366 PRACTICAL BOTANY 



the subsistence of mankind, especially in the cooler parts of 

 Europe. Potatoes are particularly adapted for cultivation as 

 a food crop in regions where the summer is so short and cool 

 that wheat or Indian corn may not mature or produce profit- 

 able crops. Many varieties have been produced by selection 

 of the most promising plants raised from the seed (collected 

 from the berries or "potato balls"). Under the influence of 

 long cultivation the size of the tubers has greatly increased 

 (Fig. 331) and the tendency to bear seed has diminished. 



Our annual potato crop is usually over 200,000,000 bushels. 

 New York is the principal potato-growing state, producing 

 nearly twice as many bushels as any other one of the chief 

 potato-producing states, Pennsylvania, Michigan, or Wisconsin. 



The tomato (^Lycopersicum esculentum) was introduced into 

 cultivation from tropical America, at first as a curious orna- 

 mental plant for the garden, whose fruit was supposed to be 

 poisonous. Its fruit was originally small, two-celled, and wa- 

 tery, but by cultivation and selection has become large, fleshy, 

 and several-celled. It is extensively grown for the market, 

 and in several states large canning establishments handle the 

 product of many special tomato farms. 



Tobacco (Nicotiana Tabacum) was introduced into Europe 

 from America during the latter half of the sixteenth century. 

 The parent form of the cultivated species is said to be found 

 in the wild state in Peru and Ecuador. Tobacco is an ex- 

 tremely profitable though somewhat uncertain crop. It im- 

 poverishes the soil more than any other field crop, since the 

 plant withdraws from it great quantities of nitrates. The 

 annual product of the United States and Porto Rico amounts 

 to over 800,000,000 pounds, the leading tobacco-producing 

 states being Kentucky, North Carolina, and Virginia. 



337. Other important genera. No other plants of the Night- 

 shade family are of great value as food plants, though another 

 species of Solanum, the eggplant, is considerably cultivated. 

 Red peppers ( Capsicum), ground or whole, are much used as 

 a condiment. 



