FROM SEEDLING TO PLANT 



437 



cotyledon re- 

 moved. 



within the seed was made by the plant which bore it, and 

 was stored there for the use of the seed during germination. 

 The chief foods prepared by the parent plant and stored in 

 seeds for the benefit of the growing embryo are : 

 oils, starch, protein, and mineral matter. Some 

 seeds contain all these foods, but most seeds con- 

 tain a conspicuous quantity of only one food. For 

 example, in cotton and flax, and in the seeds of 

 peanuts and Brazil nuts, oil is the principal food ; 

 in corn and wheat, starch is the principal food sub- 

 stance ; in peas and beans, proteins take the lead- 

 ing place. 



From seedling to plant. To observe the develop- 

 ment of the embryo into the seedling, place moist blotting paper 

 in a dish and lay on it some soaked bean seeds. Within a few 

 days the seed coat is pierced by a slender organ which rapidly 

 grows into a root ; finally the seed coat is quite torn, and 

 growing stem and bud force their way out and 

 grow upward. When we watch the bean seed- 

 ling carefully, we see that it develops at the 

 expense of the cotyledons, the seedling becoming 

 larger and stronger as the cotyledons become 

 more and more shriveled. As long as any food 

 remains in the seed the seedling thrives, but 

 when the food supply is exhausted, the seedling 

 droops and dies. If the seedling is to continue 

 its growth, it must be placed in the soil and 

 begin its work of food getting. As soon as the 

 plant is in the soil, its root increases in size 

 and sends off numerous branches which grow and spread 

 farther and farther through the soil (Fig. 305). The stem also 

 grows rapidly, pushes its way upward, and develops numerous 

 leaves. 



FIG. 305. Roots 

 of clover. 



