yjjj PREFACE. 



world is filled with untold billions of leaves, no two 

 of which are exactly alike. 



This is a case in point where Nature distinctly 

 shows that infinity of character which sometimes 

 balks all attempts at a rigid classification. I am still 

 of the opinion that types and rules are valuable only 

 as guide-posts are on a strange path. The drawings 

 and descriptions set forth in this volume, which pro- 

 ceeded from original investigation with an attempt 

 to give a different point of view from that of the 

 professional botanist, remain as good to-day as they 

 were when the book first appeared. But meantime 

 the characteristic unrest of the scientific mind has 

 produced important changes in both nomenclature 

 and classification. The International Congress of 

 Botanists, held at Vienna, June, 1905, established 

 a code which now meets with universal acceptation 

 leastwise among all generous and broad-minded 

 botanists. 



These recent changes involve more than the super- 

 ficial naming of plants : they mean that a plant or a 

 tree is at last placed where it belongs relatively with 

 some other plant or tree. To be sure, botanical re- 

 search is ever going on, new species are constantly 

 turning up, and old ones are proving to have been 

 insufficiently studied. One is not disposed to com- 



