Gymnocalycium ragonesii

This cactus is a small and very slowly growing cactus. It has a dark brown epidermis, and it also has short and pale spines that are flattened against its body. The flowers usually begin to bloom in the late spring and open for about 12 days; they are white and pinkish with a yellow middle.

Recommended temperature zone: USDA: 9b-11
Minimum avg. temperature: 50°F (10°C)
Heat tolerance: Light shade in Phoenix
Sun exposure: Light shade to full sun
Origin: Argentina (Catamarca, Cordoba) at low elevation
Watering needs: Summer grower, water regularly in summer, keep rather dry in winter
Propagation: Seeds

Some of the information in this description has been found at desert-tropicals.com, llifle.com and cactus-art.biz