The M. bombycina produces numerous heads (the little white clump to the right is another head forming) and each of those heads will have a ring of 1/2- inch, enduring pink flowers near the crown. At a recent Cactus and Succulent Society show, I saw a mature specimen in a 14-inch pot with at least 28 heads. Every head was in full bloom, and it was stunning.
This cactus comes from the high mountains of Western and Central Mexico, so it can take lower winter temperatures than many of the other Mammillaria species. It needs moderate summer water and light shade in Phoenix. I keep it dry in winter to prevent rot.
This Mammillaria species is supposedly popular with new collectors, but around the Phoenix area, it is hard to find except in cactus nurseries, and I've never seen it planted in a garden. If I could find a couple of larger ones, I'd like to try them under the canopy of a Palo Verde tree.