A TEXT-BOOK OF GRASSES 
CHAPTER I 
INTRODUCTION 
Economic botany is that branch of the science of 
botany which treats of the uses of plants. All animals, man 
included, are dependent directly or indirectly upon plants 
for their existence. With the exception of water and a 
small amount of mineral matter such as salt, the food- 
supply of all animal life finally may be traced back to 
the constructive metabolism of plants, a process depend- 
ent upon photosynthesis. Many animals derive a whole 
or a part of their food from other animals, but sooner or 
later in the chain of relations between animals and their 
food-supply a point is reached where the ultimate deriva- 
tion is from plants. The vegetable kingdom provides 
directly a large part of the food for man and for his 
domestic animals. It provides the fibers from which much 
of his clothing is made; much of the material for construct- 
ing his home and the articles with which it is furnished; 
many of the drugs, medicines, dyes, condiments, bever- 
ages, and a great variety of other useful articles or 
substances. . 
Of the natural families of plants that contribute their 
quota to supply the wants of man, the grass family exceeds 
all others in the amount and value of its products. To 
A (1) 
