LEAVES 



165 



veins extend from the midrib to the margin of the leaf are 

 pinnately parallel veined, as in canna ; when the veins originate 

 at the end of the petiole and extend upward and outward to 



FIG. 100. Duration of Leaves. 1, Evergreen, low juniper (Juniperus 

 nand) ; 2, persistent, witch-hazel (Hamamelis virginiand) ; 3, persistent 

 petiole, horse-chestnut (CEsculus hippo castanum) ; 4, branch of linden 

 (Tilia americana) free of deciduous leaves. 



the margin of the leaf, it is palmately parallel veined, as in 

 wild yam. Leaves are reticulate when the veins branch and 

 cohere to form a complete network, as in witch-hazel. Reticu- 



