Eucommia ulmoides

Eucommia ulmoides is a species of small tree native to China. It belongs to the monotypic family Eucommiaceae. It is considered vulnerable in the wild, but is widely cultivated in China for its bark and is highly valued in herbology such as traditional Chinese medicine.

Description

A deciduous tree. It grows 20 m high. It is a broadly spreading tree. The bark is pale grey and deeply cracked. The leaves are oval and 20 cm long by 9 cm wide. They are leathery and taper to the tip. There are teeth around the edge. The leaves are glossy and dark green and droop on thin shoots. The side veins are prominent. The male and female flowers are on separate plants. The flowers are very small and without petals. They grow on old shoots. The fruit are green and winged. They occur in clusters and are 4 cm long. Each key contains a seed. The leaves have a rubbery latex.

Edible Uses

Young leaves are edible. No further details are given.

Traditional Uses

The bark is used to flavour pork and chicken. It is also added to wines. The inner bark is fermented before drying or roasting.

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Medicinal Uses

Known as Du Zhong in China, Eucommia ulmoides is considered one of the 50 fundamental herbs in Chinese herbalism. It is regarded as an excellent tonic for the kidneys and liver, thought to act specifically on the lower part of the body. The stem bark is analgesic, anticholesterolemic, aphrodisiac, depurative, diuretic, hepatic, hypotensive, sedative, tonic, and vasodilatory. It lowers blood pressure — stir-fried bark is more effective than raw, and a decoction is stronger than a tincture — and reduces cholesterol absorption. In a clinical trial involving 119 people, 46% of those treated with the herb showed a significant reduction in blood pressure, though it appears to have little effect in cases of severe hypertension. It is used to treat impotence, frequent urination, lumbago, weakness of the lower body, aching back and knees, hypertension, and threatened abortion. The flowers and fruit are astringent.

Distribution

It is a temperate plant. It is hardy. It grows in the mountain forests of China. It grows between 100-2,000 m above sea level. It suits hardiness zones 5-10. It is frost resistant but cannot tolerate drought. Arboretum Tasmania. National Arboretum Canberra.

Where It Grows

Asia, Australia, Central Asia, China, Korea, Tajikistan, Tasmania,

Cultivation

Succeeds in any well-drained moisture retentive soil in full sun with shelter from cold winds. Prefers a good loamy soil. A fast growing and very cold-tolerant tree, withstanding temperatures down to about -20°c. Trees are commonly cultivated in Russia and China, both for gutta percha and for the medicinal used of the stembark. By using different solvents it is possible to obtain both of these products and the residue is then used for energy production. This species is the only hardy rubber tree that can be grown outdoors in Britain. Dioecious. Male and female plants must be grown if seed is required.

Propagation

Seed is best sown as soon as it is ripe in a cold frame. Stored seed should be stratified for 3 months at 2°c. Germination is usually good and occurs in the first spring. When large enough to handle, prick seedlings out into individual pots and grow on in a greenhouse through the first winter. Plant out into permanent positions in late spring or early summer, after the last expected frosts. Alternatively, take cuttings of half-ripe wood in July/August and root in a frame.

Other Uses

A rubber is obtained from the sap but not in commercially viable quantities. The leaves contain 3% dry weight of gutta-percha, a non-elastic rubber used for electrical wire insulation; gutta-percha is found in all parts of the tree and is extracted using alcohol. The wood is used for making pattens — a type of shoe with raised soles.

Other Information

It is a popular herb.

Notes

There is only one Eucommia species. There is only one genus in the family. A form of rubber is extracted from the tree. It is used in medicine. The bark contains aucubin.

Also Known As

Du zhong, Tou chong, Tu-chung

References (14)

• Bremness, L., 1994, Herbs. Collins Eyewitness Handbooks. Harper Collins. p 55
• Brown, D., 2002, The Royal Horticultural Society encyclopedia of Herbs and their uses. DK Books. p 208
• Burkill, I.H., 1966, A Dictionary of the Economic Products of the Malay Peninsula. Ministry of Agriculture and Cooperatives, Kuala Lumpur, Malaysia. Vol 1 (A-H) p 972
• Coombes, A.J., 2000, Trees. Dorling Kindersley Handbooks. p 145
• Cundall, P., (ed.), 2004, Gardening Australia: flora: the gardener's bible. ABC Books. p 578