Reproduction in Flowering Plants 



209 



Bureau of Science, P. I. 



FIG. 125. A mangrove swamp. Note the prop roots which support the trees, 

 and the young plants in the foreground which have dropped from the overhanging 

 branches. 



and pumpkin, in the mature seeds of which the endosperm 

 is lacking. 



A grain of corn is an example of a third kind of seed. In it 

 there is a large endosperm with a small embryo placed at one 

 end of it. The embryo differs from the embryos of the bean 

 and the castor bean in that it has only a single cotyledon, 

 wrapped more or less around the hypocotyl and plumule. 

 In germinating, the hypocotyl grows downward, and the 

 primary root develops from its tip. The plumule grows 

 upward to form the aerial shoot. As in the castor bean, the 

 cotyledon is the absorbing organ through which the foods in 

 the endosperm enter the young plant. 



The flower and embryo in monocots and dicots. In dis- 

 cussing the subject of stems, attention was called to the fact 



