Lophophora williamsii (Lem. ex J.F.Cels) J.M.Coult., known under the vernacular name peyote, is one of the most popular and well-known cactus because of its powerful psychoactive properties. Nonetheless, the authority of its basionym, Echinocactus williamsii Lem. ex J.F.Cels, has erroneously been attributed to Joseph zu Salm-Reifferscheid-Dyck and dated from 1845. Herein, we bring to light that the first description was provided by the French horticulturist Jean François Cels in 1842. A historical review of the nomenclature behind this species is provided and the name neotypified. Given that the later isonym by Salm-Reifferscheid-Dyck is being proposed for conservation, the implications of our finding are discussed.