This is a single stemmed cactus with neat pyramid-shape tubercles and with age can offset to form loose clumps. It produces a profusion of rose colored flowers in a ring around the crown of the plant. Tiny fruits embedded between the tubercles follow the flowers, containing the seeds. Spines are of variable shape and length. This small Mammillaria will reach about 6” tall. Sometimes the spines at the apex of the plant, with age, can grow long and wirey.

Because of its size, this plant is best kept in a container, and in afternoon shade, or filtered bright light all day long, like under the edge of a mesquite tree. Most Mammillaria species appreciate more moisture in the hot season (so long as the soil mixture is very well-draining) and kept dry in the winter when plants are dormant. Plants are hardy to mid to lower 20s°F if not too wet.

The genus name Mammillaria refers to the Latin mammilla, "nipple", referring to the tubercles that are among the distinctive features of the genus. The specific epithet, mystax, is Latin meaning "mustache" and probably refers to the long twisted spines at the apex, especially as found on some wild specimens.

This species is native to Mexico, where it grows in highland regions in Guerrero, Oaxaca, and Puebla at elevations of 3,000 to 8,500 feet in elevation.

Mammillaria mystax on iNaturalist