CORIf OR MAIZE 33 



vary greatly in height. Even in the same field we may 

 find the plants growing in fertile bottom soil several feet 

 taller than those growing on the less fertile soils of the up- 

 land or hillside. The growth is likewise influenced by 

 the amount of sunshine, rainfall, and length of the growing 

 season. Some varieties of corn naturally grow taller than 

 others, even when they are grown side by side. Early 

 maturing varieties are usually smaller than those maturing 

 later. The average height of most varieties is from 8 to 15 

 feet, although some small types, such as pop corn and 

 sweet corn, grow from 4 to 10 feet high, while some other 

 types sometimes reach a height of 20 to 25 feet. 



29. The leaves. — Since corn is a large, rank-growing 

 plant, it needs a great expanse of leaf surface to afford 

 room for the combining of the necessary amount of the 

 elements of plant food required for its growth. Therefore 

 the leaves of the corn plant are much broader and longer 

 than those of the smaller growing cereals. The width 

 of the leaf varies greatly in different types and varieties, 

 and with individual plants of the same variety. Continu- 

 ous selection of seed for a few years from plants having 

 wide leaves has resulted in the production of a wide leafed 

 strain, which is well adapted for forage or for use in the 

 silo. The number of leaves on a growing plant varies 

 from 10 to 20. A leaf grows from each node of the stalk, 

 but the lower leaves seldom grow to maturity, since many 

 are broken off during cultivation, or they wither and die. 

 Usually not more than 12 or 14 are growing at one time. 

 One can scarcely realize what a large surface is exposed 

 by the leaves of a single corn plant. At the Missouri 

 Experiment Station, the exposed surface of twelve growing 

 leaves of a single plant was found to be 24 square feet, 

 from which it may be seen that the total leaf surface 



