Argemone crassifolia G.B.Ownbey is a species of conservation interest for the flora of Chile, as it is known only from its type specimen collected in the Atacama Region in 1925. After almost a century since its discovery, and in the absence of current collections, it was classified as “extinct” by the Ministry of Environment of Chile. This work aimed to obtain a record of this species through searches in the locality where I. M. Johnston collected the type specimen, Quebrada Cañas, within the province of Copiapo. With the information obtained from this record, the original description is complemented, details about its ecology are provided, and a new conservation category is proposed. Finally, the possible systematic and conservation implications of this discovery are discussed.