Eucommia bark comes from the eucommia, or hardy rubber tree. This herb is the trunk bark of Eucommia ulcommia ulmoides Oliv., deciduous tree of the family Eucommiaceae. Native to China, it is grown in the mountainous regions. The tree is a member of the rubber family and is found in the Sichuan, Yunnan, Guizhou and Hubei provinces of China. Mature trees can reach a height of 50 feet; however, the tree is not killed to obtain the bark. Instead, small patches are peeled away from trees 10 over 10 years old in the late summer and early autumn. The inner bark contains a white, rubberish liquid that accounts for eucommia's healing properties.
The tree grows to 12 m by 8 m at a fast rate. It is in flower in April, and the seeds ripen from September to October. The flowers are dioecious (individual flowers are either male or female, but only one sex is to be found on any one plant so both male and female plants must be grown if seed is required). The plant cannot grow in the shade. It requires moist soil.
In China, eucommia is produced mainly in Sichuan, Yunnan, Guizhou, Hubei and Shannxi provinces. The bark is stripped off between April and June. After scraping off the cork, the bark pieces are piled up to be sealed till purplish brown, and dried in the sun. When using, it is cut into segments or stir-baked with salt.
In traditional Chinese medicine, eucommia bark has sweet, warm properties. It is associated with the liver and kidneys, and is considered the primary herb used to increase yang functions in the body. Eucommia bark strengthens the bones and muscles, heals injured and weakened tissues, and can treat lower back and leg pain, stiffness and arthritis.
In addition to its healing effects, eucommia has the ability to lower blood pressure; most Chinese formulas used to lower blood pressure contain at least some amount of eucommia. It is also given to pregnant women to calm the fetus and prevent miscarriage.
