Eucommia bark comes from the eucommia tree, or hardy rubber tree, that originates in the Sichuan, Yunnan, Guizhou and Hubei provinces of Central China. It is grown as an ornamental and shade tree that can reach heights up to 60 feet in temperate climates. To obtain the bark of the tree, small patches are peeled away from mature trees in the late summer and early autumn. This allows cultivation of Du Zhong without harming the tree. Wild eucommia trees are rare and are protected; most of the trees used for medicinal purposes are cultivated. The inner bark that is revealed contains a white, rubbery liquid that accounts for eucommia’s healing properties. While this elastomeric sap contains many benefits, it is noted that people with latex allergies may also be allergic to du zhong.
In Chinese Herbal Medicine, Eucommia is considered spicy and sweet; its thermal property in the body is warming. Du Zhong has an affinity for the liver and kidney channels. This affinity lends itself to strengthening muscles and bones and to treat arthritic pain in the lower back and knees. Du Zhong does this by promoting circulation. Du Zhong’s ability to aid in regulating the flow of the qi and blood also proves helpful in lowering high blood pressure. Eucommia is also known as a stabilizer in pregnant women. Eucommia can also be used in a charred form to help calm a “restless fetus” and prevent miscarriage.