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

Phylogenies of Old WorldTrifolium species were constructed using nucleotide sequence data of the internal transcribed spacers (ITS) of nuclear ribosomal DNA and chloroplast DNA restriction site data from PCR-amplified genes and genic regions (rbcL,trnK, andrpoC1–C2). Biogeography, morphological evolution, and the existing classification forTrifolium were examined. The genusTrifolium is strongly supported as monophyletic, however, only one small section (Chronosemium) is monophyletic, although the data are in conflict regarding its placement. The two largest sections of the genus, Sects.Lotoidea andTrifolium, are not supported as monophyletic, as currently circumscribed. Many members of Sect.Lotoidea are basal within the genus, supporting previously-proposed hypotheses concerning plesiomorphic morphological characters and a Mediterranean-Mideast biogeographic origin of the genus.