MORPHOLOGY OF LEAVES AND FLOWERS 



593 



Pig. 4451 Pig. 445II 



Fig. 445. I. "Vetch. (Lathyrus aphaca) , showing opposite leaves; r, tendril; b, 



flower ; f, fruit. Stipules performing the function of leaves. 



II. Grass type of leaf ; L, leaf blade ; G, leaf sheath ; Lig, ligule. 



(After Thome.) 



Leaves are usually arranged so as to secure the best exposure to 

 the light. In the milkweed there is a pair of leaves at each node 

 and the two leaves are on opposite sides of the stem. Here the 

 leaves are said to be opposite. 



Fig. 4 46. The clinging stem of the Bindweed, showing the alternate leaves. 



(After Thome.) 

 38 



