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{{SPlantbox
|familia=Dioscoreaceae
|genus=Dioscorea
|habit=vine-climber
|Min ht metric=cm
|lifespan=perennial
|features=edible
|Temp Metric=°F
|image=YamsatBrixtonMarket.jpg
|image_width=240
}}
:''For the vegetable sometimes called ''yam'' in the United States, see [[sweet potato]]''

{{Inc|
Yam. The name yam properly belongs to the members of the genus Dioscorea, although unfortunately it has been applied for many years in the United States to the large varieties of the sweet potato, Ipomoea Batatas. The name as applied to the sweet potato is thought by some to be a corruption of an African word pronounced "nyam," brought by the negroes who were transported to America in the early days. This word was used for the true yam or other large roots or tubers used for food in Africa and was bestowed by the negroes on the large sweet potatoes in America.

The botany of the cultivated yams has not been cleared up. Many varieties are of mediocre quality, while some are excellent, being superior in flavor and mealiness to almost any other starchy vegetable. Single roots or tubers of some varieties, particularly of D. alata, attain great size, occasionally even reaching 100 pounds or more in weight, and several feet in length. The best varieties, however, are of small size, often less than a pound in weight. Among the best known of these are the yampis of Jamaica and the Isthmus of Panama, and other varieties of similar quality, such as the cush-cush of the Island of Trinidad. The Chinese yam or cinnamon vine, D. Batatas, is of excellent flavor, but on account of its deep-growing habit is very difficult to dig. Several kinds of yam are grown scatteringly in Florida. For further discussion, see Dioscorea.
}}

'''Yam''' is the common name for some species in the genus ''[[Dioscorea]]'' (family [[Dioscoreaceae]]).  These are [[perennial plant|perennial]] [[herbaceous]] [[vine]]s cultivated for the consumption of their starchy [[tuber]]s. There are many [[cultivar]]s of yam.

The [[sweet potato]] (''Ipomoea batatas'') has traditionally been referred to as a ''yam'' in parts of the United States and Canada, but it is not part of the Dioscoreaceae family.

Yam tubers can grow up to 2.5 m (8.2 ft) in length<ref>Huxley, 1992</ref> and weigh up to 70&nbsp;kg (154 lb). 

The vegetable has a rough skin which is difficult to peel, but which softens after heating. The skins vary in color from dark brown to light pink. The majority of the vegetable is composed of a much softer substance known as the "meat". This substance ranges in color from white or yellow to purple or pink in ripe yams.

The tubers can be stored up to six months without refrigeration.