PARTS OF SEEDS: THE PINE 15 



and extend in a nearly horizontal direction, and the branching 

 of these finally results in a great mass of fibrous roots radiating 

 in all directions in the upper soil layers. About the same time 

 or very soon after the root emerges, the conical fold of the leaves 

 emerges from the other end of the groove. This conical form of 

 the folded leaves wedges its way directly upward through the soil. 

 The leaves elongate and unfold. 



THE PINE. 



19. The pine seed. The seeds of the pine are formed on 

 the upper (inner) surface of the scales of the pine cone (see 

 paragraph 544 on cones of the pine). The seeds are oval and 

 somewhat compressed and flattened, and attached to the lower 

 end of the scale, two on each scale. As they become freed from 



sc 



Fig. 21. 



Pine seed, section of. sc, seed 

 coat; w, remains of nucellus; end. 

 endosperm ( = female gameto- 

 phyte); emb. embryo = young 

 sporophyte. Seed coat and nucellus 

 = remains of old sporophyte. 



Fig. 22. 



Embryo of white 

 pine removed from 

 seed, showing sev- 

 eral cotyledons. 



Fig. 23. 



Pine seedling just emerg- 

 ing from the ground. 



the scale a long, thin and broad strip of the scale splits off and 

 remains attached to the seed as a wing. A section of the seed 

 shows the thin papery remnant of the nucellus (see footnote, p. 9) 

 lying between the seed coats and the white mass of the endo- 

 sperm. Within this lies the embryo. The root and stem 

 together form a straight cylindrical portion, and at the stem end 

 there is a crown of small needle-like leaves, the seed leaves or 

 cotyledons (see fig. 22). The cotyledons are numerous in the 

 pines. The embryo is entirely destitute of chlorophyll, but 

 during germination, even if the seedlings are grown in the dark 



