Phylogenetic relationships of New World Vicia (Leguminosae) inferred from nrDNA internal transcribed spacer sequences and floral characters

The approximately 27 New World species of Vicia (tribe Fabeae, family Leguminosae) were classified into four stylar type groups as follows: (1) a laterally compressed and evenly hairy stylar type (Le-type) group, (2) a dorsiventrally compressed and abaxially tufted hairy stylar type (Dabt-type) group, (3) a dorsiventrally compressed and evenly hairy stylar type (De-type) group, and (4) V. leucophaea that is characterized by an arcuate style with a dense ring of stylar hairs at a considerable distance from the stigma. In the present study, the stylar distinctions among the groups were confirmed by morphological and anatomical studies on the stylar characters of representative species of the groups. The phylogenetic positions of these groups were then assessed using molecular phylogenetic analysis based on sequences from the nuclear ribosomal DNA (nrDNA) internal transcribed spacer (ITS) region of the representative species. The New World Le-type stylar group was revealed to be a sister group to the Old World Le-type stylar group. The New World Dabt-type stylar group and V. leucophaea are nested within the Old World Dabt-type stylar group. These New World groups were nested well within the Old World Vicia, suggesting that the New World diversification occurred relatively recently during the evolution of Vicia.