CHAPTER XX 

 SOME USEFUL PLANTS AND PLANT PRODUCTS 



332. Cereal Grains. Much has been said in previous 

 pages (see especially Chapter XIII) of the cereal grains 

 wheat, Indian corn, rye, oats, barley, rice, and millet. All 

 the cereals supply food to a greater or less extent both for 

 man and for domestic animals. Food for man is obtained 

 from the fruit of the plant (the kernel or grain), in the form 

 of flour or meal, the extracted starch, and a great variety of 

 " cereal foods " or " breakfast foods " ; domestic animals eat 

 the kernels (especially of oats and corn), and also the leaves 

 and stalks the latter in the form of straw or " fodder." 

 As a group the cereal grains are by far the most important 

 source of food, and the progress of civilization has been in 

 large measure dependent upon the increase of the areas 

 within which they are cultivated. Of this group of plants, 

 wheat is most valuable because it contains the best propor- 

 tions of different food substances especially starch and 

 proteins. In most parts of the world that are occupied by the 

 white race, wheat is the chief vegetable food. Rice, however, 

 which contains a larger proportion of starch than any of the 

 other cereals, is actually depended upon by a larger number of 

 people than is wheat. Rice is said to be the principal food of 

 from one-third to one-half the population of the earth. Rye 

 largely takes the place of wheat in the colder or less fertile 

 regions of Europe. Oats are used most widely as food for 

 horses, and barley is most important as a source of malt for 

 the brewing of beer. Millet is used chiefly as food for ani- 

 mals, although it is used as food for man also in some parts 

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