V. COLLECTING 



XXII. THE PRESERVING OF PLANTS 



144. More than 100,000 species of flowering 

 plants are known, and it is probable that nearly 

 as many more await discovery. It is evident that 

 if this vast number of facts is to be studied, the 

 facts must be arranged or classified. 



145. If the kinds of plants are to be carefully 

 studied, specimens must be preserved. The plants 

 of an entire region can then be seen, and, what 

 is more important, they can be seen side by side, 

 for comparative study is the only productive method 

 in systematic or descriptive botany. 



146. The plants are preserved by drying them 

 under pressure. These dried and pressed plants 

 are then secured to sheets of large white stiff 

 paper (Fig. 113), and the sheets are filed away 

 in covers, as leaves of music are placed in a port- 

 folio. The covers are laid flat in a cupboard or 

 cabinet. Such a collection of plants is an herba- 

 rium. 



147. Although the specimens shrink some in 

 drying and flowers often lose their color, these 



(110) 



