Cereus's a genus of cactus. The circumscription of this genus has always been in flux and depends on the authority. Synonymy The following genera have been brought into synonymy with Cereus: Mirabella F.Ritter Piptanthocereus (A.Berger) Riccob. Subpilocereus Backeb. Selected species Cereus peruvianus… (More on Cereus)