Stenocactus multicostatus

Stenocactus multicostatus, the brain cactus, is a member of the cactus family native to the deserts of Mexico, and is popular in the gardening community. It has gained the Royal Horticultural Society's Award of Garden Merit.

Description
It grows single plant body is spherical to somewhat cylindrical up to 2.5 in (6 cm) tall, 2.4 to 4 in (6–10 cm) wide. It has no fewer than 120 very thin, sharp-edged, pressed, wavy ribs, between which there are narrow furrows. It has nearly 100 thin ribs around the outside, each with six to nine spines. Three white, papery, curved central spines arise from the areole, which are up to 3 centimeters long and have a square cross-section. The four marginal spines are glassy white, upright or slightly curved. The crown is covered by a thin, whitish wool. The upper spines are wider, at 1.6 to 3.2 in (4–8 cm) long, while the lower ones are shorter, at 0.2 to 0.6 in (5–15 mm) long. The flower is white to purple, 0.8 to 2 in (2–5 cm) in diameter with many stamens. The scales of the ovary are broadly ovoid, pointed to pointed, very thin, more or less papery and fall off early.

Distribution
Though it has only been reported in the shrublands of Chihuahua, Coahuila, Durango, Nuevo León, San Luis Potosí, Zacatecas, and Tamaulipas, it has yet to be assessed using the IUCN Categories and Criteria because its taxonomy is still unclear.

Taxonomy
The first mention as Echinocactus multicostatus comes from 1890. Nathaniel Lord Britton and Joseph Nelson Rose assigned Echinocactus multicostatus as Echinofossulocactus multicostatus to the genus Echinofossulocactus, which they newly established in 1922. At the same time they published the first description of two species collected by Francis Ernest Lloyd (1868–1947). Echinofossulocactus lloydii from Zacatecas and Echinofossulocactus zacatecasensis from northern Zacatecas are now considered synonyms. In 1929, Alwin Berger placed the species described by Britton and Rose in Illustrated Handbooks of Succulent Plants: Cacti in the genus Stenocactus. Another synonym Echinofossulocactus erectocentrus was published invalidly by Curt Backeberg in 1961.