The Dichrostachys group includes five genera of legumes with centers of diversity in Madagascar and subtropical North America. The New World genera have been well-studied, but species and generic limits are poorly understood in the rarely collected Malagasy genera. The proposed research will investigate evolutionary relationships among species in the five genera, integrating data from morphology, pollen, chloroplast DNA, and floral development. A phylogenetic tree will serve to clarify the generic limits, as well as provide a framework for study of the evolution of pollen and floral development in legumes. This study should also provide new insights into the biogeographic relationships of tropical North American legumes. Some neotropical species in this group are being developed as forage legumes, and one temperate species as perennial food crop. It is possible that the as yet unstudied Malagasy species could likewise provide food and forage legumes. In addition, the proposed field work in Madagascar will contribute primary data on the infrequently collected legume flora of Madagascar. This study represents a significant development in the use of molecular character systems in the Mimosa subfamily of legumes, and is the first time that characters involving floral development have been intergrated with morphological and molecular characters in a systematic analysis.
