Ferocactus emoryi has a confused taxonomic history. The name is based on Echinocactus emoryi, which was published twice by Engelmann, each involving a different species. Engelmann’s first use of E. emoryi [in W. H. Emory]---applied to a population of Ferocactus wislizeni in eastern Arizona---is rejected as provisional and therefore invalid. However, Engelmann’s second use of E. emoryi was a valid publication, and it unambigously pertains to the species in southwestern Arizona that Britton and Rose unncecessarily re-named as Ferocactus covillei.