The objective of this study is the revision of the fifteen species currently referred to Lennea, Hybosema, Gliricidia, and Yucaratonia. This will stabilize the generic classification of this portion of the tribe Robinieae and better estimate the phylogenetic position of these species within it. These species form a distinctive element of the dry tropical forests in North America; however, two species occur in tropical rain forest and one occurs in South America. Economic uses of these species are many and include construction materials from the wood, livestock fodder from the copious leaf production, and "living" fences around agricultural fields and private dwellings. The culmination of this study will be a monograph summarizing the classification, phylogeny, geographic distribution, and economic value of each species. An analysis of taxonomically informative restriction site mutations from the chloroplast genome will be combined with classical taxonomic methods. Further assessing the phylogenetic position of these species in the tribe Robinieae is important because an increased understanding of the phylogenetic relationships within Robinieae will have a bearing on our knowledge of the origins and biogeography of the North American tropical flora. Robinieae is one of the largest papilionoid tribes well represented in tropical and subtropical North America. Current evidence suggests it may have been derived from Asiatic ancestors during the Paleocene or Eocene rather than from South American ancestors in more recent times. Such phylogenetic studies of other plant groups centered in the North American tropics will be essential for understanding the origins of this biota.
