THE STEM AND THE LEAF 



41 



is neglected, the young corn plants will be overshadowed and 

 dwarfed and the crop greatly injured. But as soon as the 

 cornstalks have lengthened enough to carry the spreading 

 leaves above the tops of ordinary weeds and leave them in 

 the shade, the corn plants are safe from further competition 

 with these plants, though other species that can thrive in weak 

 light may develop later. In the same way wild plants kill off 

 other species by overshadowing them. Under 

 a close thicket of dogwoods ( Cornus), hazels, 



FIG. 26. Stem of "smilax" (Myrsiphyllum) 



I, scale-like leaves; cl, cladophyll, or leaf-like branch, growing in the axil of a 

 leaf; ped, flower stalk, growing in the axil of a leaf 



or buttonbush, hardly any smaller plants can grow, and the 

 most successful competitors with the bushes are such climbers 

 as the cat brier {Smilax, Fig. 49), 1 climbing false buckwheat 

 (Polygonum), wild morning-glory, and climbing hemp weed 

 (Mikania). These support themselves on the bushes or other 

 plants, and secure all the light they need by running along 

 the tops of the supporting plants. 



1 This is not the familiar greenhouse plant shown in Fig. 26, which is 

 usually called smilax by florists. 



