50 The New York State College of Forestry 



outline with pith in the center. The grouping of bundle-scars 

 v.ithin leaf-scars is of decided diagnostic value and constant 

 within the species. The number of bundle-scars may vary from 

 one to thirty or more. Many plants possess three prominent 

 scars. In others the number is larger and they are irregularly 

 scattered, arranged in three groups, in a single lunate line, in 

 the form of an ellipse, etc., within the boundaries of the leaf -scar. 

 r>undle-scars consist of vascular tissue (leaf-traces) which 

 extended from the stem into the leaf and were ruptured and 

 exposed to view at the time of leaf-abscission. 



D. Color of Twigs 



The color of twigs is very variable and caution must be 

 emplo3'ed in using this feature in identification. The colors range 

 from nearly black through shades of green, red and brown, to 

 gray or nearly white. Often the color of a portion of a twig 

 depends upon its exposure. For example, in Basswood the upper 

 part of the twig which is exposed to direct insolation is of a 

 decided reddish cast, while the bark of the lower side is generally 

 olive-green. Subsequently all twigs usually darken with age and 

 eventually assume the hues of the mature bark. Some twigs are 

 dull, others are lustrous or glaucous, that is, provided with a 

 waxy bloom which rubs off. Many are smooth while others are 

 granular, scabrous, or develop corky excrescences or wings, the 

 function of which is uncertain. All grades of hairiness prevail 

 from the pilose type with long, soft hairs, through hirsute, pubes- 

 cent, and tomentose, and are characteristic features of certain 

 species. 



E. Taste and Odor of Twigs 



Supplementing the color characteristics of twigs is that of taste 

 and odor. Cherry twigs have the odor and taste of bitter 

 almonds. The flavor of Sassafras can be detected in the twigs of 

 that species. Black and Yellow Birch contain an ethereal oil of 

 wintergreen odor and taste. Hop-tree and Nannyberry possess 

 twigs which give off a disagreeable odor when broken. The twigs 

 of Silver Maple are distinguished from those of the Red Maple by 

 their rank odor. In employing such characters for identification 

 care must be taken not to include the twigs of Poison Sumach or 

 Poison Oak as they would lead to unfortunate results. 



