Mammillaria zeilmanniana aka Cactus

Mammillaria zeilmanniana is also called rose pincushion cactus. It belongs to the cactus family. Kew gives its home range as Guanajuato and Querétaro, Mexico. LLIFLE notes a small wild site near San Miguel de Allende. There, it grows on shaded volcanic cliffs in a canyon. Its roots reach into thin mats of moss and ferns. Trees and flowing water add moisture to this otherwise dry site. LLIFLE reports that the wild population is critically endangered. Illegal collecting drives its decline.

This small succulent forms clumps of round, glossy green stems. With age, stems may turn oval or form short cylinders. The RHS gives a garden height of 0.33 feet [0.1 metres]. Its listed spread is 0.33–1.64 feet [0.1–0.5 metres]. LLIFLE gives a stem height of up to 0.39 feet [0.12 metres]. White radial spines spread like fine hairs around each areole, a spine-bearing spot. Four central spines grow among them. These are reddish-brown. Three point straight out; the lowest has a hook. Young areoles bear wool. The axils, or spaces between the bumps, stay bare.

Pink-violet to purple flowers stand out against the pale spines. They reach about 0.07 feet [0.02 metres] long. Their stigmas, which receive pollen, have a yellow tint. Flowers can appear in any season, not at one set time. Fruits range from pale green with white tones to faint pink. The seeds are black. Growers raise this cactus for its flowers and small form. It suits pots and greenhouses, plus sheltered spots on patios. The RHS says it takes five to ten years to reach full size.

Under glass, give it strong but filtered light. Use an open cactus mix that drains fast. The RHS lists both sandy and loamy soils as suitable. The soil can be acidic, neutral or alkaline. Give modest amounts of water while it grows. Then keep it almost dry through winter. Keep the air dry and let it flow well. Use a pot deep enough for the main root, or taproot. LLIFLE suggests a new pot every two or three years. The RHS gives it an H2 hardiness rating. Protect it from freezing. LLIFLE reports that its frost tolerance varies. It advises winter warmth of 5–8°C.

Mealybugs may attack this cactus. The RHS lists few disease problems. LLIFLE warns that too much water can cause rot. It needs no pruning. Growers can raise new plants from seed or remove offsets. Sow seed in early spring at 19–24°C. Growers also raise plants for sale in the ornamental trade.