RELATION OF PLANTS TO ENVIRONMENT 13 



Plant breeding, aside from its great practical importance, is 

 of equal theoretical interest to students of evolution and 

 genetics, since the practical breeding of plants is based upon 

 theoretical principles which form the basis for generalizations 

 in these subjects. 



The study of plant diseases, or plant pathology, is also of the 

 greatest practical interest to the growers of all kinds of plants. 

 It has been found that plants are not only subject to diseases 

 produced by such colorless plants as rusts and smuts of grain 

 and tree-killing fungi but that they are also subject to bac- 

 terial diseases, as is the case with man and other animals. To 

 eradicate these diseases and save the great losses produced 

 by them annually, our government has now organized a very 

 large department of plant pathology. It is not necessary to 

 point out in greater detail the importance of plants in nature 

 and the consequent interest and importance attached to the 

 study of plant biology and botany. 



SUMMARY 



1. Plants use the forces of their environment light, heat, and 

 gravity in adjusting their organs properly, in the air and in the 

 soil, for the absorption of raw food materials. 



2. Green plants are unique among living objects in being able 

 to build foods for themselves and for animals out of simple chemical 

 substances which occur in the air and soil. 



3. Green plants are therefore intermediates between inorganic, 

 lifeless nature and the more highly organized animals. 



4. Plants are also important to animals and man in forming a 

 proper environment for their protection and welfare. 



5. Plants are of the greatest importance to man industrially and 

 commercially. 



