PlantFiles: Mammillaria
Mammillaria karwinskiana

The differences between the subspecies are:
--ssp. karwinskiana; has medium yellow flowers with purpleish midviens; No central spines and 6 radial spines.
--ssp. collinsii; has white flowers with deeper pinkish midveins; One central spine and 7 radial spines.
--ssp. beiselii; has white flowers with red tinted midveins; One central spine and 5-8 radial spines.
--ssp. nejapensis; also has white flowers with red tinted midveins, but the spines are larger and white and has much more wool; No central spines and 3-5 radial spines per areole.

Other synonyms are: Mammillaria ebenacantha, Mammillaria conzattii, Mammillaria viridis var. praelii, Mammillaria pyrrhocephala var. confusa, Mammillaria jozef-bergeri, Mammillaria nagliana, Mammillaria pyrrhocephala, Mammillaria fischeri, Mammillaria tropica, Cactus karwinskianus, Cactus praelii, Neomammillaria neomystax, Neomammillaria confusa, Neomammillaria praelii, Neomammillaria karwinskiana

Not a very spiny Mammillaria so the 'nipples' (for which the genus is named after) are noticable. Develops some cream colored 'snowy' tomentum on top of plant. Branches dichotomously slowly and can get up to 5" in diameter. Doesn't like much, if any, winter water. From Oaxaca Mexico. This plant has so many synonyms I can't begin to list them all (found about 14 so far)