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Whatever your supermarket may claim, the “yams” they have for sale are almost certainly not yams. The yam that am is an African tuber not at all related to the native American sweet potato, which is often marketed as a yam. The sweet potato (Ipomoea batatas) is a small thing compared to a true yam, which has orange flesh and a fairly smooth, potatolike skin. I. batatas does have a white-fleshed variety, but it is sold as boniato and not yam. The true yam (Dioscorea spp.) is large, has white flesh (D. rotundata) or yellow flesh (D. cayenensis), and appears only in U.S. markets that offer the full range of tropical tubers. Even these Linnaean names incorporate the confusion that surrounds this extremely valuable plant. By one theory, the yellow and white yams are part of the same “species complex, ” but, van Wyk points out, they do not have the same number of chromosomes.

As the species name implies, the yam owes its scientific name to the very influential medical botanist Pedanius Dioscorides, a first-century Greek born in Asia Minor who traveled as a doctor with the Roman legions in the time of Vespasian and published De Materia Medica in the 60s or 70s. When modern systematic botany honored Dioscorides by naming the yam genus after him, somebody blundered by adding the species name cayenensis to make up the binomial for the yellow yam. Cayenne, the source of the adjective, is and was the principal city of the Guianas. Cayenensis thus implies a South American origin for the plant, which started out in Africa and crossed the Atlantic with the slave trade.

This is a smallish blunder of no real harm to anyone, and less hilarious than the set of blunders that ignorant Europeans caused by mixing up Guiana and Guinea on the west coast of Africa, and then confusing both of them with India, compounding the original blunder that gave India’s name to the Antilles. This is how the native South American rodent Cavia porcellus came to be called Guinea pig in English and cochon d’Inde in French.*

The word “yam” is also of West African origin from Fulani nyami, “to eat”; Twi anyinam “species of yam”) or perhaps, originally, from yet another language of the region. French retained it as igname and Spanish as ñame.

Fufu, which appears in several West African languages (Ewe, Twi, Wolof), as well as in Afro-Cuban Spanish fufú, is the moral equivalent of mashed potatoes. This is not a glib comparison. As soon as African slaves encountered other starchy tubers in the Americas, aroids (dasheen, eddoes) and cassava, they mashed them, too, formed the “dough” into balls, and called the result fufú (as they did and do in some places with the plantains they already knew from Africa).

*By a similar process, the large Mexican fowl Meleagris gallopavo came into English as turkey [fowl] and into French as dinde, a fowl from India, or volaille d’Inde.

†For a fuller discussion of these plants, see under taro.

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