Origin, Distribution, Taxonomy, Botanical Description, Genetics and Cytogenetics, Genetic Diversity and Breeding of Yams (Dioscoreaceae spp.)

Yams belong to the Family Dioscoreaceae, Genus Dioscorea and Species Dioscorea alata L. The name "yam" appears to derive from Portuguese inhame or Canarian Spanish ñame, which derived from Fula, one of the West African languages during trade. The main derivations borrowed from verbs meaning "to eat". True yams have various common names across multiple world regions. Water yam, white yam, winged yam, greater yam=D. alata; air yam, air-potato, bitter yam=D. bulbifera; fiveleaf yam, five-leaved yam=D. pentaphylla; Chinese yam, cinnamon vine=D. polystachya; Zanzibar yam; West African yam=D. sansibarensis. Because it has become naturalized following its origins in Asia, specifically the Philippines, through tropical South America, and the southeastern U.S., D. alata is referred to by many different names in these regions. In English alone, aside from purple yam, other common names include ten-months yam, water yam, white yam, winged yam, violet yam, Guyana arrowroot, or simply yam. Dioscorea alata , also called purple yam, ube or greater yam, among many other names is a species of yam (a tuber). The tubers are usually a vivid violet-purple to bright lavender in color (hence the common name), but some range in color from cream to plain white. With its origins in the Asian tropics, D. alata has been known to humans since ancient times. Yams (family Dioscoreaceae, genus Dioscorea) are climbing perennial monocots with underground, and sometimes aerial, starchy tubers that are grown as a staple food. In Africa, yams are widely consumed in a variety of ways in a number of countries particularly in West Africa. Yams provide the staple foodstuff for millions of people in many tropical and subtropical countries, and are an important secondary food for many millions more. Furthermore, he indicates that apart from the yams that are cultivated as a food crop, there are also wild yams whose tubers are collected for eating in times of food shortages. These wild yams are a reliable standby nutritional backup for a large number of populations. The “bitter yam,” Dioscorea dumetorum (Kunth) Pax, is popular as a vegetable. The wild forms of this species are very toxic and are sometimes used to poison animals when mixed with bait. D. dumetorum is found in Zambia, Zimbabwe, and Mozambique with a considerable number of vernacular names, ranging from “idiya” in Mozambique to “chinkolongo/inkolongo,” “nkansa,” and “ndiya” in Zambia. The tubers are used as a famine food after washing and drying to remove toxins. Taxonomy, Botanical Description, Genetics and Cytogenetics, Genetic Diversity, Breeding, Uses, Nutritional Value and Health Benefits of Yams are discussed.