The Santa-Rita Prickly Pear always has some purple coloring on the pads, which is pronounced in cold weather. The color gradually lightens as the weather warms. O. santa-rita blooms in May, and the pale yellow flowers beautifully complement the purple pads.
The central spines on M. duoformis are dark brown and hooked. M. duoformis has several forms, and the tenango de valle is one of them. The one constant is that all M. duoformis forms have dark red flowers. However, some sources claim that the tenango de valle form has white flowers, and that was what I expected with this cactus. Now that it has bloomed for the first time, I don't know what to think. It's definitely an M. duoformis, so I guess that's good enough!
Many species of Mammillaria need light shade in Phoenix, so I have them planted under the dappled shade of the Palo Verde trees. It provides the perfect environment for protection in brutal summers, and offers some protection from frost. The downside is that most Mammillaria flower in late April/early May, just when the Palo Verde is in full bloom. The result is cacti covered with dried Palo Verde flowers, which are impossible to remove without using a blower. Even then, remnants remain for a couple of months. I tried to clean this one off for a decent photo, to no avail. The hooked central spines of the M. magnifica exacerbate the problem.
The insignificant flowers of the M. marksiana (Cabeza de Viejo) take a back seat to the spirally arranged prominent tubercles that form a clear wheel-like pattern that seems to be moving when you stare at it. The wooly axils help guide the eye to its spiral shape. This is a great example of the symmetry of cacti.