Du Zhong, the bark with silver threads
Du Zhong is not a description but a man’s name: according to a legend reported by Li Shizhen, a certain Du Zhong took this bark and attained the Dao. Break a piece of bark, and fine silvery-white threads stretch between the two halves without snapping: a natural rubber, which is both its signature and its first quality criterion. The tree, Eucommia ulmoides, is the only living species of its family, a “living fossil” that the ice ages confined to central and western China. Only part of the bark is taken, from April to June, from trees fifteen to twenty years old, so that the tree survives; its reference growing regions are Sichuan and Guizhou.
Supplementing the Liver and the Kidney
In traditional Chinese medicine, eucommia bark is warm and sweet: sweetness supplements, warmth supports the Yang, and Du Zhong combines the two to carry them towards the lower body. It is associated with the Liver and the Kidney, which go as a pair in tradition: the Liver governs the tendons, the Kidney governs the bones. It nourishes the Kidney Yang and the Liver Blood, which together hold up the lower body, and tradition makes it the herb of the lower back, which is called “the residence of the Kidney”.
Strengthening tendons and bones, in depth
From this follows its second action: when the Kidney is full, the bones are solid; when the Liver is full, the tendons are vigorous. Among neighbouring herbs, it is the most purely tonic, the one preferred when the deficiency is deep and long-standing. It forms a classic pair with Xu Duan: the bark goes more to the Kidney Qi and the bones, while dipsacus root connects the tendons and moves the Blood. It is also found in Du Huo Ji Sheng Tang, where it gives the frame back its solidity. Its reference form is salt-processed bark: saltiness, says tradition, leads downwards, to the Kidney.
Key benefits
Liver & Kidney supported
Sweet and warm, eucommia bark supplements the Liver and the Kidney and, according to TCM, restores the energy that holds up the lower body.
Lower back & knees
The herb of the lower back in Chinese tradition, it supports lower back and knee comfort.
Kidney Yang & deep warmth
It nourishes the Kidney Yang and gently warms the lower body.
