Dioscorea villosa

Dioscorea villosa is a species of twining tuberous vine which is native to eastern North America. It is commonly known as wild yam, colic root, rheumatism root, devil's bones, and fourleaf yam. It is common and widespread in a range stretching from Texas and Florida north to Minnesota, Ontario and Massachusetts.

Description

A climbing yam plant. It can be 5 m tall. It keeps growing from year to year. It has slender rhizomes. They are twisted, long and woody. The leaves are simple. The stem has bulbils in the axils of leaves. The leaves are heart shaped and 5-10 cm long. The flowers are small and yellow-green. The are in drooping spikes in the axils of leaves. Male and female flowers are borne separately. The fruit is a capsule that in longer than wide. The seeds are winged at the base.

Edible Uses

The tubers are eaten cooked. Some caution should be exercised — see medicinal uses for relevant information.

Traditional Uses

The tubers are boiled then cut in pieces and washed in running water to remove the toxic element. The tubers are eaten whole or pounded into flour for bread.

Medicinal Uses

The roots contain diosgenin, as do the roots of many other members of this genus. Diosgenin is widely used in modern medicine to manufacture progesterone and other steroid drugs, employed as contraceptives and in treating disorders of the genital organs, as well as conditions such as asthma and arthritis. The roots are anti-inflammatory, antispasmodic, cholagogue, diaphoretic, and vasodilator, and act as a visceral relaxant. The plant is considered one of the best and fastest remedies for bilious colic, is particularly helpful for the nausea of pregnant women, and has been used to ease the pain of childbirth. It is also taken internally for arthritis, irritable bowel syndrome, gastritis, gall bladder complaints, and painful menstruation. The root is harvested in autumn and dried for later use, but should not be stored for longer than one year as it is likely to lose its medicinal virtues. When taken fresh, the root can cause vomiting and other side effects, so caution is advised. The root, harvested in September, is also used to prepare a homeopathic remedy primarily used in the treatment of infant colic.

Known Hazards

Edible species of Dioscorea have opposite leaves whilst poisonous species have alternate leaves. Use of the fresh plant can cause vomiting and other side effects. Known to cause headaches, menstrual irregularities & acne. May cause hair loss & oily skin. Avoid during pregnancy. Avoid in patients with cancers of the breast, ovaries, prostate & uterus.

Distribution

It is a temperate plant. It is best in rich, moist soils. It needs a protected sunny position. It is resistant to frost but damaged by drought. In Assam is grows up to 1,600 m above sea level.

Where It Grows

Asia, Australia, Bangladesh, Brazil, Canada, Europe, Himalayas, India, North America*, Northeastern India, Turkey, Türkiye, USA,

Cultivation

An easily grown plant, succeeding in a fertile well-drained soil in a sunny position or light shade. Prefers a rich light soil. Plants are hardy to at least -15°c. Plants produce tubercles (small tubers that are formed in the leaf axils of the stems), and can be propagated by this means. A climbing plant that supports itself by twining around the branches of other plants. This is a highly polymorphic species, some botanists dividing it up into several species. Dioecious. Male and female plants must be grown if seed is required.

Propagation

Sow seed in March to April in a sunny position in a warm greenhouse, barely covered. Germination takes 1–3 weeks at 20°C. Prick out seedlings once large enough to handle and grow on in the greenhouse for their first year, then plant out in late spring as new growth begins. Basal stem cuttings can be taken in summer. Divide in the dormant season only — never when in growth. The plant often produces several shoots; the top 5–10cm of root below each shoot can be potted up as a new plant, while the lower portion can possibly be eaten. Tubercles forming in the leaf axils are harvested in late summer to early autumn when approximately pea-sized and detaching freely. Pot up immediately into individual containers in a greenhouse or cold frame and plant out in early summer when actively growing.

Other Uses

None known.

Other Information

It is a cultivated food plant.

Notes

This yam is used for contraceptives. There are about 650 species of Dioscorea.

Synonyms

Also Known As

Gam hakai, Kadawa kand, Kadia kand, Kath alu, Kedvo kand, Magiya, Mano kand, Munia, Thaphu-nairo, Vaj kand, Wild yam

References (23)

• Ali, A. M. S., 2005, Homegardens in Smallholder Farming Systems: Examples from Bangladesh. Human Ecology, Vol. 33, No. 2 pp. 245-270 (Would need to check species!)
• BHARGAVA, (As Dioscorea quinata)
• Bodkin, F., 1991, Encyclopedia Botanica. Cornstalk publishing, p 345
• Bremness, L., 1994, Herbs. Collins Eyewitness Handbooks. Harper Collins. p 278
• Brown, D., 2002, The Royal Horticultural Society encyclopedia of Herbs and their uses. DK Books. p 194

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