Molecular phylogenetic reconstruction of Osmanthus Lour. (Oleaceae) and related genera based on three chloroplast intergenic spacers

Although polyphyly of Osmanthus has been suggested by different authors, the conclusions of previous studies have lacked robust support due to limited sampling or a paucity of phylogenetic characters. In this study, the phylogeny of Osmanthus was explored using sequences of three informative chloroplast regions (psbJ-petA, rpl32-trnL and rps16-trnQ), including all the five sections of the genus and eight closely related genera. The results confirm that Osmanthus, as presently circumscribed, is a polyphyletic group, containing three or four distinct lineages, i.e. sect. Leiolea (lineage I), sect. Notosmanthus (lineage III), sects. Osmanthus (excluding O. decorus), Siphosmanthus and Linocieroides (lineage IV), and an uncertain lineage including only O. decorus (lineage II). These results emphasize that the generic delimitation within subtribe Oleinae is in need of revision. In addition, this study found that the four cultivar groups of sweet osmanthus formed a paraphyletic clade, implying that cultivated sweet osmanthus might originate from several species.