HO W PLANTS ARE NAMED. 157 



has had the best training and the longest 

 experience, is the best fitted to make such 

 judgments. He knows that violets which 

 are widely different in general appearance 

 may be only extreme forms of one species. 

 If the difference lies in the color, he gives 

 it little attention, for he knows that color 

 varies in all plants. If the difference lies in 

 the shapes of the leaves, he gives it more at- 

 tention, still does not rely upon it, unless the 

 leaves are wholly and essentially unlike be- 

 tween the one and the other. Here again it 

 is a matter of judgment as to what consti- 

 tutes this essential difference. The common 

 hooded violet ordinarily has large heart- 

 shaped leaves, still they occasionally vary so 

 as to resemble the much-cut leaves of the 

 bird's-foot violet. A difference in the shapes 

 of the parts of the flower is of more conse- 

 quence. The general habit and appearance 

 of the plant are important. If, after consid- 

 erable thought and study, the botanist satis- 

 fies himself that the violet is a new species 

 to his region, that it is not a form of any of 

 the species described in his botany, then his 

 trouble has just begun. It is not enough 

 that the plant be new to his region : it is not 

 new if there is another violet like it in the 



