The World Flora Online

Plants mostly erect (rarely decumbent or prostrate), branched or unbranched, deep-seated in substrate or not. Roots diffuse or taproots (adventitious from offsets in M. thornberi and M. prolifera). Stems unsegmented, green to gray-green, sometimes purplish under stress, spheric to cylindric or turbinate, often flat-topped, 1-15(-25) × 1.8-12(-20) cm, firm or flaccid; tubercles distinct, not confluent into ribs, pyramidal, conic, or cylindric, 3-25 × 2-9 mm; areoles of 2 kinds: vegetative areoles (spine clusters) at tips of tubercles; reproductive areoles in axils of tubercles, woolly, bristly, or naked; areolar glands absent; cortex and pith usually not mucilaginous, instead containing latex (absent in M. grahamii). Spines [2-]5-80(-90) per areole, of every color that cactus spines can be, hairlike, bristlelike, or needlelike, glabrous or plumose, (0.5-)2-25(-31) × 0.01-0.6 mm; radial spines (6-)10-80 per areole, straight to curved or crinkly bristles, (0.6-)3-25 mm; central spines 0-several (indefinitely numerous and intergrading with radial spines in M. lasiacantha), straight, curved, or hooked, terete. Flowers diurnal, in ring distant from stem apex (or nearly apical at anthesis forming a ring around new growth, subsequent apical growth displacing fruits even farther away from apex), in axils of tubercles, unconnected to spine clusters, funnelform, campanulate, or rotate, 0.9-4(-5.2) × 0.6-3.5(-7.5) cm; outer tepal margins entire or fringed; inner tepals yellow, white, rose-pink, magenta, or maroon, 4-30 × 1.5-8.5 mm; ovary lacking scales and spines; stigma lobes cream, yellow, red, pink, or brownish green, 0.3-8 mm. Fruits indehiscent, usually pink, bright red, or greenish, green and barrel-shaped when seeds mature, sometimes becoming colored and clavate or cylindric to ovoid, 5-30(-40) × (2-)4-9(-26) mm, usually juicy; scales and spines absent (or rudimentary); floral remnant persistent to quickly deciduous. Seeds black, brown, reddish, or yellowish (with tan, corky strophioles in M. tetrancistra), 0.8-1.5 × 0.6-1.4 mm, usually pitted or raised-reticulate (with additional wrinkling in M. tetrancistra) [impressed-reticulate M. candida of Mexico], often shiny; testa cells flat to concave, walls straight to sinuate. x = 11.

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MAMMILLARIA Haw.

Tallos cortos, solitarios o agrupados, erectos o decumbentes, globosos a cortamente cilíndricos, tuberculados, látex presente en algunas especies; espinas pocas a numerosas, frecuentemente las radiales y centrales dimorfas; aréolas floreciendo en las axilas de los tubérculos. Flores generalmente pequeñas, regulares, campanuladas; tubo receptacular corto, desnudo; partes del perianto patentes. Frutos carnosos, secándose después de madurar, indehiscentes; semillas negras o cafés.

Un género con 250 especies distribuidas desde el suroeste de los Estados Unidos hasta Nicaragua, Colombia, Venezuela y las Antillas, más abundante en México; 2 especies se conocen en Nicaragua.

R. Craig. The Mammillaria Handbook. 1945.

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Plants spherical or nearly cylindrical. Spines on spirally arranged tubercles, the tubercles cylindrical and green, usually with white hairs or bristles in axils. Flowers small, solitary, borne axillary to the tubercles. Perianth yellow or white; stamens numerous, united into a tube; style not protruding, the stigmas filiform. Fruit club-shaped or pyriform, pink or red, smooth, with numerous minute brown or black seeds.

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A genus of about 150 species, ranging from southwestern United States to northern South America, including the West Indies.

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SELECTED REFERENCES

Craig, R. T. 1945. The Mammillaria Handbook....Pasadena. Hunt, D. R. 1987. A New Review of Mammillaria Names. Botley. [Reprinted from Bradleya 1-5, 1983-1987.] Pilbeam, J. 1981. Mammillaria: A Collector’s Guide. London. Reppenhagen, W. 1989. Die Gattung Mammillaria nach dem heutigen Stand meines Wissens, 1988. Frankenthal.

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