vi PREFACE 



the case with street trees, park trees, and cultivated 

 trees in general. If fruit characters are needed for 

 identification and no fruit can be found on the 

 tree, search the ground directly beneath for old 

 fruits. If any are found, they may usually be re- 

 garded as having dropped from the tree, unless the 

 fruit is easily blown by the wind, or the ground is 

 sloping and other trees grow higher up the slope 

 where fruits might easily roll down. 



In using the key begin with No. i and read the 

 two lines preceded by this number, deciding which 

 one of the two applies to the tree under considera- 

 tion. If the leaves of our tree are more than | of 

 an inch long, as most leaves are, we next pass to 

 No. 2, as indicated by the figure 2 following this 

 line, and read the two lines preceded by the figure 2, 

 deciding which one of these two applies to our tree, 

 and again passing to the number indicated after 

 the proper line. This simple process is repeated 

 until we reach one or more common names in full 

 faced type. If a number is found after this name 

 (as in No. 6) it means that the name is that of a 

 genus including two or more species. In order to 

 decide which species of the genus we have, we pass 

 to the number indicated and proceed as before. 

 To illustrate this, suppose we reach No. 6, in the 

 key, deciding that we have a Pine, we next turn 

 to No. 76 in order to find which Pine we have, by 



