Dioscorea villosa (L)
Synonyms: colic root, rheumatism root, China root, devil's bones, yuma, Mexican wild yam, wilde yamwurzel
Order: Dioscoreaceae
Description: Dioscorea is an herbaceous twining perennial common in the eastern and central United States. Twining in hedges, and over bushes and fences, the thin, woolly, reddish-brown stem grows up to 6m long. The slender, tuberous rootstock is crooked and laterally branched. Broadly ovate and cordate, the leaves are from 5-15cm long and 3-12cm wide, glabrous on top, and finely hairy underneath. They are usually alternate, but the lower leaves sometimes grow in twos and fours. The small, greenish-yellow flowers bloom during June and July, the male flowers in drooping panicles, the female in drooping, spicate racemes. The fruit is a three-winged capsule containing winged seeds.
Parts used: dried rhizome and roots.
Collection: the plant is uprooted in autumn.
Constituents: steroidal saponins (including dioscin and trillin which yield diosgenin), tannins, phytosterols, alkaloids (including dioscorine), starch
Actions: spasmolytic, mild diaphoretic, anti-inflammatory (possibly steroidal), antirheumatic, cholagogue, diuretic, expectorant, relaxant for smooth muscle, mild peripheral vasodilator
Indications: bilious colic, intestinal colic, functional colitis, colonic spasm, dysentery, diverticulitis, acute phase of rheumatoid arthritis, muscular rheumatism, rheumatic inflammatory conditions, cramps and intermittent claudication, cholecystitis, dysmenorrhoea, ovarian and uterine pain.
Therapeutics and Pharmacology: Dioscorea has traditionally been used for easing menstrual cramps and for threatened miscarriage. Its antispasmodic action makes it good for flatulence and colic caused by muscle spasm. The herb also promotes the flow of bile and is sometimes used to ease the colic of gallstones. It's anti-inflammatory action is due to the steroidal saponins, and it is often used for the inflammatory stage of rheumatoid arthritis. It has a diuretic effect which, combined with its antispasmodic action, makes it useful in painful conditions of the urinary tract. Its antispasmodic action also makes it useful for treating poor circulation and neuralgia. It is given for intermittent claudication (pain in the calves caused by spasms in the blood vessels supplying the leg muscles). Dioscorea contains hormonal substances very similar to progesterone.
Combinations: Dioscorea may be combined with Acorus, Chamaemelum and/or Zingiber in a hot infusion for intestinal colic. It can be used with Viburnum opulus and Cimicfuga in rheumatoid arthritis, or with Apium, Althaea, Filipendula, Salix or Menyanthes for the acute stages of rheumatoid arthritis. A decoction with the bark of Salix alba will relieve arthritic pains. It may also be combined with Sambucus and Althaea for the treatment of appendicitis and diverticulitis.
Caution: Dioscorea may be emetic in large doses. It should be avoided during pregnancy unless under professional advice, but may be taken during labour.
Preparation and Dosage: (thrice daily)
Dried root: 2-4g or by infusion or decoction
Liquid extract: 1:1 in 45% alcohol, 2-4ml.
Tincture: 1:5 in 45% alcohol, 2-10ml
Additional Comments: In 1943 the scientist Russell Marker made two kilos of the female hormone progesterone from the wild Mexican yam (D.mexicana). Until 1970, diosgenin derived from the wild yam was the sole source of the hormonal material used to make the contraceptive pill. Many other yams are used as a starter material for hydrocortisones in orthodox eczema creams. D. opposita (shan yao), the Chinese yam, is an important tonic herb. Its main action is on the kidneys, lungs and stomach, and it is included in remedies for asthma, menopausal syndrome, urinary disorders and weak kidney energies. D. hypoglauca (bei xie), or seven-lobed yam, is used mainly for urinary tract infections such as cystitis. Antibacterial and anti-inflammatory, it relieves rheumatoid arthritis. Extracts of bei xie are used in the synthesis of contraceptive pills.
Bibliography
BHMA 1983 British Herbal Pharmacopoeia, BHMA, Bournemouth.
Grieve, M. 1931 A Modern Herbal, (ed. C.F. Leyel 1985), London.
Hoffmann, D. 1990 The New Holistic Herbal, Second Edition, Element, Shaftesbury.
Lust, J. 1990 The Herb Book, Bantam, London.
Mabey, R. (ed.) 1991 The Complete New Herbal, Penguin, London.
Mills, S.Y. 1993 The Essential Book of Herbal Medicine, Penguin, London (First published in 1991 as Out of the Earth, Arkana)
Mills, S.Y. 1993 The A-Z of Modern Herbalism, Diamond Books, London.
Ody, P. 1993 The Herb Society's Complete Medicinal Herbal, Dorling Kindersley, London.
Polunin, M. and Robbins, C. 1992 The Natural Pharmacy, Dorling Kindersley, London.
Wren, R.C. 1988 Potter's New Cyclopaedia of Botanical Drugs and Preparations, C.W.Daniel, Saffron Walden.
