106 



GYMNOSPERMS 



cotyledons, and the plumule or apical bud or growing point. 

 These structures are surrounded by the endosperm or food 

 stored within the embryo sac. The embryo sac is enclosed 

 by the remains of the nucellus and the integument becomes 

 modified to form the seed coat or testa, a portion of which 

 grows into a wing-like structure, which makes it possible 

 for the seed to be carried by the wind. All the above struct- 

 ures constitute the seed. 



FIG. 62. White Pine Seed. 1, Outer dark layer of the testa; 2, inner 

 light-colored layer of the testa; 3, endosperm of the stored food; 4, cotyle- 

 dons; 5, plumule; 6, hypocotyl; 7, root; 8, root cap. 



Seed Germination. Under favorable conditions the rudi- 

 mentary parts of the embryo pine continue to develop, 

 finally producing a typical pine tree or sporophyte plant. 



SUMMARY. 



Gametophyte. The male and female gametophytes of the 

 pine are greatly reduced. 



Male Gametophyte. The microsporophylls are arranged 

 in cones, and bear the microspores or pollen grains. The 



