Ipomoea batatas, Lam.
The sweet potato is somewhat misnamed, as it is not related to the potato (solanum tuberosum), and, in fact, share little in common with them at all. Sweet potatoes are members of the morning glory (Convolvulaceae) family, whereas potatoes are members of the Belladonna (Solanaceae) family along with tomatoes, red peppers and eggplant (CGIAR). Additionally, the sweet potato is a storage root rather than a tuber like the potato.
However, like the potato, sweet potatoes have proven to be a very productive and nutritious crop. They have been incorporated into the cuisines of many different cultures around the world, and have adapted to a variety of environments.
The origins of the sweet potato are difficult to define. Most evidence points to the region around Columbia, Venezuela and Panama as the most likely point of domestication, but researchers are divided as to what specific area was their original home. This difficulty is compounded by the lack of obvious wild progenitors of the plant. While there are many related species in the area, none possess the enlarged root that is characteristic of the sweet potato. The consensus is that Ipomoea trifida is the most closely related wild species, and this is supported by anecdotal evidence that it occasionally forms a similar enlarged root in high altitudes (O'Brien).
It is clear, however, that the sweet potato has been an important food crop throughout South and Central America for a long time. Archaeological evidence shows that it was in cultivation by at least 5000 years ago, but one site which dates to before 8000 BCE suggests that it may be one of the earliest cultivated plants in the world (O'Brien). It then went on to become an important food crop to many South and Central American cultures including the Inca empire.
There were two major dispersions of the sweet potato out of South America, the first of which appears to have occurred prior to the arrival of the Spanish. The exact means for this dispersion are disputed, but the sweet potato was in cultivation in the Polynesian islands all the way to New Zealand prior to European influence. There is a great deal of evidence for this throughout the pacific islands including the presence of many different varieties of the root on the islands, as well as the discovery of sweet potato roots in archaeological sites which predate European contact. Many believe that the pre-Columbian presence of the sweet potato in the Pacific Islands suggests that there was contact between them and the South American mainland. Thor Heyerdahl cites this as part of the justification for his Kon-Tiki voyage (Heyerdahl, 102). Others have pointed out that other agents could have transferred the plant to the islands including birds or transportation of the seeds by sea. These would explain the lack of transference of other useful products such as maize and manioc that would probably have taken place had there been extended contact between the peoples of the two regions (O'Brien).
The second major distribution of the sweet potato was the result of European contact in the Americas. Here they were introduced to almost every part of the world including Europe, China, India, Japan, Southeast Asia, and Africa. They were quickly incorporated into the various cuisines of these regions and adapted to the varying environments. Currently the majority of sweet potatoes in the world are grown in China and Southeast Asia, and developing countries account for 95% of the world's sweet potato production.
Sweet potatoes are very nutritious and versatile crop which have been incorporated into the livelihoods of many different cultures. The enlarged roots can be baked, boiled, or fried, and incorporated into a variety of dishes or eaten by themselves. They are a good source of carbohydrates and high in vitamins A and C. The leaves can also be eaten to provide extra protein and vitamins and minerals. Resources
http://www.cipotato.org/sweetpotato/
“CGIAR: Research & Impact: Areas of Research: Sweet Potato.” 11 Nov 2008 http://www.cgiar.org/impact/research/sweetpotato.html. O'Brien, Patricia J. “Sweet Potatoes and Yams.” The Cambridge World History of Food. Cambridge: Cambridge University Press, 2000. “Sweet potato, raw, unprepared.” USDA National Nutrient Database for Standard Reference 2008. 7 Nov 2008 http://www.nal.usda.gov/fnic/foodcomp/cgi-bin/list_nut_edit.pl.