G YMNOSPERMS. 



I89 



by currents of air, the split suddenly opens, and a cloud of 



pollen bursts out from the numerous anther 



locules. The pollen is thus borne on the 



wind and some of it falls on the female 



flowers. 



311. Form of the mature female cone. — 

 A cluster of the white-pine cones is 

 shown in fig. 163. These are 



mature, and 



the scales have 



Fig-. 163. 

 White pine, branch with cluster of 

 mature cones shedding the seed. A 

 few young cones four months old 

 are shown on branch at the left. 

 Drawn from photograph. 



spread as they do when 

 mature and becoming 

 dry, in order that the 

 seeds may be set at 

 liberty. The general 

 outline of the cone is lanceolate, or long oval, and somewhat 

 curved. It measures about 10-15 cm long. If we remove one 



Fig. 164. 

 Mature cone of white pine 

 at time of scattering of the 

 seed, nearly natural size. 



