MORPHOLOGY OF LEAVES AND FLOWERS 



593 



Pig. 4451 Kg. 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 Thomfi.) 



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. 445. 



38 



The clinging stem of the Bindweed, showing the alternate leaves. 

 (After ThomS.) 



