Mammillaria coahuilense ssp. coahuilense

Mammillaria coahuilense SB699 Hipolito, Coahuila, Mexico.
A mature specimen (nine years old )
The imposing tap root drives the plant out of the pot substrate.

Description: Small geophyte cactus, with a heavy tap root that may exceed the size of the plant above soil level. Stems solitary flattened globose, blue-green, up to 5 cm high and alsoin diameter.
Spines: About 12-16, thin, bristle-like radial spines, slightly pubescent with darker tips, up to 6 mm long. Central spine: not present or 1, straight, needle-like, darker, up to 6 mm long.
Flower: White with pinkish midveins, very early in the season, February/March.
Fruit: Red clavate.

Cultivation: This species has few special demands. Whatever view one adopts, it is worth a place in every Mammillaria collection. The only problem is that it is very slow growing,  a plant for patient growers.
Like all thick-rooted species, it requires careful  watering (rot sensitive), and patience to match its slow growth. During the winter rest, the plant may pull near the surface of the potting mix.

Propagation: Direct sow after last frost. (it usually doesn't  produces offsets).
 

Photo of conspecific taxa, varieties, forms and cultivars of M. coahuilense.

• M. coahuilense
• M. coahuilensis subsp. albiarmata

Conservation status: Listed in CITES appendix 2.

Habitat: This plant is a mud crack dweller, growing almost sunken in cracks in the dry lake at the Laguna de Viesca. Altitude 1.000 to 1.230 m
 

Synonym:

• Porfiria coahuilensis Boed. 1926
• Mammillaria coahuilensis subsp. coahuilensis
• Mammillaria heyderi ssp. coahuilensis (Boed.) J.M. Luthy 1995
• Mammillaria schwartzii (Fric) Backeb. (Nom inval.) 1966
• Porfiria schwartzii Fric 1926

It is a rare and very slow  growing dwarf tuberous species, with a heavy tap root that may exceed the size of the plant above soil level.

A blooming plant from Vera Gheno collection