SEEDS AND SEEDLINGS 



33 



certain other special organs that have to do with the making of 

 seeds. One of these organs, when ripened, becomes the fruit. 

 Now, in the embryo of a bean or a peanut or a pumpkin 

 seed, it is very easy to find the parts corresponding to the root 

 and the parts corresponding to the shoot. The two fleshy parts 

 that make up the bulk of the embryo are really special kinds 

 of leaves. If we bend them aside carefully in the embryo of 

 a seed that has been soaked in water, without breaking them 

 off, we can see that they are attached to a short stalklike piece. 

 One end of this rod tapers to a point ; this tip corresponds 



C C 



H 



Fig. 6. Embryos of plants 



/, diagram showing relative positions of the parts of the embryo ; 2, embryo of peanut ; 

 S, embryo of pea; 4, embryo of pine ; C, C, cotyledons; E, epicotyl ; H, hypocotyl 



to the root. The rest of the main stalk, with its outgrowths, 

 corresponds to the shoot. The upper end may be enlarged at 

 the tip into a tiny knob or bud ; in the bean embryo we can 

 make out two little leaves folded neatly over each other. 



The two fleshy leaves are called seed leaves, or cotyledons. 

 The part below the meeting point, sometimes called the radicle, 

 is the hypocotyl, which means " below the cotyledon." The 

 part above is called the first bud, or the plumule, or the epicotyl, 

 which means "above the cotyledon " (Fig. 6). 



Although the cotyledons are considered to be leaves, they do 

 not in all plants become flat and green like the more familiar 

 leaves. In many cases they do not even come above the ground 

 during the young plant's development, as in the pea plant. 



