Echinopsis Zucc. in Abh. Math.-Phys. Cl. Königl. Bayer. Akad. Wiss. 2: 675. 1837 sec. Hunt (2006)
  • =Reicheocactus Backeb. in Cactaceae (Berlin) 1941(2): 76. 1942 syn. sec. Hunt (2006)
  • =Leucostele Backeb. in Kakt. And. Sukk. 4: 1. 1953 syn. sec. Hunt (2006)



The present wide circumscription of Echinopsis goes back to the mid-1970s. First indications that this broad Echinopsis is polyphyletic were found by Lendel & al. (2006) and Ritz & al. (2007), and Schlumpberger & Renner (2012) in their deeply sampled study indeed found vast polyphyly and paraphyly throughout most of the subtribe Trichocereinae. Species of Echinopsis were scattered over eight different clades and interspersed with species of Acanthocalycium, Arthrocereus, Cephalocleistocactus, Cleistocactus, Borzicactus, Denmoza, Espostoa, Haageocereus, Harrisia, Matucana, Mila, Oreocereus, Oroya, Pygmaeocereus, Rauhocereus, Samaipaticereus, Weberbauerocereus, and Yungasocereus, all of which are part of a highly supported clade (100% BS).
To transform their results into a formal classification of monophyletic genera is not an easy task. It would either mean to further broaden an already very heterogeneous genus by including the genera mentioned above or to accept about a dozen segregates (valid generic names are at hand).
Nevertheless, maintaining Echinopsis (sensu Hunt 2006) is rather not an option, as it is clearly polyphyletic and should be split up. The necessary new combinations are already available (Schlumpberger 2012); a fully revised generic circumscription is still to be published.