20 THE BOOK OF WHEAT 



formation of starch is yet quite a mystery. Its accumulation 

 in the leaves cannot be detected in wheat as it can be in a 

 large number of other species. Neither are reserves of sac- 

 charine matters to be found there. It is not until the last 

 stage of vegetation that starch is formed. Consequently cli- 

 matic influences at the close of the growing period have a 

 marked effect on the amount of starch produced, and cause it 

 to vary greatly from year to year. 



The process of transporting elaborated material begins in 

 the planted seed, and does not cease until the wheat is dead 

 ripe. This is the explanation of wheat ripening after it is 

 cut. It also explains the fact that wheat straw, as well as 

 many other straws, is not as well liked by animals, and is not 

 as nutritious, after it is ripe as when green, or when cut before 

 ripe. 



Fertilization. The one-seeded ovulary is a little greenish 

 swelling. It is surmounted by the stigmas, two erect and ad- 

 jacent aigrettes of plumes. There are three stamens, and the 

 anthers are compactly arranged about the ovulary. At flower- 

 ing the filaments to which the anthers are attached elongate 

 rapidly. As the anthers are pushed upward, they suddenly 

 overturn, and the pollen falls upon the stigmas, which have 



4-40A.M A-43A.M. 4-45 A.M. 4-17 A.M. 4-55AK S-^OaAJ* 5-15 A.M 5-13 A.M 



THE OPENING OF THE FLOWERS OF WHEAT. (AFTER HAYS) 



now grow slightly divergent. These delicate operations all 

 take place within the closed flower and generally wheat is thus 

 essentially self-fertilized. The anthers are now pushed out- 

 side of the glumes, and the wheat is popularly said to be in 

 flower. As soon as the pollen comes in contact with the 

 stigmas, it germinates by sending out a long tube (called the 

 pollinic branch) into the ovulary. This completes fertilization 

 and the grain is formed. If fertilization in incomplete, the 

 ovularies remain unfertilized, and the spikes bear sterile flowers 

 in which no kernels are formed. It seems that the crop is thus 



