IDENTIFICATION OF TREES 189 



indistinct, as is frequently the case, they may be revealed 

 if a thin slice is taken off the surface of the leaf-scar. 

 This surface section must be very thin, however, since 

 the number of bundle-scars exposed by a deep cut is 

 often different from that on the surface, and this latter 

 number is the one used in the keys and descriptions. A 

 distinction is made between a group in which the 

 bundle-scars form a single line and a second group in 

 which they are variously scattered and grouped or in 

 a double line. 



Buds — In regard to their position buds are ter- 

 — 5X minal or lateral. Buds produced at or near the nodes 

 but not in the axil of a leaf-scar are called accessory 

 buds. Of these there are two kinds: Superposed buds 

 located above the axillary buds and collateral buds 

 located at either side of the axillary buds. The former 

 are shown in the Butternut (fig. 101) and the latter in 

 the Red Maple (fig. 102). Classified according to what 

 they produce there are flower buds which contain the 

 rudiments of flowers, leaf buds which contain rudiments 

 of leaves, and mixed buds which produce both flowers 

 and leaves. Flower buds are generally stouter than leaf 

 buds. 

 -? Most species by the end of the growing season have 

 o-fcaroiTna^-^^^"^^^ terminal buds which remain through the winter 

 sx— supuie ^^^ ^^® destined to continue the growth the following 

 p_star-^^^' spi'i^g- I^ some species, however, such as the Mulberry 

 shaped Pith(fig, 103)the terminal bud together with the tip of the 

 twig dies away and drops off before the beginning of winter 

 leaving a small scar at the end of the twig. The presence or 

 absence of the terminal bud is a very valuable point of distinction 

 and is used throughout in the keys. Unfortunately it is not always 

 possible at a cursory glance to say whether the terminal bud is 

 present or absent and a hand-lens must generally be used for an 

 accurate determination of this point. In the Mulberry figured, 

 the self-pruning scar formed by the dropping off of the terminal 

 bud is perched on the tip of the twig with the topmost lateral bud 

 obviously in the axil of the last leaf -scar. Frequently, however,. 



