Origin and Habitat: Veracruz (near Azumbitla), on the border with puebla, at puerto del aire near Acultzingo, Mexico. (Northern America).
Type Locality: Grenzpas Puebla - Veracruz, Puerto del Aire.
Altitude range: Around 1850 metres above sea level. And also at Tecamayuca, Veracruz, Mexico at an altitude of 1400m (a.k.a. “ruber” form)
Habitat and ecology: Mammillaria erythraSN|20663]]SN|20663]] grows on lava rocks in a humus rich substrate.

• Mammillaria erythra Repp.

• Mammillaria mystax Mart.
• Cactus mystax (Mart.) Kuntze
• Neomammillaria mystax (Mart.) Britton & Rose
• Mammillaria atroflorens Backeb.
• Mammillaria casoi Bravo
• Mammillaria crispiseta R.T.Craig
• Mammillaria erythra Repp.
• Mammillaria erythra f. ruber Repp., n.n.
• Mammillaria ruber Repp.
• Mammillaria mixtecensis Bravo
• Mammillaria mystax var. huajuapensis (Bravo) Lizen
• Mammillaria huajuapensis Bravo

Description: Mammillaria erythra is a solitary, flattened globose, cactus, with long pyramidal, four-angled tubercles and short distinctive spines. It is at most a race of the variably spined Mammillaria mystaxSN|20654]]SN|20654]]. The key difference by which the two were separated, namely the reduced spination, the dull-green epidermis, the solitary growth and the body size, seems entirely spurious. The name Mammillaria erythraSN|20663]]SN|20663]] is not accepted by many botanists that treat it as synonym, but it still has a value for a collector because they identify plants with particular characters.
Remarks: Mammillaria erythraSN|20663]]SN|20663]] is considered by Werner Reppenhagen a connection between Mammillaria mystaxSN|20654]]SN|20654]] and Mammillaria sartori.
Stem: Solitary, flattened globose, sunken apex, 4-9 mm high and 7-30 cm in diameter, dull green, in habitat reddish. With latex.
Roots: Fibrous.
Tubercles: Pyramidal, firm, 4-angled, keeled, 15-18 mm long and 12-15 mm wide. Axil with short white wool and 3-10 short, glassy white with reddish brown tip, straight bristles.
Radial spine: None to 8, needle like, straight, smooth, whitish to brown, 2-6 mm long.
Central spine: 1 - 4, the uppermost the longest, needle like, straight or slightly curving, with thicker base, glassy brown with black tip, to 50 mm long.
Flower: Carmine, funnelform, 18 - 22 mm long and 10 - 12 mm in diameter, not flowering frequently.
Fruit: Dark carmine, club-shaped, 10 - 15 mm long and 3 - 5 mm wide, ripens 5 months after flowering.
Seed: Brown, flattened keeled, 1,2 mm long and 0,8 mm wide. Hilum subbasal.

Bibliography: Major references and further lectures:
1) David Hunt, Nigel Taylor “The New Cactus Lexicon” DH Books, 2006
2) John Pilbeam (1999) “Mammillaria The Cactus File Handbook” Nuffield Press.
3) Reppenhagen “Die gattung Mammillaria nach dem heutigen stand meines wissens 1987” Herausgeber AfM, 1987: 180 - 182 , 199 and 222.

Cultivation and Propagation: Requires excellent drainage provided by porous cactus soil. We suggest repotting every 2-3 years. Prefers bright light and ample airflow. Outside full sun or afternoon shade, inside it needs bright light, and some direct sun. Water the soil abundantly when it is dry to the touch. Allow soil to drain thoroughly before watering again. Do not water much in the winter (Rot prone). Protect from frost. But it's hardy to -5°C if kept dry. During the beautiful 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.
Propagation: Direct sow after last frost as it usually don't braches.