100 



ESSENTIALS OF BOTANY 



Compare the mode of veinmg or venation of the elm and the 

 maple leaf by making a diagram of each. 



These leaves agree in being netted-veined, i.e., in having veinlets 

 that join each other at many angles, so as to form a sort of delicate 

 lace-work, like Figs. 59 and 60. 



They differ, however, in the arrange- 

 ment of the principal veins. Such a leaf 

 as that of the elm is said to be feather- 

 veined, or pinnately veined. 



The maple leaf, or any leaf with closely 

 similar venation, is said to be palmately 

 veined. Describe the difference between 

 the two plans of venation. 



117. Relation of Venation to 

 Shape of Leaves. — As soon as the 

 student begins 

 to observe leaves 

 somewrhat 

 widely, he can 

 hardly fail to 

 notice that there 

 is a general rela- 

 tion between the 



plan of venation and the shape of the 



leaf. How may this relation be stated? 



In most cases the principal veins follow 



at the outset a pretty straight course, a 



fact for which the student ought to be 



able to give a reason after he has per- 

 formed Exp. XVI. 



On the whole, the arrangement of the 



, , , , i-j!c Apple, with Stipules, 



veins seems to be such as to stiiien 



the leaf most in the pai;ts that need most support, and to 



reach the region near the margin by as short a- course as 



Fig. 62. Palmately Divided 

 Leaf of Buttercup. 



Fir,. 



Leaf of 



