This genus is endemic to arid South American deserts, from southern Peru to central Chile, up to Argentina. Many species live at very high altitudes where they survive significant changes in temperature and high concentration of UV rays.
Eriosyce is one of the most species-rich genera and includes Neochilenia, Neoporteria, Thelocephala, Islaya and Pyrrhocactus, among others… a maze of species that contribute to the current taxonomic instability of the genus. Neochilenia has short to no spines and funnel shaped flowers, while species in the Neoporteria group have denser, longer spines in general than Neochilenia and more colourful flowers. Not difficult to grow, if we consider their native habitat. Eriosyce laui is the smallest cactus in the genus and is listed as critically endangered, while Eriosyce aurata, with spines and a size similar to Echinocactus grusoni, is the largest one.