PARTS OF SEEDS: THE BEAN 



and arches up in the form of a loop. It is this loop which breaks 

 the way through the soil, since it would be a difficult task for 



Fig. 4. 

 Bean seeds germinating, seed coat slipping off. 



Fig. 5. 



Beans germinating, one cotyledon removed, 

 showing expanding plumule. 



the slender stem to push the bulky cotyledons up ahead of it. 



The cotyledons are therefore 



pulled from the ground as 



the loop straightens up after 



emerging from the soil. This 



portion of the stem (hypo- 



cotyl) becomes quite long in 



the bean, but is quite short 



in the corn. The cotyledons 



are thus lifted above the 



ground. They become more 



or less shrivelled and shrunken Fi s- 6 - 



, .. How the garden bean comes out of the ground. 



because 01 the food SUDStance First the looped hypocotyl, then the cotyledons 



pulled out, next casting off the seed coat, last the 



Withdrawn tor the growth Of plant erect, bearing thick cotyledons, the expand- 

 ing leaves, and the plumule between them. 



the seedling, and finally fall 



away, as the young membranous leaves expand and the stem 



elongates. 



