For over a month, I’ve researched my various reference books, looking for the identity of this cactus. When I bought it, it didn’t have a nametag, and all my efforts to find its genus and species were fruitless. Then today, while attending our local Cactus and Succulent Society meeting, I saw another cactus just like mine, in my sister’s hand. She had just purchased it, and it had a nametag!
It is called Ortegocactus macdougallii, and it is a close relative of the Mammillaria genus. It grows in limestone rock crevices in its native Mexico. O. macdougallii isn’t the easiest cactus to grow. It is prone to root rot, and it needs an average minimum temperature of 60º F. Had I known all that, I probably would have passed it up. I don’t need any more finicky specimens!
I do think the gray-green epidermis is striking, especially with the black spines. Sometimes the cactus gets a reddish orange discoloration on the skin, which is normal and not a sign of pests or problems. You can see a small area of this discoloration in the photo. This cactus will remain small and will produce relatively large lemon-yellow flowers in spring. It clumps when it is mature. This one has already produced two new stems.
Soil recommendations for this cactus are complicated, but the one I purchased is in plain old cactus soil mix and it seems to be doing fine, so I’m not going to change a thing. Now that my sister has one too, we can see who can keep hers alive longer!