A TEXT-BOOK OF BOTANY 



FOE SECCMSTDABY SCHOOLS 



CHAPTER I 



INTRODUCTION 



1. Occurrence of plants. Plants form the natural cover- 

 ing of the earth's surface. So generally is this true that a 

 land surface without plants seems remarkable. Not only 

 do plants cover the land, but they abound in waters as well, 

 both fresh and salt waters. One of the most noticeable 

 facts in regard to the occurrence of plants is that they do 

 not form a monotonous covering for the earth's surface, 

 but that there are forests in one place, meadows in another, 

 swamp growths in another, etc. In this way the general 

 appearance of vegetation is exceedingly varied, and each 

 appearance tells of certain conditions of living. 



2. Plants as living things. It is very important to 

 begin the study of plants with the knowledge that they are 

 alive and at work. It must not be thought that animals 

 are alive and plants are not. There is a common impression 

 that to be alive means to have the power of locomotion, 

 but this is far from true; and in fact some plants have the 

 power of locomotion and some animals do not. Both plants 

 and animals are living forms, and the laws of living that 

 animals obey must be obeyed also by plants. Of course 

 there are differences in detail, but the general principles 

 of living are the same in all living forms. To begin with the 



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