''Dioscorea cayenensis'' subsp. ''rotundata'', commonly known as the white yam, West African yam, Guinea yam, or white ñame, is a subspecies of yam native to

Africa Africa is the world's second-largest and second-most populous continent after Asia. At about 30.3 million km2 (11.7 million square miles) including adjacent islands, it covers 20% of Earth's land area and 6% of its total surfac ...

. It is one of the most important cultivated yams.USDA PLANTS profile for ''Dioscorea rotundata''
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Kokoro is a 1914 Japanese novel by Natsume Sōseki, and the final part of a trilogy starting with ''To the Spring Equinox and Beyond'' and followed by '' The Wayfarer'' (both 1912). Set in the Meiji era, the novel tells of the acquaintance between ...

is one of its most important

cultivar A cultivar is a kind of Horticulture, cultivated plant that people have selected for desired phenotypic trait, traits and which retains those traits when Plant propagation, propagated. Methods used to propagate cultivars include division, root a ...

s. It is sometimes treated as separate species from '' Dioscorea cayenensis''.

Domestication

Its wild progenitor is '' Dioscorea praehensilis'' and possibly also '' D. abyssinica'' (by hybridization). Domestication occurred in

West Africa West Africa, also known as Western Africa, is the westernmost region of Africa. The United Nations geoscheme for Africa#Western Africa, United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Gha ...

, along the south-facing Atlantic coast. There is insufficient documentation and insufficient research to determine how long ago that occurred.

Distribution

''D. c.'' subsp. ''rotundata'' is grown in

, including countries such as

Ivory Coast Ivory Coast, also known as Côte d'Ivoire and officially the Republic of Côte d'Ivoire, is a country on the southern coast of West Africa. Its capital city of Yamoussoukro is located in the centre of the country, while its largest List of ci ...

Ghana Ghana, officially the Republic of Ghana, is a country in West Africa. It is situated along the Gulf of Guinea and the Atlantic Ocean to the south, and shares borders with Côte d’Ivoire to the west, Burkina Faso to the north, and Togo to t ...

and

Nigeria Nigeria, officially the Federal Republic of Nigeria, is a country in West Africa. It is situated between the Sahel to the north and the Gulf of Guinea in the Atlantic Ocean to the south. It covers an area of . With Demographics of Nigeria, ...

.Biodiversity and domestication of yams in West Africa: Traditional practices leading to ''Dioscorea rotundata'' Poir.
Roland Dumont ''et al.'' 2005, CIRAD-IPGRI

Linguistics

Blench (2006) reconstructs the tentative Proto-Niger-Congo (i.e., the

most recent common ancestor A most recent common ancestor (MRCA), also known as a last common ancestor (LCA), is the most recent individual from which all organisms of a set are inferred to have descended. The most recent common ancestor of a higher taxon is generally assu ...

of the Niger-Congo languages) root -ku for ''D. rotundata''.

References

Crops originating from Africa Yams (vegetable) Flora of West Tropical Africa Plant subspecies cayenensis subsp. rotundata {{Dioscoreales-stub