Greek ankistron ‘fishhook’ + Cactus. For the long, hooked central spines. The name is based on Echinocactus subgen. AncistrocactusK.Schum. That subgenus is named for Echinocactus [infragen. unranked] UncinatiSalm-Dyck, which is named for its type species, Echinocactus uncinatus (Latin uncinatus ‘hooked, barbed’).
Note that Britton & Rose placed Echinocactus uncinatus in Ferocactus and designated Ancistrocactus megarrhizus as the type species of this genus. Ancistrocactus Britton & Rose and Echinocactus subgen. AncistrocactusK.Schum. are therefore not the same taxon. The latter name is a synonym of Ferocactus or Glandulicactus.
Ancistrocactus scheeri. Image credit: Michael Wolf / CC BY-SA 3.0
Maarten H.J. van der Meer (2022 Feb 05). Ancistrocactus. Dictionary of Cactus Names. Retrieved from https://www.cactusnames.org/ancistrocactus