From Mammillaria, and the Greek opsis, appearance, in reference to their resemblance to the mammillarias (Cactaceae). A genus of a few species of greenhouse succulent plants, with white spines. They make handsome plants not commonly found in collections. The white spines, many of which are hooked, form a dense covering.
M. diguetii has stronger spines and smallerthan the following species, Mexico. M. senilis, a very attractive plant, globular to cylindrical, with many white spines and hooks, reddish flowers 2 inches across, Mexico. Must have plenty of light and air.
Use compost with few added nutrients with s part added of coarse sandy grit and broken brick. Pot every three years in March, and give the plants a very sunny place in the greenhouse. Do not water between October and March, but between March and September water well when thein the pot has dried out. The winter temperature should not be less than 40°F (4°C).
Propagate from seed sown in pans of regular seed compost, where a temperature of 70°F (21°C) can be maintained. Cover the seed lightly, keep it moist and shaded until germination, then give light but not direct sun. Offsets can be removed and rooted in coarse sand.