An overview of the genus Osmanthus (Oleaceae) in Vietnam, with two new records and lectotypifications

An overview of the genus Osmanthus (Oleaceae) in Vietnam is provided. Four species are recognized, of which O. heterophyllus and O. yunnanensis are newly recorded for the country. Results of a molecular phylogenetic study are reported, and employed for clarification of the species idendity of the Vietnamese collections assigned to O. fragrans. In addition, uncertainties in phylogenetic relationships between the sections of Osmanthus are highlighted. For each species, taxonomic and nomenclatural notes are given, along with geographical distribution and analytical illustrations; accounts of the two newly recorded species are supplemented by morphological descriptions and notes on their ecology and phenology. Lectotypes are designated for three names currently treated within the genus Osmanthus. A key for identification of the Vietnamese species of Osmanthus is presented.