A flavonoid survey of Fraxinus (Oleaceae) in eastern Asia, and the overlooked species Fraxinus hopeiensis T. Tang in northern China

► A survey of 14 flavonoids of 19 Asian taxa showed two chemical groups. ► This chemical approach was useful in the determination of natural groupings of the overlooked Chinese taxon. ► Fraxinus hopeiensis of Hebei has petals and is clearly different from Fraxinus rhynchophylla and Fraxinus chinensis. ► F. hopeiensis should be treated as a distinct species.