9 o 



ORGANIC EVOLUTION 



that there are important fundamental resemblances between 

 Solea and the members of the genus Viola. This funda- 

 mental resemblance in the midst of more superficial differ- 

 ences we indicate by classifying both Solea and Viola in 

 a common larger group which we call the family, in this 

 case the violet family or the Violacece. As we have sev- 

 eral genera within the one family Violacea, so we have 



many different families of 

 plants, the daisy family 

 or Composite, the prim- 

 rose family or Primulace&, 

 the rose family or Rosacetz, 

 and so on. Now all these 

 families mentioned have 

 certain general resem- 

 blances to one another, 

 such as the presence of 

 blossoms and seeds. Many 

 other kinds of plants are 

 without either blossoms or 



Flora of the Northern States and Canada, by the cour- Seeds J f CmS and mOSSCS, 

 tesy of the authors and of Charles Scribner's Sons. f ^ example> We distm . 



guish the former as flowering plants or phanerogams, and 

 the latter as flowerless plants or cryptogams. Thus we 

 have different grades in the classification to indicate dif- 

 ferent degrees of resemblance and divergence. 



Moreover, as we study the different groups of plants, we 

 find them very different in the complexity of their organ- 

 ization, in the extent to which their organs and tissues are 

 developed. Some, like the flowering plants, are highly 

 organized, showing very elaborate structure, while others 



