Small, densely clumping cactus forming flat-topped mounds. 0-2 straight, reddish brown central spines; 11-25(-50) thin white radial spines. Pale yellow or whitish flowers. From Hidalgo, Guanajuato and Querétaro in north-central Mexico. Stems break off easily and are easily rooted. An excellent container plant. Widely available, easy.

Two subspecies are recognized: Mammillaria (Mammillaria vetula subsp. vetula) (1-2 central spines, 25+ radials) and the much more common (in cultivation) Thimble Cactus (Mammillaria vetula subsp. gracilis) (often 0 central spines, 11-16 radials).

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