Mammillaria heyderi var. bullingtoniana Castetter, Pierce & Schwerin
Family: Cactaceae
not available
Stems 5-11 × 5-12(-15) cm; tubercles 11-25 × 4-8 mm. Spines usually 10-14 per areole; radial spines usually 10-14 per areole, abaxial radial spines 9-15 mm diam; central spines, when present, 0.35-0.45 mm diam. Flowers 2.2-3.3 × 1.7-3 cm. 2n = 22. Flowering Mar-May; fruiting Nov-May. Chihuahuan desert scrub, desert grasslands, lower edge of oak zone; 1200-2100 m; Ariz., N.Mex.; Mexico (Chihuahua). L. D. Benson´s (1982) concepts of Mammillaria gummifera varieties all included material of M. heyderi var. bullingtoniana. The stems, spines, and tubercles of var. bullingtoniana average about one-fourth larger than var. heyderi in all dimensions.