Sweet potatoes are perennial herbaceous vines cultivated in Africa, Oceania, Latin America and Asia for consumption as a starchy food. Despite a common misconception, sweet potatoes (Ipomoea batatas) are not at all related to yams (genus Dioscorea, family Dioscoreaceae). They are handled together here because some countries report the production of sweet potato as yam, and vice versa. And some countries still combine sweet potato and yam in the same category. Sweet potatoes are the most widely grown root crop in developing countries. Although about 40% of the world’s production area is in Africa, the continent only contributes 15% of the world’s sweet potatoes. China produces 80%. Sweet potatoes can play an important part in combating vitamin A deficiency. The crop can grow on marginal lands requiring little inputs. The diet of native tribes of Irian Jaya in Asia is centered around sweet potatoes. In sub-Saharan Africa, sweet potatoes and yams have about the same acreage and in combination they rank 8th in that region. Separately they rank 10th and 12th, respectively. The three dominant producers of sweet potatoes in Africa are Uganda, Nigeria and Tanzania.
In the United States sweet potatoes are often called yams and in Malaysia and Singapore yam is the name given to taro. In West Africa and New Guinea yams are a very important commodity. The tubers can grow up to 5 ft and weigh 150 lbs. Yams are important as food and cash crops and in some countries they have large ceremonial importance. Millions depend on yams in sub-Saharan Africa, mainly in Nigeria, Cote d’Ivoire, Ghana and Benin. Two thirds of sub-Saharan Africa yam production occurs in Nigeria. The rest, save 10%, is in Cote d’Ivoire, Ghana and Benin; the remaining 10% is produced in another 20 countries. Ninety percent of the world’s yam production area is in Western Africa, which produces 93% of the world’s yams.
Reference to numbers/statistics are from FAOSTAT 2010 for the year 2008