Concept
Yam is the common name for some plant species in the genus Dioscorea (family Dioscoreaceae) that form edible tubers. The tubers of some other species in the genus, such as D. communis, are toxic. Yams are perennial herbaceous vines cultivated for the consumption of their starchy tubers in many temperate and tropical regions, especially in West Africa, South America and the Caribbean, Asia, and Oceania. The tubers themselves, also called "yams", come in a variety of forms owing to numerous cultivars and related species. Yams were independently domesticated on three different continents: Africa (D. rotundata), Asia (D. alata), and the Americas (D. trifida). The name "yam" appears to derive from Portuguese inhame or Canarian Spanish ñame, which derived from West African languages during trade. However in Portuguese, this name commonly refers to the taro plant (Colocasia esculenta) from the genus Colocasia, as opposed to Dioscorea. The main derivations borrow from verbs meaning "to eat". True yams have various common names across multiple world regions. In some places, other (unrelated) root vegetables are sometimes referred to as "yams", including: In the United States, sweet potatoes (Ipomoea batatas), especially those with orange flesh, are often referred to as "yams" In Australia, the tubers of the Microseris lanceolata, or yam daisy, were a staple food of Aboriginal Australians in some regions. In New Zealand, oca (Oxalis tuberosa) is typically referred to as "yam". In Malaysia and Singapore, taro (Colocasia esculenta) is referred to as "yam". In Africa, South and Southeast Asia as well as the tropical Pacific islands Amorphophallus paeoniifolius is grown and known as "elephant foot yam". A monocot related to lilies and grasses, yams are vigorous herbaceous, perennially growing vines from a tuber. They are native to Africa, Asia, and the Americas. Some 870 species of yams are known, a few of which are widely grown for their edible tuber but others of which are toxic.
