STUDY OF A FAMILIAR PLANT 3 



as well as a short part of the very base of the stem. Before 

 the young root has grown very far, branch roots begin to grow 

 from it (Fig. 2, B). At this time we can see that the seed 

 leaves and the part of the radicle still within the seed coat 

 are also swelling, and that just within the edge of the splitting 

 seed coat there is a flat projection (a peg) which has grown 

 out of one side of the radicle. Now the upper portion of the 



C ' D 



FIG. 2. A, a germinating squash seed; B, C, and D, stages in the 

 development of the seedling. Notice how the "peg" and the lengthening 

 upper part of the radicle help to free the seed leaves from the seed coat. 



radicle grows still more and bends so as to push out of the 

 seed. This lengthening of the radicle finally pulls the seed 

 leaves out of the seed coat, the latter being held firmly in 

 place by the peg (Fig. 2, C). The seed coat has now been 

 thrown off entirely, and the radicle straightens so that the 

 end bearing the seed leaves and the plumule is turned upward. 

 3. Growth of the Seedling. The young plant just be- 

 ginning to grow is called a seedling. When the growth of the 

 radicle has pushed the seed leaves well above the surface 

 of the soil, they spread apart, grow, and become green like 

 ordinary leaves (Fig. 2, D), although they are different in 



