Amur Cork Tree

The Amur cork tree is a tree of the citrus family, native to eastern Asia: northern and north-eastern China, Korea, the Amur and Ussuri regions of Russia, and Japan. Its bark is a major source of huáng bò, one of the 50 fundamental herbs of traditional Chinese medicine, and the plant is called hwangbyeok in Korean and kihada in Japanese. The Ainu people used its fruit, which they called shikerebe-ni, as a painkiller. In traditional Chinese medicine it has been used for conditions that include dysentery, jaundice and urinary infections, though the article that describes this notes that its medical sourcing is weak. A yellow dye taken from the bark was used across East Asia to colour the paper of sutras and other documents, including the Diamond Sutra, and the dye protected the paper against insects. Outside its home range the tree is considered invasive in much of North America, and the state of Massachusetts lists it as a noxious weed.