PART IV. 



MISCELLANEOUS CROPS 



CHAPTER XXII 

 ROOT AND TUBER FOOD CROPS 



550. Introduction. The principal root and tuber food- 

 crops of the United States are the common Irish or white 

 potato and the sweet potato. The Irish potato, which is 

 used as food and in the manufacture of starch and alcohol, 

 is a tuber, or a thickened underground stem. Several of 

 these are produced on each plant a little below the surface of 

 the ground; they develop from offshoots of the main stem. 

 On the other hand, the portion of the sweet potato which is 

 used as food is a thickened true root. The common or 

 white potato is most largely grown in the North, while the 

 culture of the sweet potato is confined almost entirely to the 

 South. 



THE POTATO 



551. Origin and History. The common white or Irish 

 potato, Solarium tuber osum, is a native of the mountain val- 

 leys of Peru and Chili. Some investigators believe that it 

 has been grown in these countries for two thousand years, 

 but this is merely a supposition. De la Vega found the Peru- 

 vians cultivating potatoes in 1542, and sent some of the tubers 

 to Europe. Several later importations were made into 

 Spain, and from these the growth of potatoes has spread until 

 now practically all of the countries of the world grow this crop 

 to a greater or less extent. The potato was introduced into 

 Ireland in 1586, and soon became an important article of 



