Although some consider this to be part of the genus Mammillaria, we keep it separate, in large part because of the large, red tubular flowers with irregular lips. This species is endemic to Baja California, where it occurs mostly south in Baja California Sur. Known for forming large clumps with relatively short stems, this species is both attractive and highly resistant to frost. Our plants were undamaged at 15F. These plants are seedlings in 6-inch pots.