Mammillaria perbella

Mammillaria perbella is a small cactus from central Mexico. Its range runs from Guanajuato through Querétaro to Hidalgo. It belongs to the cactus family, Cactaceae. It grows in dry scrub on slopes of limestone. Plants nestle between rocks where soil has gathered. Sources place its habitat at elevations of 4,920–9,190 feet [1,500–2,800 metres]. It keeps its green stems year-round and lives for many years.

The stem starts round, then becomes more like a cylinder. Stems reach about 0.16–0.66 feet [0.05–0.20 metres] tall. Each measures about 0.16–0.26 feet [0.05–0.08 metres] across. The dull green body has a sunken, white-looking top. Short, dense spines cover much of its surface. Each group has about 20–30 white spines spreading outwards. The central spines are brown with darker tips. The stem base can turn corky with age. Older plants may split at the tip into two heads. Further splits can form a cluster; basal shoots occur less often.

Small flowers have a funnel shape and purplish-pink petals. A darker stripe runs along each petal's centre. Flowers measure roughly 0.03–0.04 feet [0.010–0.012 metres] across. The plant cannot set fruit with its own pollen. Its slender, club-shaped fruits turn a muted pinkish red. They ripen about seven months after the flowers appear. Small brown seeds lie within the fruit. People gather the fruit from wild plants and eat it raw.

This cactus grows very slowly, but LLIFLE describes cultivation as easy. Give it full sun to help keep its shape compact. Use a mineral growing mix that lets water drain well. LLIFLE advises against peat and other humus-rich potting ingredients. Water regularly, and provide heat during the growing season. Dry conditions help it cope with some cold. One source reports brief survival near 19°F [-7°C] in its native habitat. This does not establish a reliable garden hardiness zone. Seed provides a means of propagation. Removing a head from a divided plant may kill it.

Growers keep this species as an ornamental cactus. Useful Tropical Plants reports no known hazards or medicinal uses. It lists the species as Vulnerable, citing a 2017 assessment. Roads, rural development, trampling by livestock, and illegal collecting threaten wild plants.