PHYSIOLOGY OF THE CORN PLANT 



167 



able conditions these lateral roots develop abundantly 

 and rapidly and the root-system of corn is thus profusely 

 branched. 



210. Growth of stems (Fig. 25). All of the nodes in 

 the stem of a corn plant are formed while the plant is quite 

 young. The subse- 

 quent growth or 



elongation of the 

 stem is due to the 

 extension of the in- 



ternodes. Above VM// '%* 2 



each node there is a 

 layer of cells pos- 

 sessing a dark green 

 color and filled with 

 sap. These cells to- 

 gether with the ex- 

 treme tip of the 

 stem constitute the 

 growing points of 

 the corn stalk. As 

 the average corn 

 stem possesses from 

 fifteen to twenty 

 nodes and conse- 

 quently as many growing points, it is enabled to 

 lengthen very rapidly during the growing season. The 

 elongation of the corn stem has been likened to the un- 

 folding of a telescope. The corn stem increases in diameter 

 as a result of the internal accession of cells, rather than by 

 adding layers on the outside. It is therefore an endogenous 

 stem. 



211. Growth of leaves. The author has been able 



FIG. 25. Illustrating development of corn 

 stem: 1, plant about 10 inches high; 2, sec- 

 tion of 1, at base, showing that all nodes, 

 leaves, and tassel are more or less developed 

 at this stage; growth is internodal; 3, full 

 grown stem with leaves removed; 4, cross- 

 section of stem. 



