Gymnocalycium oenanthemum

Gymnocalycium oenanthemum is a species of flowering plant in the family Cactaceae, endemic to Argentina. A slightly flattened sphere growing to , it has 10-13 ribs, each containing a row of tubercles with radial spines. In summer it bears a wine-red or pink daisy-like flower. 
In cultivation in the UK and other temperate regions it cannot survive freezing, so at least in the winter months it must be kept indoors in a bright, cool environment with minimal watering. It has gained the Royal Horticultural Society’s Award of Garden Merit. 