Concerns with human nutrition and with potential large-scale climatic changes have reinforced arguments for broadened study of new crop plants and their wild taxonomic relatives in the Americas. The grain chenopods (family Chenopodiaceae, genus Chenopodium), ancient crops of the Inca and Aztec, show great promise. They also provide a living record of American Indian agriculture. However, basic taxonomic information is meager regarding geographic distributions, morphological and genetic variation among species and among cultivated and weedy forms, suspected areas of crop origins, and genealogical relationships among the several taxa involved. Using both molecular and morphometric approaches of comparative biology, Drs. Hugh Wilson and James Manhart at Texas A&M University are investigating species, cultivars, and weed races of Chenopodium subsection Cellulata in Mexico and the United Sates. Results will be integrated with their prior studies of South American "quinoa," another indigenous crop complex. New analyses of chloroplast DNA mutational differences will provide data bearing on phylogenetic relationships among these plants. The results will help clarify taxonomic boundaries between taxa, delimit ranges of variation in domesticated and weedy forms, and test ideas about the pre-Columbian origins of these crops and their routes of dispersal.
