78 



MASS. EXPERIMENT STATION BULLETIN 159. 



Combined Length and Breadth. 



Very small, 

 Small, . 

 Below medium, 

 Medium, . 

 Above medium. 

 Large, 

 Very large. 



Form refers to the relation of the right and left sides of the leaf. If they 

 lie in approximately the same plane the leaf is said to he flat; if thej^ bend 

 upward the leaf is more or less folded. The midrib may be straight, or if 

 curved backward or downward it is said to be reflexed. The sides of the 

 leaves may be even, or they may be more or less waved when there are not 

 over three "waves," and wrinkled when there are a greater number. 

 When the surface of the blade is more or less irregular it is said to be 

 crumpled. A leaf may present various combinations of these characters. 

 It may be folded, reflexed and even; flat, straight and waved; or it may 

 present other combinations of these characters. Qualifying adverbs indi- 

 cating the degree to which the leaf is folded, waved or reflexed may be 

 freely introduced. The accompanying plates show characteristic leaves 

 from a number of common varieties. These leaf characters have not been 

 widely recognized, but the writer has found them peculiar to the several 

 varieties and extremely useful in identification; in fact, one may recognize 

 many varieties quite positively by them alone. They are most striking 

 from midsummer until near the time of leaf fall. 



The outline of the leaf is usually nearly oval; it may be broad oval or 

 narrow oval. Sometimes it approaches ovale, oblong or roundish. The base 

 includes the proximal one-third of the leaf, and it may be broad, rounded 

 or narrow, while the apex includes the distal one-third excluding the 

 point, and may be broad, medium or narrow. 



There is usually a more or less distinct point which may be small, medium 

 or large, also blunt, acute or acuminate. 



The general color of the normal leaf is always some shade of green, 

 usually light or dark; but may be grayish, bluish or yellowish green. The 

 vein color is frequently tinged with reddish or pinkish red. The position of 

 the leaf is its relation to the shoot on which it is borne, and it may be erect, 

 spreading or drooping, the spreading leaf forming an angle of from 45° to 

 90° with the branch. Next comes thickness, and the leaf blade may be 

 thick, medium or thin. The term "serratures " includes all forms of inden- 

 tation of the margin of the leaf, and their nature may be sharply serrate, 



