PART IV— MISCELLANEOUS CROPS 



CHAPTER XXII 

 TUBER AND ROOT FOOD CROPS 



541. Introduction. The principal tuber and root 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 Uttle 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 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 

 HISTORY AND CLASSIFICATION 



542. Origin and History. The common white, or Irish, 

 potato, Solanum tuberosum, is a native of the mountain val- 

 leys of Peru and Chili. Some investigators beUeve that it 

 has been grown m 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 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 

 food, as indicated by the common name 'Irish" potato. It 



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