All the information and photos in cactus art files are now available also in the new the Enciclopedia of Cacti. We hope you find this new site informative and useful.

 M. geminispina ( forma 'nobilis' ) has long flexible spines that cover the new growth,
flowers are carmine in late spring and sometime in autumn too.  
 

Description: It is a highly variable densely spined species. Some cluster aggressively and form 30 to 90cm large clumps that appear white, while other seem to stay more solitary.
Stem:  Short cylindrical, light green whit latex, up to 18 cm high and 8 cm in diameter.
Tubercles: Rounded with latex.
Axil: With white wool and 10 - 20 long white bristles.
Spines: Spines are variable too, some plants have very short while others have long spines.
Central spines: 2 (to 6) pure white or white with dark tip that protrude far out from the rest, straight or slightly curved, 0,5 to 4 cm long (or more).
Radial spines: 16 to 20 chalky white, interlacing up to 7 mm long.
Flower: Campanulate, pinkish to carmine red, with darker midveins, to 20 mm long and in diameter usually in a ring in the growth of the previous year but sometime more randomly over the body. If grown from seed, M. geminispina can take seven to eight years before flowering.
Fruit: red
Seed: Brown.

Some clones cluster aggressively and can form 50-90 cm wide white, gorgeous mounds as they matures.

Cultivation:   It is a fairly easy plant to grow, don't requires any special treatment, but need as much light as possible without burning the plant to encourage the heaviest spine formation, if kept too dark it may become overly lush and greener and could be prone to rotting due to over watering.
During the summer it is best to keep the plants outside where the temperature can rise to over 30 C with no harm to the plant. Furnish good drainage and use a an open and free draining mineral compost that allows therefore roots to breath. They like only a short winter's rest and should be kept almost completely dry during the winter months, If the soil is allowed to be dry for too long root loss could follow but equally the same result would occur if the plants are both wet and cold. From March onwards the plant will begin to grow and watering should be increased gradually until late May when the plant should be in full growth.
Water regularly during the summer so long as the plant pot is allowed to drain and not sit in a tray of water. During hot weather you may need to water the plants more frequently so long as the plant is actively growing. From late September watering should be reduced to force the plant to go in to a state of semi dormancy, by October you should be back in to the winter watering regime.
Feeding may not be necessary at all if the compost is fresh then, feed in summer only if the plant hasn't been repotted recently. Do not feed the plants from September onwards as this can cause lush growth which can be fatal during the darker cold months. Grown specimens resist to -4°C for a short time, but it is best to keep above 0° C to avoid ugly spots on the plant epidermis.

Propagation: Seeds or by  stem cuttings from adult plants.
 

Photo of conspecific taxa, varieties, forms and cultivars of Mammillaria geminispina.

• Mammillaria geminispina
• Mammillaria geminispina var. nobilis forma cristata

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Scientific name:  Mammillaria geminispina Haworth 1824
First description published in: Phil. Mag. 63:42 (1824)

Origin:  Hidalgo, Queretaro and San Luis Potosi, Mexico. Altitude 1.000 - 1.850 m.

Conservation status: Listed in CITES appendix 2.

Common English Names include: White cactus, twin spined cactus, whitey.

Synonyms:

• Mammillaria geminispina Hawort 1824
  = Cactus geminispinus
  = Neomammillaria geminispina
• Mammillaria elegans  A.P. De candolle 1828
  = Cactus elegans
  = Neomammillaria elegans
• Neomammillaria neo-elegans
  Mammillaria leucocentra Berg 1840
  Mammillaria geminispina subsp. leucocentra (Berg) D.R. Hunt 1997
• Mammillaria albata Reppenhagen 1987

Latex from a cross-sectioned plant.

Mammillaria elegans A.P. de Candolle 1828. is a 'nomen confusum' also applied to Mammillaria haageana ssp elegans   and referes bolth to M. geminispina with latex in the stem (Subgenus Mammillaria section Hydrochylus series supertextae ) and to M. haageana, without latex in the stem ( Subgenus Mammillaria, section Galactophylous, series Leucocephale )

 M. geminispina 'nobilis'
This Mammillaria gets only better looking with age. It will continue to put on more and more heads, as well as more white cotton topping.
The heads form mounds that seem stacked on top of each other.

M. geminispina is a very variable species and some of the different growing forms has been for a long time considered separate and distinguished variety, for example:

• M. geminispina var. geminispina (form with 2 central, white with darker tipped spines)
• M. geminispina var brevispina (form with 2 short darker tipped central spines)
• M. geminispina var leucocentra (form with 5-6 pure white central spines)
• M. geminispina var nivea (form with pure white spines)
• M. geminispina var nobilis (form with long spines)

All the information and photos in cactus art files are now available also in the new the Enciclopedia of Cacti. We hope you find this new site informative and useful.