| dc.description.abstract | First, pollen grains of tribe Sanguisorbeae (Rosaceae, Rosoideae) were examined using scanning electron microscopy in order to identify useful characters in the tribe, test taxonomic and phylogenetic hypotheses among genera, and elucidate pollen character evolution. Aperture number, aperture structure, equatorial shape, and exine sculpturing characters grouped the pollen grains into six types. Microverrucate and striate exine sculpturing patterns support a monophyly of Sanguisorbinae and Agrimoniinae respectively. In Agrimoniinae, evolutionary directions of elliptic to circular equatorial shapes and striate to microverrucate sculpturing are apparent and distinguish Hageniafrom the other genera. Pontoperculate apertures are found only in Sanguisorbinae and support close relationships of Acaena, Cliffortia, Margyricarpus, and Polylepis. In chapter 2, phylogeny and biogeography of Agrimoniinae composed of four monotypic endemics (Aremonia, Hagenia, Leucosidea, and Spenceria) and a worldwide genus (Agrimonia) are constructed from nuclear and plastid sequences (GBSSI-1, trnL-trnF, trnS-trnG-trnG). All nucleotide data support the monophyly of Agrimoniinae with a basal group of the Asian monotypic Spenceria (2n=2x=14), the sister relationship of the African genera Hagenia and Leucosidea, and the monophyly of Agrimonia (2n=4x, 6x, and 8x) + Aremonia (2n=6x). In Agrimonia, nuclear data define a lineage of Asian and American tetraploids (Agrimonia coreana, A. microcarpa, A. parviflora, and A. rostellata). These results suggest that the most recent ancestor of the subtribe distributed in Asia (tethyan) and paleo-migration might have occurred between the Northern and Southern Hemispheres and that polyploidy is a major evolutionary process in Agrimoniinae and Agrimonia. Lastly, the genus Agrimonia is characterized as a monophyletic group of 19 species defined by two unique characters, interrupted pinnately compound leaves and bristly epicalyx segments. Species occur primarily in temperate regions throughout North America, Central America, the West Indies, southern South America, Europe, Asia, and southern Africa. Descriptions, nomenclatural histories, distribution maps, and keys are presented to 19 species and three varieties of A. pilosa. Neotypes of A. hirsuta and A. nipponica, an isolectotype of A. pilosa, and a lectotype of A. villosa are designated. The evolution of polyploidy and 12 morphological characters is evaluated within a phylogenetic framework. | |
