BOTANY 



CHAPTER I 

 PRINCIPAL GROUPS OF PLANTS 



INTRODUCTORY 



THERE are four main lines of botanical work now recognized, 

 namely, Morphology, Histology, Physiology, and Ecology. 

 MORPHOLOGY treats of the form and structure of plants and the 

 subject is sometimes divided into (i) external morphology or 

 organography and (2) internal morphology or anatomy (histol- 

 ogy). The former deals with external characters of plant parts and 

 the latter with their minute inner structure. PHYSIOLOGY may be 

 defined as the study which considers life processes and the condi- 

 tions which influence these. ECOLOGY is the study of the adapta- 

 tion of plants and their parts to external conditions. It is impor- 

 tant to bear in mind, however, that these several departments 

 are more or less interdependent, and that one of them cannot be 

 intelligently studied without a consideration of the problems of 

 the others. For instance, as Goebel states, we cannot under- 

 stand the relation of the external forms of organs without refer- 

 ence to their functions. In other words, form and function have 

 a direct relation ; one influences the other. So, too, in the study 

 of ecology we study the influence of external conditions on 

 plants and these, as indicated above, have a direct influence on 

 physiological processes, and thus the study of ecology merges 

 into the study of physiology on the one hand and into morphology 

 on the other. 



While this book will deal chiefly with the structure of plants 

 and their parts, still it will be necessary occasionally to refer to 

 some of the characters of plants which properly belong to other 

 departments of botanical study. 



Basis of Plant Structure. In order to understand the sig- 

 nificance and relation of the various parts of plants it is necessary 



