WHEAT. 105 



the greater part is raised in the Mississippi Valley. 

 The progress of wheat-growing is steadily westward. 



In 1849 the central line of production passed 

 through Eastern Ohio; in 1859, through Eastern 

 Indiana; in 1869, through Eastern Illinois; in 1879, 

 through Central Illinois, and in 1889, the central line 

 was on the western side of the Mississippi river. In 

 1849 only three per cent of the wheat was produced 

 west of the Mississippi river. The fortieth parallel 

 nearly divides the crop into northern and southern 

 halves. 



Wheat production has been stimulated by three 

 prominent causes: 1. The possession of large areas of 

 fresh lands, easily brought into cultivation; 2. The 

 extension of railway construction, and 3. A period of 

 several years of poor crops in Western Europe. The 

 first cause is fast disappearing, and the second is be- 

 coming less important. The third is as uncertain as 

 the seasons. 



Structure. — The wheat plant belongs to that class 

 of plants in which the first leaves of the embryo are 

 alternate, technically known as monocotyledons. The 

 family to which it belongs is characterized by having 

 hollow stems with closed joints, alternate leaves with 

 their sheathes split open on the side opposite the blade. 



The flower of the wheat has three stamens, the 

 anthers, which contain the pollen or fertilizing ele- 

 ment, being suspended on thread like filaments. The 

 stigma, which receives the pollen and conveys it to the 

 ovary, or female element, is in two parts and is 

 feathery. It is necessary for the ovary to be fertilized 

 with the pollen before any seeds can be formed. It 

 is believed that it is better for the ovary of a given 



