Pediocactus sileri (Engelm. ex J.M. Coult.) L.D. Benson

Pediocactus sileri (Engelm. ex J.M. Coult.) L.D. Benson. Pediocactus sileri is a rare species of cactus known by the common names Siler's pincushion cactus and gypsum cactus. It is native to southwestern Utah and northwestern Arizona in the United States. It is limited to a specific type of soil, individuals are often spaced far apart, and the species is threatened by a number of human activities such as off-road vehicle use, poaching, and uranium mining. This is a federally listed threatened species of the United States.