Species Notes: The name Sclerocactus sileri listed here under synonyms is not a valid of Pediocactus sileri. In the 2004 publication of The Cactus Family, Anderson had confused Pediocactus sileri with Sclerocactus sileri. This confusion is understandable since these two species are very similar and the natural habitat overlaps. Giving both species the same name was not helpful.
I list the names here under P. sileri even though they are invalid so that those who might be using Anderson's book will find this listing under a name search on this site and thereby be led to this corrective information.