Button Cactus, Mulatto, Tapone

The differences between the subspecies are:
--ssp. micromeris; Has a neater, smaller, tighter look; the tops are very depressed....Read Morer /> --ssp. greggii; Larger up to 2 inches across; Has a rough, bristly look, pink flowers.
--ssp. pachyrhiza; the roots are tuberous, only partially covered with orange-tan to white spines, Pinkish-white flowers.
--ssp. polycephala; forms clusters, Each stem about 1 inch across, All 21-27 spines (per areole) are about the same color (white) and length. Pinkish-white flowers
--ssp. unguispina; forms clumps, has long black tipped central spines, the pink flowers are larger than the others.

Other valid synonyms are Cephalomamillaria greggii & Epithelantha micromeris var. greggii