From the Latin mamma, the breast, or mamilla, nipple, in reference to the teatlike tubercles of many species (Cactaceae). A large genus of greenhouse succulent perennials, suitable for window culture. Most species are from the southern parts of North America and Mexico and can be recognised by the numerous tubercles covering them; there are no ribs as on many globular cacti. They are mostly dwarf plants forming large groups (caespitose), but there are a few taller ones. Mammiliarias have areoles between the tubercles from whicharise; they also have areoles on the tops of the tubercles from which the species arise. Offsets can form from either type of areole. The flowers are produced in rings near the growing centre between the tubercles (axils). No more flowers will appear at the areole where it has already borne a flower and so fresh growth must be encouraged each year.
There are over 300 species and many varieties — the following is a mere selection: M. albicans, densely covered with white spines, red flowers. M. bocasana, grouping, with silky white hairs and red hooks. flowers pink. M. camptotricha, pale green body with golden twisting spines, white flowers. M. decipiens, grouping. large tubercles with red spines, flowers pink or white. M. elongata, finger-like stems, many varieties, flowers white. M. fraileana, tall-growing with strong hooks, large pink flowers. M. gracilis, small type with offsets which fall readily. flowers yellowish. M. hahniana, very attractive, with long white hairs, red flowers, M. innae, small-growing, white-spined species, red flowers. M. jaliscana. globular, freely offsetting with large pinkish-red flowers. M. karwinshiana, open type with strong spines, cream coloured inner petals. M. longiflora, very long thin tubercles, many thin spines, long tubed pink flowers, central spine hooked. M. magnimamma, open type with many varieties, strong spines, flowers cream. M. nunezii, columnar growing, many fine spines, red flowers. M. orcuttii, dense white wool at top with dark spines, flowers pale red with darker mid-rib. M. plumosa, handsome species with feather-like spines, flowers pink, December.
M. quevedoi, globular with white spines and wool at top. M. rhodantha, columnar growth with brassy-spines, flowers pink. M. spinosissima, tall cylindrical type with many spines, yellow, brown, or red, flowers purplish. M. tetracantha, open type, with stiff spines, flowers pink. M. uncinata, open type with a hooked spine at each areole, flowers pink. M. vaupelii, covered with yellow and brown short spines, attractive. M. wildii, common species with yellow spines and hooks, flowers white.
M. xanthina, rare species with strong hooks. M. yaquensis, small type making groups with fierce hooks. M. zeilman-niana, the most free-flowering species, with soft tubercles and cerise flowers.
Grow mammillarias in an average potting compost with 1/6 part of sharp sand, grit and broken brick added. Repot in March or April, once every year or two; do not use a large pot. Water well from March to October, as often as thedries out, but do not give any water from October to February. The temperature in winter should be 40 °F (4°C) and in summer 65-85 °F (18-30°C). Some species, from Baja, California and the West Indies, require a higher winter temperature. Some open types need a little shade from strong sunshine.
Plants are easily raised from seed sown in pans of a good seed compost in February in a temperature of 70 °F (21°C). Keep the pans of seedlings at this temperature, moist and shaded. Offsets may also be rooted in a mixture of sharp sand and peat in equal parts. Some species may be increased by detaching and rooting tubercles.