Mammillaria Cactus

There are two native species of Mammillaria cactus in our region - dioica and tetrancistra. Both are quite small plants, usually no more than 6" tall. The former is far more common, found from the immediate coast to the Anza-Borrego Desert. It has white or cream-colored flowers with a pink stripe on the outside of the tepals. Flowers typically appear in winter and spring in response to winter rain. Tetrancistra is found only in the desert. It has pink flowers that appear in late summer or fall in response to monsoonal rain. They also differ in some other ways, such as the number and arrangement of the spines.

I have a couple of dioica in my Encinitas garden, and one of them in particular blooms like crazy. I was doing some gardening today and noticed that it has flowers already. This is probably the result of me watering the garden one day in early October when it was cloudy and cool. I did not expect this one to flower so prolifically because it is in a very shady spot.

It looks like there are 4 fully developed flowers and perhaps 16 buds. Here's a closeup of one flower.

It looks like it has both male and female parts. Other flowers on the same plant can be all female.

I'm going to try to keep an eye on it to see how long the individual flowers last and how many times it can produce flowers.