have some latex and bristles in the axils. The flowers are purple-pink. It is very similar to Mammillaria pitcayensisSN|13783]]SN|13792]]var. chrysodactyla.
Derivation of specific name: "pilcayensis" For the occurrence in the Barranca de Pilcaya, Guerrero, Mexico.
Habit: The plants are solitary or sparsely branched from the base, with stems almost horizontal and threatening to hang down, although they continue to flower prolifically.
Stems: Cylindrical, dark blue-green, 15-50 cm in length, 4(-5) cm in diameter and may need something to lean on. May have some latex.
Tubercles: Ovate-conical to cylindrical-conical, 5 mm long and 2-3 mm in diameter, four-sided basally, soft, with milky juice. Axil woolly and with 8-10 slender bristles. Tubercule arrangement 13-21.
Central spine: About 14 (-17), thin, needle-like, bristly, very thin and flexible, translucent greyish white or yellow, sometimes brown tipped, 5-6 mm long.
Radial spine: 17, similar to the centrals.
Flower: Purplish, about 2 cm long and in diameter.
Fruit: Dull purplish red or greenish.
Seed: Brown.

Bibliography: Major references and further lectures
1) Jorge Meyrán García, Ignacio Piña Luján “Cactáceas y otras suculentas del Estado de México” Gobierno del Estado de México, 01 January 1986
2) Edward Anderson “The Cactus family” Timber Press, Incorporated, 2001
3) 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
4) David R Hunt; Nigel P Taylor; Graham Charles; International Cactaceae Systematics Group. "The New Cactus Lexicon" dh books, 2006
5) John Pilbeam “Mammillaria: the cactus file handbook” Cirio Publishing Services Ltd December/30,/1999
6) The Journal of the Mammillaria Society, Mammillaria Society, 1980
7) Urs Eggli, Leonard E. Newton “Etymological Dictionary of Succulent Plant Names” Springer Science & Business Media, 11 March 2004

Cultivation and Propagation: Mammillaria spinosissima subs. pilcayensisSN|11357]]SN|11357]] 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.