Echinocactus Link & Otto, Verh. Vereins. Beförd. Gartenbaues Königl. Preuss. Staaten 3: 420. 1827 sec. Vargas-Luna & al. 2018



Phylogenetics: Echinocactus turns out to be paraphyletic in recent molecular studies (Bárcenas & al. 2011; Hernández-Hernández & al. 2011; Vázquez-Sánchez & al. 2013), with E. grusonii Hildm. resolved in a separate clade from the remaining four species. Vargas-Luna & al. (2018) showed that Echinocactus s.l. was paraphyletic with Astrophytum nested within, and E. grusonii resolved as sister to Ferocactus. They re-circumscribed Echinocactus to reflect this well-supported topology and also showed morphological characters to recognize two genera, Echinocactus s.s., and Homalocephala. It is clear that the monotypic Kroenleinia grusonii is not a member of Echinocactus, however, its distinction from Ferocactus is not entirely clear. See Kroenleinia.A
A. Majure, L.C. 2021: Revisions of Cochemiea, Consolea, Coryphantha, Cylindropuntia, Cumarinia, Grusonia, Kroenleinia, Leptocereus, Melocactus, Micropuntia, Opuntia. – In: Korotkova N. & al., Cactaceae at – a dynamic online species-level taxonomic backbone for the family. – Willdenowia 51(2): 250-270