Etymology - from the Greek a meaning without and charagma - groove - see description below
Two species from Coahuila and Nuevo Leon -Mexico make up the entirety of the Genus Acharagma. These plants have globose bodies less than 3 inches in diameter and no more than 3 inches high. They may be somewhat cylindrical in shape and typically grow as individuals, but may put off several offsets from the bottom. These plants have tubercles and flower from the top, which is similar to both Escobaria and Coryphantha, however, they do not have a groove from the areole to the axis. In fact, the name Acharagma means in Greek "no groove". [a (no) - charagma (groove)]. The flowers are white to red to yellow and the sepals at least have a darker vertical stripe. The spines are quite thick and can obscure much of the stem and are less than an inch in length. The fruits are smooth little pods that are green to purple colored.
Aside from Escobaria, some have considered these plants to possibly fit in Echinocactus, Gymnocactus, and Turbinicarpus, but as for now, most maintain that a separate genus is most fitting.