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FNA | Family List | FNA Vol. 4 | Cactaceae | Mammillaria

12. Mammillaria heyderi Muehlenpfordt, Allg. Gartenzeitung. 16: 20. 1848 (as Mamillaria).

Little nipple cactus

Plants unbranched, protruding relatively little above soil. Roots obconic taproots; secondary roots diffuse. Stems top-shaped, flat-topped (aerial part sometimes hemispheric in old age or in dense subtropical vegetation), protruding above ground 0-2 × (4-)7.5-15 cm, firm; tubercles 9-15(-20) × 3-7 mm; axils with short wool, bristles absent; cortex and pith not mucilaginous; latex abundant in healthy tissue throughout cortex of stem, tubercles, and sometimes flower receptacle, sticky, white. Spines (8-)10-18(-27) per areole, usually brownish, darker at tip, glabrous; radial spines (8-)10-22(-26) per areole, white to white-and-brown or brown , needlelike, 6-15(-16) mm, stiff, abaxial spines longest; central spines (0-)1(-4) per areole, porrect or ascending, not hooked, (0.5-)2-8 × 0.15-0.45 mm; subcentral spines 0. Flowers 1.9-3.8 × 1.5-3 cm; outermost tepal margins entire; inner tepals white, greenish or cream to pale pink, with tan, pink, greenish, or brownish midstripes, 11-19 × 2-2.5 mm; stigma lobes externally green, internally green or red (or pink), 2.5-3 mm. Fruits brilliant red: scarlet, carmine, or crimson, obovoid to clavate, 10-35(-40) × 5-8 mm, juicy only in fruit walls; floral remnant weakly persistent. Seeds reddish brown, sometimes yellowish when fresh, 1-1.2 mm, deeply pitted; testa thin, relatively flexible; anticlinal cell walls sinuate, interstices narrower than pit diameters; pits cavernous or deeply concave. 2n = 22.

Varieties 2 (2 in the flora): sw United States, n Mexico.

Green fruits of Mammillaria heyderi with fully mature, viable seeds precede the ripe (elongate) fruits by six months to a year.

1 Central spines 0.15-0.35 mm diam.; radial spines (7-)13-17(-26) per areole, abaxial radial spines 6-11(-16) mm; e of El Paso, Texas, New Mexico, Oklahoma.   12a var. heyderi
+ Central spines 0.35-0.45 mm diam.; radial spines 10-14 per areole, abaxial radial spines 9-15 mm; El Paso, Texas, w to Arizona.....   12b var. bullingtoniana<


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