An extensive list of synonomy is available (G. C. K. Dunsterville and L. A. Garay [1959]–1976, vol. 3), but after discussions with Phillip Cribb (pers. comm.), we suspect that the African and Asian synonyms represent different species (see also P. J. Cribb 1984). For this reason, we have excluded them from the list, even though some of them are often used for neotropical plants. Furthermore, Polystachya concreta is not as widespread in the Neotropics as formerly believed; it is absent from Mexico and Central America (J. T. Atwood, G. Carnevali F.-C., R. L. Dressler, pers. comm.).
Cranichis luteola Swartz and Polystachya luteola (Swartz) Hooker are not legitimate names.