Rhus javanica var. chinensis as a new plant origin of propolis from Okayama, Japan.

To directly identify the plant origin of propolis from Takebe-cho (Okayama, Japan), we observed the honeybee behavior. Honeybees scraped sap from the tree, Rhus javanica var. chinensis. We compared the constituents and radical-scavenging activity of this sap and propolis. Their chemical constituents and radical-scavenging activity were comparable. This indicates directly that the plant origin of this propolis is R. javanica var. chinensis.