Nature Bulletin No. 169-A   November 14, 1964
Forest Preserve District of Cook County
Seymour Simon, President
Roberts Mann, Conservation Editor

****:THE SWEET POTATO

When the Spanish explorers first came to the New World they were 
searching for an ocean route to India and its fabled treasures of gold, 
silver, spices and jewels. They found them on these two new 
continents, North and South America, but they found many other 
things far more valuable, including three of the world' s most 
important food plants: corn, the white or Irish potato, and the sweet 
potato.

Being a tropical plant, the sweet potato probably was found before the 
Irish potato -- by Columbus in the West Indies, by Balboa in Central 
America, and by Pizarro in Peru. Like corn, it was not found growing 
wild, but it had been cultivated by the Incan and pre-Incan races for 
thousands of years. They had developed many varieties, as is shown by 
their ancient pottery. In most places in Latin America, the sweet 
potato is called "camote", but the Incans called it "batata" and that is 
apparently the origin of our word "potato".

The sweet potato was carried back to Spain and thence to Italy, from 
where it spread to Austria, Germany, Belgium and England before the 
first Irish potatoes arrived. It took 200 years for the English to accept 
Irish potatoes as being fit for human food, but the sweet potato 
immediately became a rare and expensive delicacy. Now it is widely 
grown in Asiatic lands, including Japan and southern Russia, in the 
warmer Pacific islands, in tropical America, and in the United States 
as far north as New Jersey.

Outside of the tropics, sweet potatoes thrive only in the warmer 
temperate climates, and do best in a loose sandy soil that is well 
drained. They produce seed only in the tropical climates. In northern 
climates, new plants are obtained by planting roots, or cuttings of the 
vines, in beds. The sprouts that form are pulled and transplanted to 
fields one sprout to a "hill". Once well started, they require little 
moisture and, unless attacked by the numerous diseases and insect 
pests to which they are subject, develop many potatoes in each hill.

Sweet potatoes produce more pounds of food per acre than any other 
cultivated plant, including corn and the Irish potato. More nourishing 
than Irish potatoes because they contain more sugars and fats, they are 
a universal food in tropical America, and in our southern states where 
they are baked, candied, boiled and even fried. Vast quantities are 
canned for consumption in the United States. Of the 200 or more 
varieties there are two main types. The "Jersey" and related varieties 
having dry mealy flesh are favored in the northern states. The other 
type, more watery but richer in sugar and more soft and gelatinous 
when cooked, is favored in our southern states where they are called 
"yams". The true yam, however, originated in China and is a different 
plant related to the lilies. The Irish potato, believe it or not, belongs to 
the Nighshade Family.

The sweet potato botanicaly, belongs to the Morning Glory family. 
There is another member of this family, a native weed known in 
Illinois and Indiana as "wild potato vine", "wild sweet potato" or 
"man-of-the-earth", with an enormous fleshy root much esteemed as 
food by the Indians. Above ground, the sweet potato develops creeping 
twining vines with pink or purple blossoms like those of the morning 
glory. Its thick starchy roots develop into the tubers we call "sweet 
potatoes". These contain carotene, the chemical which produces the 
orange colors in autumn leaves and in carrots. The Indians in Latin 
America make a beautiful permanent red dye from the mixed juices of 
limes and sweet potatoes.

Said the sweet potato to the Irish potato: "You're no potato! I yam. "