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 Isla Margarita and Isla Magdalena off the west coast of Baja California Sur, where it occurs abundantly in rocky terrain. Known for forming large clumps with relatively long creeping stems, this species is attractive for its flowers and stems. These plants are seedlings in 4-inch pots.
