82 PLANTS AND MAN 



then takes place, resulting in the embryo bursting through its 

 seed coats; the plumule grows upward, above the cotyledons 

 which become green and temporarily make food for the young 

 plant until the true leaves are ready for this task; the radicle 

 penetrates the earth and assumes absorptive functions typical of 

 roots. In a few weeks, the young sporophyte has entirely broken 

 its dependence upon the parent thru the food stored in the cotyle- 

 dons or in the endosperm. It can now carry on all of the main- 

 tenance functions described in the previous chapter. 



In the seed habit, the Angiosperms have achieved a reproduc- 

 tive advance among plants comparable to that found among 

 mammals; in both cases, it has been the exceedingly painstaking 

 care of the embryo which has been an important factor in the 

 attainment of supremacy in their respective kingdoms. 



