Feather Cactus

Bearing edible, tomato-red fruits ('chilitos')

With about 170 species, Mammillaria form one of the larger cactus genera. The genus name, Mammillaria, comes from mammilla meaning ‘nipple’, in reference to the tubercles, the nipple-like protuberances, from which the spines emerge. This distinguishes them from the more recognisable cacti with ribs aligned with spines. The spherical-shaped body is light green, but usually hidden under the fluffy white hairs that cover the cactus. Each ‘nipple’ or tubercle supports about 40 downy spines of 3 - 7 cm in length.

The flowers of Mammillaria appear, not from the areoles, but just in the axils between the tubercles. A ring of stiff, cream-white tubular flowers reaching 1.5 cm in length protrude slightly from the hairs to be pollinated by bees. After flowering they produce edible, tomato-red fruit (chilitos), usually hidden beneath the hairs.

Ecology and habitat

Mammillaria plumosa only grows in northeast Mexico. It can be found between, and on top of, limestone rocks and in dry, scanty vegetation on slopes between 700 and 1400 m above sea level. Due to its colour it is barely noticeable between the rocks. Its hairy appearance gives the cactus a great advantage in its natural environment. It is unattractive to animals, which might otherwise try and eat it, and the hairs reflect sunlight and limit evaporation.

Threat

Because of its attractive appearance, this cactus is popular with collectors. Adult plants are dug up and collected for export. Under the CITES convention the international trade in this species is prohibited - unfortunately with little effect because a ‘legally protected’ status often carries little weight in Mexico. At Christmas time the plant is also collected by locals to be sold on street stalls as decorations for nativity cribs. As a result of this want for collecting, numbers of this species have rapidly declined.