IDENTIFICATION OF TREES 193 



the Ash are not covered by persistent bases of leaf-stalks and there 

 are 2 or more pairs of scales to the leaf buds, we therefore pass 

 to 14. The relatively small size of the buds and their freedom 

 from stickiness takes us to 15 where the number of the bundle- 

 scars and the other characters given show us that we have in hand 

 a twig of one of the Ashes. We now turn to N"o. 165 and confirm 

 our determination of the genus by reading the general description 

 of the Ashes. To find out which Ash we are dealing with we 

 procede with the key of the Ashes and, knowing that the leaf-scars 

 in our specimens are deeply concave on their upper margins, we 

 conclude that we have the White Ash {Fraxinus americana). 

 At page 422 we find a detailed description with photographic 

 illustrations of this species and may learn the winter characters 

 of the tree not already given in the key. If the description and 

 photographs do not correspond to the tree under investigation, we 

 know that we have gone astray at some point in the key, and 

 turning back we repeat the analysis taking if need be the other 

 alternative of a pair where the choice had been doubtful. 



The meaning of unfamiliar terms may generally be found in the 

 glossary. Often, however, the photograph offers a better explana- 

 tion. Thus in distinguishing the Carolina from the Lombardy 

 Poplar, the word "spire-shaped" as applied to the habit, can best 

 be understood by reference to the picture of the latter species. 

 "WTien a choice within a number seems impossible from the infor- 

 mation available, trial should be made of both contrasting para- 

 graphs. In the key to the Oaks, for example, the character of 

 the bark — whether flaky or not flaky — is used as a distinguishing 

 mark. AYith only the twig at hand, it may still be possible to trace 

 the name by trying the tree first under "bark flaky" and if this 

 does not lead to the correct name, then under "bark not flaky." 

 It might seem needless to suggest that both the contrasted parts 

 of each number encountered should be read but work with students 

 has shown that such a suggestion may be useful. 



Sometimes a tree is variable in the characters used m the key. 

 Thus the Chestnut has terminal buds sometimes present on the twigs 

 though they are generally absent. In such cases, however, and 

 where there is a legitimate doubt as to whether the tree should be 

 placed in the first or the second group, it has generally been placed 

 in both so that either of the two choices should lead to the correct 



