[Chap. I 



PLANT SCIENCE 



Fig. 5. A mat of moss plants {Hijpnmn) on a decaying log. Several "mushrooms" 

 are also present. Photo by E. S. Thomas, Ohio State Museum. 



called a biologist in the sense that he is a master of the whole field. The 

 facts and principles that have been or may be derived from the study of 

 plants are called botany, and the knowledge similarly gained from the 

 study of animals constitutes zoology. 



Because of the great number and diversity of forms and life relations 

 among both plants and animals, botanists and zoologists have difficulty 

 in viewing their subjects as wholes. Hence most botanists have become 

 especially interested in some one or only a few of the many phases of 

 the subject, such as the classification of plants, their physiology, their 

 structures, life histories, diseases, heredity, geography, or geological his- 

 tory. This specialization of botanists has certain advantages in research 

 and in practice. However, the behavior of plants, in tlie broadest sense, 

 involves the interaction of all these phases of plant life. Hence in the 

 interpretation of plant phenomena botanists are forced to seek an ever- 

 increasing background of biological, physical, and chemical knowledge. 



In a general study of plants we shall be concerned not with the special 

 phases of the subject, but with that general background which experience 



