HOW TO DISTINGUISH TREES 239 



leaflets ; that they stand singly, not in pairs ; and that 

 they are lobed, each lobe with one or two sharp points. 

 Examining the twig of an elm, we find that the leaves 

 are also simple, and alternate, but that they are finely 

 toothed. On this sprig of maple the leaves are in pairs, 

 they stand opposite, and are both lobed and toothed. On 

 the ash we find each leaf made up of several leaflets ; it 

 is a compound leaf, and we find the leaves opposite or in 

 pairs, while in the hickory the leaves are also compound 

 but not in pairs. 



Thus, the leaves are an excellent guide to the study of 

 trees ; and since opposite leaves also leave opposite scars 

 and lead to opposite buds and branches, they help us to 

 know the trees even in their winter garb. 



We will arrange our common forest trees according to 

 their leaves, and thus make a key which will help us to 

 recognize them with more certainty. Generally we shall 

 be assisted by the fruit, the twigs, the bark, and the buds ; 

 more rarely by the flowers, since these can be seen only 

 during a few days in each year, and in some cases are 

 even then quite difficult to examine. 



Looking over our trees, we may at once divide them 

 into two large groups : the evergreen or cone-bearing trees, 

 and the broad-leaved or deciduous trees. These names 

 we must not take too strictly, for some evergreens like 

 the tamarack shed their leaves every fall, and some 

 deciduous trees like live oaks are green the year round. 



