Molecular phylogeny of Old World Trifolium (Fabaceae), based on plastid and nuclear markers

Phylogenies of Old World Trifolium species were constructed using nucleotid e sequence data of the internal transcribed spacers (ITS) of nuclear riboso mal DNA and chloroplast DNA restriction site data from PCR-amplified genes and genic regions (rbcL, trnK, and rpoC1-C2). Biogeography, morphological e volution, and the existing classification for Trifolium were examined. The genus Trifolium is strongly supported as monophyletic, however, only one sm all section (Chronosemium) is monophyletic, although the data are in confli ct regarding its placement. The two largest sections of the genus, Sects. L otoidea and Trifolium, are not supported as monophyletic, as currently circ umscribed. Many members of Sect. Lotoidea are basal within the genus, suppo rting previously-proposed hypotheses concerning plesiomorphic morphological characters and a Mediterranean-Mideast biogeographic origin of the genus.