Pilocereus williamsii Scheidw. Dataset GBIF Backbone Taxonomy Rank SPECIES Classification kingdom Plantae phylum Tracheophyta class Magnoliopsida order Caryophyllales family Cactaceae genus Cephalocereus species Cephalocereus senilis Name Homonyms Pilocereus williamsii Lem. Pilocereus williamsii Scheidw. Pilocereus williamsii Scheidw. ex C.F.Först.