Mascagnia is a genus in the Malpighiaceae, a family of about 75 genera of flowering plants in the order Malpighiales. Mascagnia comprises ca. 45 species that occur from northern Mexico to northern Argentina and southeastern Brazil and in the Caribbean in diverse habitats. Mascagnia in the traditional sense of was a highly polyphyletic assemblage, a form-genus based on the lateral-winged samaras. Since the mid-1980s, morphological and molecular studies led to the removal of discordant elements, which were assigned to the genera Adelphia, Aenigmatanthera, Alicia, Amorimia, Calcicola, Callaeum, Carolus, Christianella, Malpighiodes, Niedenzuella, and Psychopterys. In addition, phylogenetic analyses showed that Triopterys is nested within Mascagnia. The species formerly assigned to Triopterys were transferred to Mascagnia, which is now a monophyletic genus. The correct name for the species often called Mascagnia macroptera in the horticulture trade is Callaeum macropterum; the names are not interchangeable. Most of the plants sold in the US under the names Callaeum macropterum and Mascagnia macroptera are actually Callaeum septentrionale.