n8 



WEEDS OF THE FARM AND GARDEN 



plants, as the grape, grow until killed by frost, whatever 

 buds are not fully developed at that time being killed. 

 This is known as indefinite growth. 



Leaves. Leaves are 

 borne on stems at the nodes. 

 They are usually expanded 

 and are nearly always for the 

 purpose of making plant 

 food. In some cases they 

 store food, as in the leaf of 

 the century plant; the bud 

 scales of the hickory are 

 Fig. 40. Cross section of an modified leaves, the small 



endogenous stem of corn (Zea 

 Mays). S, node; A, sheath of 

 leaf. The small dots, the fibro- 

 vascular bundles. (C. M. King.) 



scales on the rootstock of quack 

 grass are also modified leaves. 



A typical leaf consists of a 

 blade, the stalk or petiole, and a 

 pair of stipules. In some cases 

 the stalk may be wanting and the 

 leaf is said to be sessile, in others 

 the stipule is wanting and in a 

 few the blade is wanting. 



The blade is the expanded part 

 of the leaf and is for the purpose 

 of making food. The petiole is 

 the stalk and serves to fix it to the 

 stem. The stipules are a pair of 

 small scales at the base. There 

 is great variation of the different 



parts of the leaf. 



rr,, i j < i Fig. 41. R, R, tendrils of 



There are two kinds of leaves j ap a n j e ivy, modified 



as to venation. Corn and other stem. 



