36 CORN CROPS 



usually being most numerous on the under side. The 

 above table gives the number estimated for several 

 kinds of leaves.^ 



The stomata also close more or less when the leaves begin 

 to wilt, thus preventing to some extent the loss of moisture. 



24. Chlorophyll-bearing cells. — The work done by the 

 leaf involves the expenditure of energy. There are a large 

 number of cells in the maize leaf filled with minute green 

 bodies, called chlorophyll grains. These not only give the 

 green color, but arrest the energy of the sun's rays, making 

 use of this energy to perform the various activities of the 

 plant. 



25. The flower. — The male, or staminate, flowers are 

 borne in the tassel. The anthers are three in number and 

 filled with pollen. While the pollen sacs are small, about 

 one-fourth inch in length, yet each is estimated to contain 

 2500 pollen grains. 



The female, or pistillate, flowers are borne on the ear 

 and are clo.sely related in structure to the male flowers. 

 When very young, they are borne in pairs, but one is very 

 small and seldom develops. Occasionally both of these 

 grains develop in the tassel flowers of pod corns. Sturte- 

 vant " mentions also an ear of podded flint corn from Ohio, 

 in which the kernels were twinned. These reversions in- 

 dicate that at some time in the early evolution of maize 

 both these flowers functioned, but for some reason only 

 one 110 w develops. 



The principal parts of the pistillate flower are an ovary, 

 or egg cell, a carpel which surrounds this for protection, 

 and a long extension of the carpel,' called the style, or 

 " silk." The details of fertilization are given later. 



' Besbey, C. E. Botany (Briefer Course), p. 45. 

 2 Bul. Torrey Bot. Club, 1894 ■ 336. 



