HOW PLANTS ARE CLASSIFIED 197 



184. Divisions upon bases other than structure. As already 

 suggested (section 181), plants may be grouped upon the basis 

 of their place of living or mode of life. Also, sub-divisions of 

 the study of plants may be designated by the particular point 

 of view that is kept in mind in pursuing the study. The study 

 of the classification of plants into their proper groups and the 

 determination of their proper generic and specific names is 

 called taxonomy, or systematic botany. When emphasis is placed 

 upon a comparative study of plant organs and then 1 relation- 

 ships, the study is known as plant morphology. Special study 

 of the cell is cytology. Plant activities or work and their rela- 

 tions to the immediate surroundings of the plant are included 

 in physiology, while the relationships of plants to one another 

 and to the environment in general is ecology. One phase of 

 ecology deals with the distribution of plants over the earth 

 and is known as ecological plant geography. The study of plant 

 diseases is known as phytopathology, or plant pathology. A 

 study of the bacteria constitutes bacteriology. A consideration 

 of the useful or harmful aspects of plants is included under 

 the general term economic botany, and under this head there 

 are such Bab-divisions as agricultural botany and horticultural 

 botany. These are but the leading aspects under which plants 

 may be studied. 



It is evident that these divisions have no sharply marked 

 lines between them, and that they are not all made upon the 

 same basis. For example, we might study the bacteria with 

 reference to their structure, which would be morphology ; or 

 in their relation to disease, which would be pathology ; or in 

 their relation to farm and garden crops, which would be 

 economic botany. 



185. Names necessary as labels. In the following chapters 

 we shall study a few representatives of the leading great 

 groups of plants. It is necessary to have specific names for 

 the plants that are used as illustrations of these groups, for 

 sometimes the plants used do not have common names, and 

 sometimes the common names, when used, are applied to two 



