Ranging across a slice of Mexico from Chihuahua to Jalisco, Mammillaria senilis is a beautiful white clumping cactus that can get 6 inches high and 4 inches around. It's looks are deceiving, though the radial spines are soft the centrals are long and hooked. Get to close to you and it grabs you like velcro. Not quite a pettable cacti. In late winter and spring breathtaking deep scarlet flowers are produced.
     I tried growing one of these in the ground but the winter rains rotted it. So I guess I'll stick to pot culture with this plant.