VI 



INTRODUCTION 



As I have already said in another book, 1 one of the most interesting ways 

 to know a tree is to be able to recognize it at a distance by its general outline. It 

 is surprising how easy such recognition becomes to one who looks for the distinguish- 

 ing characters of tree growth. Many trees may be known almost as far as they 

 can be seen, and it is a real pleasure to name them when one goes swiftly by in 



THE INTERMINGLING BRANCHES OF THE SWAMP WHITE-OAK 



trolley, train, or automobile, or to pick them out from afar when enjoying a ramble 

 over the highway. 



There are two distinctive types of tree outlines, due to the two ways in which 

 the main trunk develops. In some trees it grows straight up, sending out branches 

 along its sides but continuing clear to the top. Such a tree represents the excurrent 

 mode of growth : the pin oak and the balsam poplar are good examples. In other 

 trees the main trunk divides into several large branches to make an open vase-like 

 form. These represent the deliquescent mode of growth : the American elm and the 



1 "Seeing Nature First." J. B. Lippincott Company, Philadelphia. 



