Maxillaria, the fourth largest genus of neotropical Orchidaceae with ca. 650 species (nine in the Greater Antilles), is vegetatively diverse, and there have been various attempts at reclassification based on patterns of growth. Some species produce exclusively sympodial growths, each terminated by a pseudobulb, others produce monopodial growths lacking pseudobulbs. More curiously, some species are sympodial as juveniles and monopodial as adults, a metamorphosis demonstrating the expected ease of evolutionary change from a species with one growth pattern to a species with another. Mapping growth architecture onto clades based on preliminary cladistic analysis of ITS sequences reveal three features: 1) Maxillaria is paraphyletic with at least Mormolyca and Cryptocentrum nested within; 2) Monopodial habits are derived and have arisen at least five times from sympodial ancestors; and 3) Plant habit may define certain clades but is not useful in others for defining genera. The data suggest two alternatives for reclassifying Maxillaria: 1) To include most if not all genera within a large genus, Maxillaria, if the genus Cryptocentrum can be accommodated within it; and 2) If Cryptocentrum cannot be so accommodated, Maxillaria must be divided into several genera.