SummaryThe genus Melampodium contains 37 species which are distributed throughout Mexico and Central America. Although several evolutionary studies already have been completed on the genus, none has synthesized detailed morphological relationships. A cladistic technique combining features of that of Whiffin and Bierner (1972) and Wagner (1961) is used to construct cladograms. To determine primitive states of 18 qualitative and quantitative characters, four assumptions have been used. A primitive character state: (1) is found in a majority of phenetic groups within the genus (a modification of the “common is primitive” criterion); (2) is found also in the related genus Acanthospermum (out‐group comparison); (3) represents a beginning condition of an evolutionary trend that has occurred frequently in parallel within the Compositae; and (4) is a common morphological condition for the family in which the contrasting state is very atypical and obviously derived. The cladograms indicate that numerous parallelisms in the evolution of morphological features have occurred in Melampodium. These trends correspond well with the known chromosomal lines of x = 9, 10, 11, and 12. Distributional data also reflect a pattern of parallel evolutionary development. Taxa of Melampodium are regarded as advanced distributionally if they: (1) are weedy (being defined as having the broadest distributions); (2) are found on the periphery of the range of the genus; and (3) are found in recently derived habitats, chiefly deserts. Species advanced on distributional grounds are found in all four of the chromosomal lines of the genus. Based on all data, section Melampodium (x = 10) is regarded as most primitive within the genus. Considerable evolutionary development also has occurred within this evolutionary line, however, leading to the highly advanced white‐rayed complex (series Leucantha).