The purpose of this project is to: 1) reconstruct a phylogeny for Orcuttieae, a small tribe of vernal pool C4 grasses, using molecular data and 2) use the phylogeny to assess the evolutionary history and pathway modifications of C4 photosynthesis in this group. Previous work by Keeley (1998) revealed that Orcuttia carries out C4 photosynthesis in aquatic leaves but lacks Kranz anatomy while the remaining genera in the tribe, Tuctoria and Neostapfia have Kranz anatomy. Keeley (1998) proposed that Orcuttia is the most derived genus in the tribe followed by Tuctoria and the earliest derived genus Neostapfia. His hypothesis was based on the lack of Kranz anatomy and other aquatic adaptations. This investigation will test the hypothesis advanced by Keeley (1998) to explain the unique physiology of the Orcuttieae. A phylogeny coupled with the photosynthetic data for this group will elucidate the transition of Orcuttieae from land to an aquatic environment.

Key words: Kranz Anatomy, Molecular Evolution, Orcuttieae, Photosynthesis, Poaceae, Vernal Pools