Oehmea

A Mexican cactus with globose to short cylindrical stems, a longer hooked spine and showy yellow-orange flowers. Previously known as Mammillaria beneckei. Oehmea nelsonii, the type species of the genus, is now one of its synonyms.

A branching cactus of limestone habitats in Puebla and Oaxaca, formerly Mammillaria sphacelata. Slender stems form groups, and purple or red flowers appear at regional sites from October to April. Two subspecies with different stem proportions and spine counts are accepted.

A cactus from Oaxaca with branched, slender stems and one hooked central spine. The flowers are carmine, with paler tepal margins. Described as Mammillaria tonalensis, it has had the accepted name Oehmea tonalensis since 2022.