CHAPTER IX 

 LEAVES 



141. The Eljn Leaf. Sketch the leafy twig of elm. that is sup- 

 plied to you. 1 



Report on the following points : 



(a) How many rows of leaves ? 



(&) How much overlapping of leaves when the twig is held with 

 the upper sides of the leaves toward you ? Can you suggest a reason 

 for this ? Are the spaces between the edges of the leaves large or 

 small compared with the leaves themselves ? 



Pull off a single leaf and make a very careful sketch of its under 

 surface, about natural size. Label the broad expanded part the Hade, 

 and the stalk by which it is attached to the twig, leaf-stalk or petiole. 



Study the outline of the leaf and answer these questions : 



(a) What is the shape of the leaf taken as a whole ? (See Fig. 

 88.) Is the leaf bilaterally symmetrical, i.e., is there a middle line 

 running through it lengthwise, along which it could be so folded 

 that the two sides would precisely coincide ? 



(6) What is the shape of the tip of the leaf? (See Fig. 89.) 



(c) Shape of the base of the leaf? (See Fig. 90.) 



(d) Outline of the margin of the leaf? (See Fig. 93.) 



Notice that the leaf is traversed lengthwise by a strong midrib 

 and that many so-called veins run from this to the margin. Are 



1 Any elm will answer the purpose. Young strong shoots which extend 

 horizontally are best, since in these leaves are most fully developed and their 

 distribution along the twig appears most clearly. Other good kinds of leaves 

 with which to begin the study, if elm leaves are not available, are those of 

 beech, oak, willow, peach, cherry, apple. Most of , the statements and direc- 

 tions above given would apply to any of the leaves just enumerated. If this 

 chapter is reached too early in the season to admit of suitable material being 

 procured for the study of leaf arrangement, that topic may be omitted until 

 the leaves of forest trees have sufficiently matured. 



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