Gymnocalycium monvillei

This Gymnocalycium monvillei is a globular, dark-green, grey-green to green cactus that can grow up 7 to 10" in diameter and up to 3" tall. The genus name "Gymnocalycium" comes from the Greek for "naked calyx" referring to the flower buds bearing no hair or spines. The flowers are some of the largest in this genus, often growing larger than the plant.

Recommended temperature zone: USDA: 9-11
Frost tolerance: Hardy to 18°F (-8°C)
Minimum avg. temperature: 50°F (10°C)
Sun exposure: Light shade
Origin: Argentina
Watering needs: Summer grower, water regularly in summer, keep rather dry in winter
Blooming habits: White flower, 3" in diameter (7 cm)

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