Dioscorea oppositifolia

Botanical Name :Dioscorea oppositifolia
Family: Dioscoreaceae – Yam family
Genus : Dioscorea L. – yam
Species : Dioscorea oppositifolia L. – Chinese yam
Kingdom : Plantae – Plants
Subkingdom : Tracheobionta – Vascular plants
Superdivision:Spermatophyta – Seed plants
Division : Magnoliophyta – Flowering plants
Class: Liliopsida – Monocotyledons
Subclass : Liliidae
Order : Liliales

Synonyms: Dioscorea batatas£¬Dioscorea opposita (Thunb.), Dioscorea polystachya (Turcz.), Dioscorea divaricata
Common name: Chinese yam, air potato, Shan yao, Shan yam

Habitat :Dioscorea oppositifolia is native to China and was introduced into North America as an ornamental vine. In 1970, it had not yet been documented as escaping from cultivation. By 1986 however, Mohlenbrock (1970, 1986) reports that it had become naturalized and was observed in areas outside of cultivation (Beyerl 2001).

In North America, D. oppositifolia is currently present in: Alabama, Arkansas, Connecticut, Georgia, Illinois, Indiana, Kansas, Kentucky, Louisiana, Maryland, Mississippi, Missouri, New Jersey, New York, North Carolina, Ohio, Oklahoma, Pennsylvania, South Carolina, Tennessee, Vermont, Virginia, and West Virginia (USDA, NRCS 1999). Beyerl (2001) reports that it has now also been documented from Florida.

Dioscorea oppositifolia can survive in a number of different habitats and environmental conditions, but is most commonly found at the edges of rich, mesic bottomland forests, along streambanks and drainageways, and near fencerows (Yayskievych 1999). Initial infestations of D. oppositifolia are generally associated with human-caused disturbances, such as near old homesites and along roadways. From these areas, D. oppositifolia can easily spread into nearby riparian swaths and undisturbed habitats.

Description;
Herbaceous, high climbing vines to 65 feet (20 m) long, infestations covering shrubs and trees. Twining and sprawling stems with long-petioled heart-shaped leaves. Spreading by dangling potato-like tubers (bulbils) at leaf axils and underground tubers. Monocots.

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Edible uses:  Both the tuber and bulbils of D. oppositifolia are edible, although the bulbils are generally not collected and used as food. The edible tuber, which can measure up to 1 m (3 ft) long and weigh up to 2 kg (4.5 lbs) or more if grown in deep loam soils, is flavorful and nutritious. The flavor, according to Plants for a Future (1997), is between a sweet potato and a regular potato. The tuber contains about 20% starch, 75% water, 0.1% vitamin B1, and 10 to 15 mg Vitamin C. It also contains mucilage, amylase, amino acids, and glutamine.

The tuber is sometimes used as an herbal tonic. It stimulates the stomach and spleen and has an effect on the lungs and kidneys. The tuber has been eaten for the treatment of poor appetite, chronic diarrhea, asthma, dry coughs, frequent or uncontrollable urination, diabetes, and emotional instability. Externally, the tuber has also been applied to ulcers, boils and abscesses. It contains allantoin, a cell-proliferant that speeds up the healing process (Plants for a Future 1997).

Leaf juice from D. oppositifolia can be used to treat snakebites and scorpion stings. Its roots contain diosgenin, which is a compound often used in the manufacture of progesterone and other steroid drugs. Dioscorea oppositifolia has also been used traditionally as a contraceptive and in the treatment of various disorders of the genitary (genital?) organs as well as for asthma and arthritis (Plants for a Future 1997).

Dioscorea oppositifolia has been, and is still frequently planted for its ornamental value. The flowers smell like cinnamon and the twining vine is attractive for arbors, trellises, and along porches (Illinois DNR).

Medicinal Uses;
The Chinese yam, called Shan Yao in Chinese herbalism, is a sweet soothing herb that stimulates the stomach and spleen and has a tonic effect on the lungs and kidneys. The tuber contains allantoin, a cell-proliferant that speeds the healing process. The root is an ingredient of “The herb of eight ingredients”, traditionally prescribed in Chinese herbalism to treat hyperthyroidism, nephritis and diabetes.

A gentle tonic, shan yao is prescribed for tiredness, weight loss, and lack of appetite.  The root strengthens a weak digestion, improves appetite, and may help bind watery stools.  It counters excessive sweating, frequent urination, and chronic thirst, and it is also given for chronic coughs and wheezing.  The traditional use of shan yao, indicates a hormonal effect.  It is also taken to treat vaginal discharge and spermatorrhea. The Chinese use the yam to brighten the eyes and as an elixir and an important tonic for the spleen and stomach.  The drug also lowers blood sugar and is used in diabetes.

This is one of several herbs under intensive medical research in China as a tonic restorative for immune deficiency.  The herb helps restore impaired immune functions, stimulates secretions of vital immune factors, and enhances overall immune response throughout the system.

The roots of most, if not all, members of this genus, contains diosgenin. This is widely used in modern medicine in order to manufacture progesterone and other steroid drugs. These are used as contraceptives and in the treatment of various disorders of the genital organs as well as in a host of other diseases such as asthma and arthritis.

Disclaimer:The information presented herein is intended for educational purposes only. Individual results may vary, and before using any supplements, it is always advisable to consult with your own health care provider

Resources:
http://plants.usda.gov/java/profile?symbol=DIOP
http://www.texasinvasives.org/plant_database/detail.php?symbol=DIOP
http://wiki.bugwood.org/Dioscorea_oppositifolia
http://www.herbnet.com/Herb%20Uses_UZ.htm

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