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THE AMERICAN NATURALIST 



[Vol. L 



by a study of the indigenous endemic genera, is composed 

 almost entirely of plants which are herbaceous in habit. 



2. Herbs tend to be grouped in fewer and larger genera 

 and families than woody plants. 



3. It is therefore concluded that herbaceous plants, pre- 

 sumably because of the brevity of their life cycle and the 

 rapid multiplication of generations consequent thereto, 

 are in most cases undergoing evolutionary development 

 much more rapidly than are trees and shrubs. 



4. From this conclusion are drawn inferences as to the 

 origin of the herbaceous habit and the antiquity of the 

 Angiosperms. 



