A well-traveled root: A vendor sells sweet potatoes at a market near Manila in 2011. The Portuguese brought the root to the Philippines all the way from the Caribbean. Ted Aljibe/AFP/Getty Images hide caption

itoggle caption Ted Aljibe/AFP/Getty Images

Sweet potato evangelist Maria Isabel Andrade from the International Potato Center drives around Mozambique in her orange Toyota Land Cruiser. Dan Charles/NPR hide caption

itoggle caption Dan Charles/NPR