112 



SCIENTIFIC AGRICULTURE. 



The hair-like lines sent off from the midrib and nerves are 

 called veins. This distinction is arbitrary, as there is no dif- 

 ference in the structure or function. The various distributions 

 of the veins have received distinctive names, and these are all 

 included under the generic term venation. 



FORMS OF LEAVES. 



Tlieforjns of leaves have also subjected them to an arrange- 

 ment under specific heads. The forms of leaves are said by 

 De Candolle to depend upon the length of the midrib and the 

 relative length of the veins. 



rig. IP. Orbicular leaves are roundish, as in the 



pyrola rotundifolia, or round leaf wintergreen, 

 and nasturtion. Fig. 19. 



Elliptical leaves, as their name Fig. 20. 

 implies, are elliptical or oval in 

 form, as in the whortleberry and 

 wintergreen. Fig. 20. 



Lanceoate leaves are long and tapering at the< 

 point like the blade of a lancet, as in the willow and peach. 

 Fig. 21, a. 



