Gymnocalycium is a genus of about 70 South American species. Their main area of distribution is Argentine, part of Uruguay, Paraguay, southern Bolivia, and part of Brasil. Most species are globose, rather small varying from 1.5 to 6 inches in size (4 cm to 15 cm).
They are popular for their easy flowering habits, although the flowers are generally brightly colored. They are also popular for their ease to care. The genus name "Gymnocalycium" comes from the Greek for "naked calyx" referring to the flower buds bearing no hair or spines.