Mammillaria tetrancistra

Mammillaria tetrancistra is one of only two Mammillaria growing in California. This is a Mohave desert plant with large areal. It also occurs in Arizona, Nevada and probably Utah. In California it is known to grow on the hilltops near Death Valley, the most hostile North American desert. Of cause the hill tops are cooler in the summer and they also getting a bit more of winter moisture, but it is also colder in the winter up there.
Mammillaria tetrancistra looks pretty much like any other Mammillaria with hooked centrals, with larger pink flowers. It is neat and desirable plant, but rarely seen in cultivation. It is also considered the most difficult Mammillaria to grow. The plant is adapted to Mojave desert rain pattern with no precipitation during the hot summer months. That makes cultural requirements same as for most of the Sclerocactus species, to no surprise - the are from same general area and climate. Plants are moderately frost hardy an are fine with winter watering, provided the grow media is proper.
The picture is taken in Joshua Tree National Park, in California, at the last week of April. I was looking for the plants at the small area, may me 100ft by 15 ft, and I knew that there are at least a dozen plants there. It still took me about half an hour to find the first plant, and if not for the red fruit I'd have no doubt missed them.