MAIZE OR INDIAN .CORN 157 



gives the blade elasticity and thus enables it to withstand 

 wind. The blade is supported by the midrib and veins 

 which are merely branches or extensions of the fibro- 

 vascular system previously mentioned in connection with 

 the stem structure. 



The surface of the leaf is covered with a strong epi- 

 dermis, which contains many stomata. These stomata 

 furnish the means by which air passes into and out of the 

 leaf. They are also passage ways for the transpiration of 

 moisture and for the intake of carbon dioxide from the 

 air. 



A microscopic examination of the internal structure of 

 the leaf will reveal a large number of chlorophyll grains. 

 It is to these chlorophyll bodies that the green color of 

 the plant is due. The chief function of the chlorophyll 

 bodies is to arrest and make use of the energy of the sun's 

 rays in performing the various activities of the plant. 



198. The flower. The corn plant bears its stamens 

 and pistils in separate flowers on the same specimen and 

 is therefore monoecious. The staminate flowers are borne 

 in clusters at the top of the plant, forming what is com- 

 monly termed the tassel. The tassel is really a panicle 

 of spikelets, each spikelet bearing two flowers. Each 

 flower has three stamens, which, as they mature, lengthen 

 and thrust the pollen sacs or anthers outside of the flower 

 where they are exposed to the wind. When the anthers 

 are mature they open and liberate the pollen grains. 

 It is estimated that each anther produces about 2500 pol- 

 len grains and that a single tassel produces approximately 

 7500 anthers, resulting in the production of approximately 

 18,750,000 pollen grains to a plant. Investigations as to 

 the relative number of pollen grains to ovaries produced 

 by a corn plant indicate that for every ovary there are 



