THE ECONOMIC BIOLOGY OF PLANTS 449 



phorus, sulphur, potassium, calcium, magnesium, and sodium 

 compounds which are so essential to proper rations. (See Chapter 

 37.) They are easily cultivated, ripen quickly, yield largely, and 

 so constitute one of the first and most important crops raised by 

 man. The history of the cereals is the history of the human race, 

 wheat being found imbedded in Egyptian brick five thousand years 

 old. Other grains are found among the relics of the Swiss Lake 

 dwellers, perhaps much older, while the Chinese have cultivated 

 rice for over four thousand years and corn was used in America 

 long before the dawn of history. 



Kinds of Cereals. Wheat is the most important vegetable food 

 in Europe and America. The United States leads in its production 

 with Russia in second place. Not only does it provide the white 

 bread of the world, but macaroni, spaghetti, vermicelli, etc., are 

 also wheat products. 



Rice feeds more people than any other grain, being the chief 

 cereal of China, India, and southern United States and it is esti- 

 mated that one-half the population of the world depends upon it. 



Corn was one of the first cereals to be used by savage tribes be- 

 cause it is easily cultivated in almost any climate; United States 

 also leads in the production of this grain. Not only is it valuable 

 as food for men and animals, as meal, canned or fresh, but starch, 

 corn syrup, glucose, oil, and gluten foods are among its 

 products. 



Oats will thrive in colder climates than any other grain. It is 

 the principal cereal of Scotland, Norway, Sweden, and Iceland, 

 and is used for food and fodder in other temperate regions. 



Barley also endures cold but will thrive in warmer regions as 

 well; it was formerly a valuable food, but is now more used for 

 fodder and for malt to make beer. 



Rye will grow in poorer and rougher soil than any other grain 

 and Russia leads the world in its production. It makes the com- 

 mon " black bread " of Austria, Germany, Russia, and Sweden. 



Buckwheat, despite its name, is not a true grain and while 

 pleasant in flavor, its flour has little food value; it is a native of 

 northern Asia and will grow in poor soil in temperate climates. 



