A Group of Cacti

Genus Mammillaria

English names: pincushion cactus, mammillaria, nipple cactus

Small, attractive, diverse, and generally easy to cultivate, mammillarias enjoy enormous popularity with collectors.

Description of Genus

Even after duplicate names are sorted out, Mammillaria is the largest of several genera of diminutive cacti with about 175 species worldwide. The Sonoran Desert species are less than 6 inches (15 cm) tall, with closely-spaced areoles bearing many spines that obscure the body of the plant. The areoles are at the tips of long tubercles that are arranged in 2 spirals (one clockwise, the other counterclockwise). These tuberculate stems contrast with the ribbed stems of the genus Echinocereus. In addition, many mammillarias have hooked central spines, whereas no hedgehog does. Plants range from single stems to large clusters, depending on species. Flowers, usually less than an inch (25 mm) in diameter and either pink or white, are produced in a ring near the tip of the stem.

– from Arizona-Sonora Museum