Coryphantha erecta

they're CORYPHANTHA ERECTA, endemic to three states here in north-central Mexico, but grown widely elsewhere because they are so handsome. I couldn't get to the plants to snatch a flower for certain identification, but they match pictures on the Internet. More

Coryphantha erecta at the Wallace's collection in Phoenix in April Recommended Temperature Zone: USDA: 9b-11 Minimum Avg. Temperature: 50F (10C) Heat Tolerance: Light shade in Phoenix in summer Sun Exposure: Full sun to partial shade Origin: Central Mexico (Queretaro, Hidalgo, Guanajuato) Growth Habits: Clumping cylindrical cactus; stems up to 12 inches tall (30 cm), 3.2 inches in diameter (8 cm); conical tubercles, 0.4 inch long (1 cm), 0. More