| Three main areas of study are covered by this dissertation: phylogenetic relationships within Chloridoideae based upon molecular evidence, patterns of codon usage and saturation in functional domains of ndhF from a sampling of Chloridoideae, and relationships within core Monanthochloinae as inferred from molecular, anatomical, and micromorphological evidence.; Analyses of a combined data set of ITS (nrDNA), trnL-F and ndhF (both cpDNA) provide strong support for the following order of divergence within Chloridoideae: Triraphis, an Eragrostis clade, and a Sporobolus clade. These are followed by two clades, one is comprised of primarily Old World and cosmopolitan taxa and the other is primarily New World. From Monanthochloinae, Aeluropus and Swallenia are not supported as members of the subtribe. There is strong support for a core Monanthochloinae of Distichlis, Monanthochloe, and Reederochloa. Additionally, this study provides a robust estimate of relationships that will help to reorder tribal and subtribal assignments within Chloridoideae.; Different patterns of amino acid and saturation were observed within the functional domains of ndhF. Codon usage in terminal taxa is not statistically significantly different from that inferred for an ancestral node. Variation is non-randomly distributed across the molecule and between functional domains. Lumenal domains are more variable and stromal and transmembrane domains are more highly conserved.; There is conflict between ITS (nrDNA) and the combined chloroplast ( trnL-F and ndhF) phylogenies in the position of three South American endemics (Distichlis humilis, D. laxiflora, and D. scoparia) within core Monanthochloinae. Additional study is required to correctly place these taxa within the clade. However, there are many characters that unite core Monanthochloinae: whole plant---dioecy, growth in saline/alkali soils, rhizomes and/or stolons, lemma nerve number of 7 to 13; leaf blade transection---colorless cells between all vascular bundles, bulliform cells similar in shape to colorless cells, metaxylem narrow, papillae on abaxial and adaxial surfaces, blades rarely flat slightly to strongly rolled; lemma micromorphology---abundant papillae frequently in pairs on adjacent long and short cells, overarching complexes of papillae surrounding microhairs and stomates with a single papilla on each subsidiary cell. |
