Plant Life in General 



trees and shrubs. 



ply the greater part of the energy used in heating and lighting 

 and in running machinery ; and that as friends or foes, cer- 

 tain microscopic plants affect the health and well-being of 

 animals and men. Since plant life is essential to our very 

 existence, we should have a truly vital interest in the science 

 of botany, which has grown out of the accumulated mass of 

 information about plants. 



Botany as a science. A science is a body of classified and 

 systematized facts. The lore of the gardener, the forester, 

 and the casual student of plants may have value, but it be- 

 comes a science only when it has been organized into a system 

 whose principles have been tested and verified by experience, 

 observation, or experiment. Botany is the science that 

 treats of the structures, life histories, physiological processes, 

 distribution, and classification of plants. It is one of the two 

 divisions of biology; zoology, the science of animal life, is 



