Since the publication of Mez (1889), there has been no large-scale, taxonomic treatment of the New World species of the family Lauraceae. Because amny species are of economic importance, particular attention should be paid to this large group of tropical plants. Expeditions to the tropics in past decades have brought out much new material which has been treated, for the most part, in regional publications. In addition to these, monographic study is essential in order that phylogenetic, taxonomic, and nomenclatural problems may be more easily recognized and in many cases resolved satisfactorily. It is for these reasons that the research on the genus Persea here presented was undertaken.