EEPEODUCTIVE ORGANS 



115 



Fig. 115. A win< 



spores called pollen 

 and occasionally 

 falling upon the 

 right spot for 

 germination. 

 With s u c h a n 

 agent of transfer 

 the pollen must 

 be very light and 

 powdery, and 

 also very abun- 

 dant, for it must 

 come down al- 

 most like rain to be 



:ed seed of Bignonia.— After Strasburger. 



grains being scattered by the wind, 



Fig. 117, Winged fruit of Ptelea— After 

 Kerxer. 



Fig. 116. Winged fruit of maple. — After Kerner. 



certain of reaching the right places. 

 Among the gymno- 

 sperms (pines, hem- 

 locks, etc.) this is the 

 exclusive method of 

 pollination, and when a 

 pine forest is shedding 

 pollen the air is full of 

 the spores, which may 

 be carried to a great 

 distance before being 

 deposited. Occasional 



