304 



HXPERIMESTS WITH PLANTS 



ST(q-M/l- 



pollination does not take place, for the reason that the 

 stigma is not yet mature. In the process of develop- 

 ment it is slowly pushed up, thus gradually expelling 

 the pollen from the tube so that it can be carried away 

 by bees. When this is accomplished it opens up, as in 

 Fig. 166 {B), exposing the smooth surface, which is 

 the receptive part: the pollen which is now deposited 



on it comes from another 

 flower. Good examples of 

 this arrangement will be 

 found in the Daisy, Aster, 

 Cosmos, Sunflower, Core- 

 opsis, Zinnia, etc. 



Another method is by 

 placing the anthers and 

 stigma in different posi- 

 tions. This is illustrated 

 by the Iris (Fig. 167) . As 



1G7. Iris flower, showing how the stigma thc bcC CnterS the fll^WeV 

 iirst removes the pollen from the bee, 



™p^i;!twerire'a1^4r£^^otrer the stigma scrapes off 

 "°"^" some of the pollen with 



which its back is covered: as it goes deeper into the 

 flower its back receives a fresh supply from the an- 

 ther: as it backs out of the flower this pollen is not 

 deposited on the stigma (owing to the manner of its 

 attachment to the style), but is carried on to the next 

 flower. 



The behavior of the Partridge -beriy (also called 



