8 



GENERAL BOTANY 



PLANT BODY 



INCOME 



neighbors in the upward growth toward the light. A 

 tree developing in the open always has a more symmetrical 

 form and a fuller leafage than one of the same species growing 

 in a forest. In these and various other ways the environment of 

 any given individual or species of plant is vitally affected by 

 neighboring plants of the same community or society. 



Animals are also factors in the plant's environment in that 

 they tend to injure or destroy plant life for food or for protec- 



tion. Some plants, 

 like the cacti and 

 thistles, are armed 

 and thus protected 

 against the higher 

 forms of animals ; 

 but even these ex- 

 ceptional forms are 

 subject to attack 

 by smaller forms, 

 which may infest 

 the roots or bore 

 into the stem or 

 leaves and either 



1. ENERGY 



2. INORGANIC 

 MATERIALS 



d. OXYGEN 



FIG. 2. Diagram illustrating the nutrition of 

 a green plant 



At the extreme left the income in energy and inorganic 

 materials is shown ; within the circle the main organic 

 substances constructed within the plant body are in- 

 dicated. At the extreme right the outgo in energy and 

 inorganic materials is indicated ; within the circle the 

 energy and waste products of respiration (destructive 

 process) are shown 



kill or injure them. 

 So, while the 

 plant draws upon 

 its inanimate envi- 

 ronment for energy 



and foods, it rmist needs compete, in a hard struggle for its 

 existence, with the other living organisms, including both plants 

 and animals, by which it is surrounded. These living forms 

 constitute its animate environment. 



RELATIONS OF PLANTS TO ANIMALS 



Plants help man and other animals by giving them food 

 and protection and by creating an environment favorable to 

 their needs and comfort. Plants are also of the greatest indus- 

 trial and commercial importance on account of the food, shelter, 



