Old lady cactus

Description

Mammillaria hahniana, the old lady cactus, is a species of flowering plant in the family Cactaceae, native to central Mexico. It grows to 25 cm (10 in) tall by 50 cm (20 in) broad. The solitary spherical stems, 12 cm in diameter, are covered in white down and white spines. Reddish purple flowers are borne in spring and summer, sometimes forming a complete ring around the apex of the plant. Its status is listed as "Near Threatened" by the IUCN Red List. Mammillaria hahniana is one of several Mammillaria species to be cultivated. In temperate regions it must be grown under glass with heat. However, some growers report that it is quite hardy down to −5 °C (23 °F) or even −10 °C (14 °F). Like all cacti it must be kept dry in winter, and fed and watered during the active growth cycle in summer. Increasing quite readily and flowering at a relatively early age, it is a suitable subject for domestic cultivation. It has gained the Royal Horticultural Society's Award of Garden Merit. Mammillaria is one of the largest genera in the cactus family (Cactaceae), with currently 200 known species and varieties recognized. Most of the mammillaria are native to Mexico, but some come from the southwest United States, the Caribbean, Colombia, Venezuela, Guatemala and Honduras. The common name "pincushion cactus" refers to this and the closely related genus Escobaria. The first species was described by Carl Linnaeus as Cactus mammillaris in 1753, deriving its name from Latin mammilla, "nipple", referring to the tubercles that are among the distinctive features of the genus. Numerous species are commonly known as globe cactus, nipple cactus, birthday cake cactus, fishhook cactus or pincushion cactus though such terms may also be used for related taxa, particularly Escobaria. The distinctive feature of the genus is the possession of an areole split into two clearly separated parts, one occurring at the apex of the tubercle, the other at its base. The apex part is spine bearing, and the base part is always spineless, but usually bears some bristles or wool. The base part of the areole bears the flowers and fruits, and is a branching point. The apex part of the areole does not carry flowers, but in certain conditions can function as a branching point as well.