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SUBJECT: |
Yam (Dioscorea alata) |
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Aracaria References: |
October,2004 | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
 True yams (Dioscorea spp., Dioscoreaceae) are the third most important tropical "root" crop after cassava (Manihot esculenta, Euphorbiaceae) and sweet potato (Ipomoea batatas, Convolvulaceae). This is especially true in West Africa, parts of Central America and the Caribbean, the Pacific Islands, and Southeast Asia. Other important starchy "root" crops are taro and dasheen (Colocasia esculenta, Araceae), the source of Polynesian poi, arrowroot (Maranta arundinacea, Marantaceae), and achira (Canna edulis, Cannaceae). The true yam is about 20 percent starch and as a food is very similar to a potato. The generic name commemorates Dioscorides, the ancient Greek physician and naturalist (1st Century AD). Dioscorides authored the classic De Materia Medica, a five volume reference of several thousand plant drugs that was used for 15 centuries. The most commonly cultivated edible yams are D. rotundata and D. cayensis in Africa, D. alata and D. esculenta in Asia, and D. trifida in the New World, although many cultivated varieties are known. They are climbing perennial vines with shiny, heart-shaped leaves, arising from large underground stems that are technically called tubers rather than roots. Like a potato, the tubers can be propagated by planting sections containing the "eyes" or buds; however, harvesting them is a laborious task because the tubers are deeply buried. Dioscorea is a large genus with more than 600 species. An African species called elephant's foot or Hottentot's bread (D. elephantipes) produces a massive basal stem (caudex) weighing up to 700 pounds (318 kg). The above-ground part of this caudex resembles the shell of a tortoise; hence the common name of "turtleback plant." Like other caudiciform xerophytes (desert plants with enlarged basal stems), the vine relies on carbohydrates and moisture stored in its stem during extended periods of drought. During severe drought conditions the gigantic tuberous stems are eaten as famine food by Hottentots. Luckily for the Hottentots, the tuberous stems are thoroughly cooked because they contains toxic saponins that are broken down during the heating process. Although not a common vegetable, this plant would easily take the record of "World's Largest Vegetable." Another unusual African yam is the air potato (Dioscorea bulbifera). It has small or no subterranean tubers, but instead develops large, liver-shaped aerial tubers up to four pounds (2 kg) each. In New Guinea and Melanesia special ceremonial yams weighing over 120 pounds (54 kg) are grown to reflect the grower's status in the community. The yams are used for gifts and ritualized exchanges. A yam festival is held at harvesttime during which the tubers are covered by elaborate woven masks. There are reportedly yams in tropical Asia and the South Pacific that are much larger. In fact, there is one rather dubious, unconfirmed report of an enormous yam on the island of Pohnpei that was 10 feet (3 m) in length and weighed up to 1500 pounds (680 kg). Rumors have it that at least 10 people were required to carry it. REMEMBER THAT THIS RECORD IS UNSUBSTANTIATED AND MAY NOT BE TRUE.
(from waynesword)
YAM LINKS Known Yam Plant Viruses Medicinal Properties Chinese Yam Medicinal NAME English: Chinese yam, asiatic/white yam, potato yam, winged yam Arabic: batata maee Chinese: da shu, tai shue, shuyu Danish: yans Filipino: ubi French: igname de chine, i. ailée, pacala German: Yamswurzel, Wasseryam Hindi: ratalu, chupri alu, khamatu Italian: igname Japanese: daisho Malay: ubi kemali Portuguese: cará de Angola, c. branco, inhame bravo, cará da terra Spanish: ñame, de agua, ñ. branco, cará branco Thai: huabon Vietnamese: khoaimó CLASSIFICATION Kingdom Plantae – Plants -Subkingdom Tracheobionta – Vascular plants --Superdivision Spermatophyta – Seed plants ---Division Magnoliophyta – Flowering plants ----Class Liliopsida – Monocotyledons -----Subclass Liliidae – ------Order Liliales – -------Family Dioscoreaceae – Yam family --------Genus Dioscorea L. – yam ---------Species – water yam |
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