Coryphantha macromeris

Coryphantha macromeris DJF1353 El Paso, TX. 
It is a hardy cactus with long, dark spines which branches  profusely, ultimately forming low mats or hemispheric mounds to 100 cm diameter.

Description: Plants profusely branched with long projecting spines, ultimately forming low mats or hemispheric mounds to 100 cm diameter
Stem: Noticeably tuberculate, hemispheric to short cylindrical, sometimes obscured by profusion of immature branches, 4-12 cm; tubercles unusually large 15-25 mm and grooved only on the upper half, flaccid or flabby; areolar glands seasonally conspicuous;
Root: It has deep succulent taproot often massive and large.
Spines: Weakly appressed or projecting, slightly curved, often flexible. Radial 9-15   per areole, e, grey, tan, or brown, 15-25 mm long; subcentral spines 2-3 in adaxial part of areole; central spines 3-8 per areole, pale grey to black, abaxial central spine porrect or descending,
Flowers: apical or nearly so at mid-level of tubercle, outer tepals heavily fringed; flower bright rose-pink or magenta, often with darker midstripes and paler margins
Fruits: Dark green, ovoid to obpyriform or ellipsoid.

Note (1): C. macromeris pass several stages of development in which their appearance changes and stunted or immature plants are variable, often have only 5-7 radial spines and lacking central spines. It has strongly mucilaginous cortex even small slices of living tubercle tissue are visibly and tangibly slimy.

Notes (2): The showy flowers of C. macromerisare virtually identical to those of Mammillaria wrightii and Escobaria vivipara; in the absence of vegetative material, flowers may be unidentifiable.

Cultivation:  Popular with collectors and easy to grow, Hardy to -10° C. Water sparingly, needs good drainage. Keep drier in winter, Full sun to partial shade,
 

Scientific name: Coryphantha macromeris (Engelmann) Lemaire, Cactées. 35. 1868

Synonyms:

• Mammillaria macromeris Engelmann in F. A. Wislizenus, Mem. Tour N. Mexico, 97. 1848;
• Coryphantha macromeris var. runyonii (Britton & Rose) L. D. Benson;
• Coryphantha macromeris subsp. runyonii (Britton & Rose) N. P. Taylor;
• Coryphantha pirtlei Werdermann;
• Coryphantha runyonii Britton & Rose;
• Lepidocoryphantha macromeris (Engelmann) Backeberg

Origin: New Mexico, Texas ; Mexico (Chihuahua, Coahuila, Durango, Zacatecas).

Habitat: grows nearly in all substrates including nearly pure gypsum, gravelly soils, usually sandy alluvium or clay, rarely crevices or steep slopes; 30-1700(-2000) m.
 

 
The blooms are large bright lavender to magenta over long periods from March to early September.