Sweet potato was from the tropic which was taken back to Spain from the Central America and the Northern America in the early days, and spreads to Manila and Malaysia archipelago by Spaniard and Portuguese . In China, a trader whose name was Zhen-Long Chen took the seeds of the sweet potato to China from Luson to Fujian in 1594 (the Ming dynasty). After that, they broadcasted it to Japan and Kagoshima ......etc. via Okinawa.

Sweet potato is not only the most important crops for the animal’s feedstuff but also for the food and the source of the industry in the tropic and the sub-tropic. Its grow area is very wide and broad which includes the 40 S. latitude to 40 N. latitude and even 2,000 meters high. The producing areas are estimated approximately 1500 million acres in the world and the annual producing yields are 130 million tons. In Taiwan, the highest producing area was in 1954 which can achieve 247 million acres and the annual yields were 2.50 million metric tons. After that, it becomes less and less to plant until 1980 which achieved the most lowest point ( about 11,729 tons). Because of the consumer likes to eat Sweet potato, so there are more and more people to plant it so the planting areas are gradually increase to 1.2 million acres in 1996 .

The sweet potato is belongs to the plant of Convolvulaceae whose stem is long, crawls on the ground, but it also has the shape of cluster and middle shape. Leaf blade is heart-shaped and its color is green or purple red. The flower whose color in white to light red is the funnel shape, the root is gradually fat into a root tuber, the sphere shape, the short spindle shape, the long spindle shape and so on, and the color of the skin has white, yellow, brown, red, purplish red and mixed. The flesh is white, yellowish white, yellow or the orange yellow.