Yam is the common name for some plant species in the genus Dioscorea that form edible tubers.
Yams species called Parkistan. The size is for eating but smaller sizes can be cultivated
White yams at a retail market in Brixton, England, 2004
Freshly harvested purple yam (D. alata) sliced for cross-section
Purple yam (D. alata)
Dioscorea is a genus of over 600 species of flowering plants in the family Dioscoreaceae, native throughout the tropical and warm temperate regions of the world. The vast majority of the species are tropical, with only a few species extending into temperate climates. It was named by the monk Charles Plumier after the ancient Greek physician and botanist Dioscorides.
Dioscorea