Gymnocalycium marquezii

Gymnocalycium marquezii is a solitary or slowly clustering cactus, with peculiar spine clusters characteristically bent backward in a distinctive fashion. Gymnocalycium are very gratifying plants, their culture is easy and their flowering is abundant if we give them a well drained relatively rich substrate. Coloring of pale green, to olive green that can tinge of orangish purple in full sun. The plant tolerates extremely bright situations but enjoys filtered sunlight or afternoon shade, inside it needs bright light, and some direct sun. Tends to bronze in strong light, which encourages flowering and heavy spine production, but is likely to suffer from sun scorch or stunted growth if over exposed to direct sunlight during the hottest part of the day in summer. Originated in Bolivia.

Flowers: white with carmine/pink purplish throat

Spines: Strong, very stiff, bent backward, initially blackish with a brown base then becoming grey-pinkish to whitish brown with black point. 

Growth: It is a relatively rapidly growing and easily flowering species.
Watering: Needs moderate to copious waterings in summer, but do not overwater (Rot prone), keep dry in winter

Hardiness: Reputedly resistant to frost if kept on the dry side prior to. Hardy to (10 F/-12 C)
Sun needs: tolerates extremely bright situations but enjoys filtered sunlight or afternoon shade, inside it needs bright light, and some direct sun.