302 



FLOWERS 



wind-blown grain of pollen has to reach its destination is 

 even less than that of one carried on the body of an insect. 

 Of wind-blown pollen probably not one grain in many thou- 

 sands ever reaches a 

 stigma, yet the quan- 

 tity produced is so 

 enormous that few of 

 the ovules fail to be- 

 come seeds through 

 lack of polUnation. 



B. Kinds of Pol- 

 lination. — As to that 

 pollen which does 

 reach stigmas, there 

 is not at all the same 

 story in all cases. 

 Different kinds of 

 stigmas are reached, 

 and different kinds of 

 means are used in 

 reaching them. Thus 

 pollination may be 

 classified as to the 

 means by which the pollen is transferred, or as to the 

 stigmas which are pollinated. 



a. As to the Pollen Carrier. — Of the means by which 

 pollen is transferred you have already noted wind, insects, 

 and birds. Of these the first two are by far the most 

 important ; they are the means by which more than ninety 

 per cent of all cross-polHnation is accomplished. Some of 

 the minor agents are worthy of mention. In some close- 



FiG. 123. — Flowers and inflorescences of Rud- 

 beckia, the coneflower or brown-eyed Susan. 



