The Angiosperms or Flowering Plants 



521 



the sperms into it. One sperm unites with the egg, forming the 

 zygote or fertilized egg ; the other unites with the fusion nucleus, 

 forming the endosperm nucleus. 



(polUn grain 



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J^ JLC ^^^-^ OvuXe wall 



^EED 



Fig. 326. The life history of an angiosperm. 



The embryo. The zygote germinates at once and by cell 

 division forms the embryo, which pushes backward into the 

 developing endosperm. The embryo may consist of only a few 

 cells, as in orchids, or it may grow to considerable size, using 

 up the entire contents of the endosperm, the nucellus, and in 

 rare instances, as in the skunk cabbage, even the integuments. 



