26 COMPARATIVE STUDY OF CEREALS 



plants as crossed seeds, and continued self-fertilization will result in 

 dwarf plants with very low productivity. It is entirely different with 

 barley, wheat, and oats, as they are self-fertilized with no ill effect 

 and apparently are not benefited by crossing. 



Formation of the Seed. When the contents of the pollen grain 

 pass down into the ovary they unite with the egg-cell in the ovary. 

 Growth in the ovary begins at once. One part of the egg develops 

 into a young plant or embryo, while another portion develops into a 

 storehouse of food for the young plant and is called the endosperm. 



Fia. 13. Diagram of a corn kernel to show the four principal parts, namely, hull, aleurone 

 layer, endosperm or starchy portion, and germ. 



The whole is called a seed, as wheat or barley grains. The wheat 

 grain is covered with a seed-coat, which is only the remnant of the old 

 ovary after the young plant and its storehouse have developed inside. 

 In milling, the seed-coat is taken off as bran. 



Composition of the Seed. The seeds of grasses are said to be 

 starchy, consisting in general of 75 to 85 per cent starch (Fig. 13). 

 The grain, however, can be divided into four parts (1) seed-coat, 

 (2) aleurone layer, (3) endosperm, (4) germ each very different 

 in composition, and the proportion of these parts affects the composi- 

 tion of the whole grain. 



