FLOWERS AND INSECTS 



135 



Fig. 140. 



A bee obtaining nectar in the pouch of 

 Cypripedium. — After Gibson*. 



will result in rubbing some of the pollen upon the stigma, 

 and in receiving more pollen for another flower. 



In eases of protandry, as the common figwort, flowers 

 in the two condi- 

 tions will be visited 

 by the pollinating 

 insect, and as the 

 shedding stamens 

 and receptive stig- 

 mas occupy the 

 same relative posi- 

 tion, the pollen 

 from one flower 

 will be carried to the stigma of another. It is evident that 

 exactly the same methods prevail in the case of protogyny, 

 as the fireweed (see Fig. 134). 



The Houstonia (see Fig. 135), in which there are sta- 

 mens and styles of different lengths, is visited by insects 



whose bodies fill 

 the tube and pro- 

 trude above it. Iu 

 visiting flowers of 

 both kinds, one re- 

 gion of the body 

 receives pollen 

 from the short sta- 

 mens, and another 

 region from the 

 long stamens. In 

 this way the insect 

 will carry about two bands of pollen, which come in con- 

 tact with the corresponding stigmas. When there are three 

 forms of flowers, as mentioned in the case of one of the 

 loosestrifes, the insect receives three pollen bands, one for 

 sach of the three sets of stigmas. 



93. Warding off unsuitable insects. — Prominent among 

 10 



Fig. 141. A bee escaping from the poach of Cypri- 

 pedium, and coming in contact with the stigma. 

 Advancing a little further the bee will come in con- 

 tact with th.e anthers and receive pollen. — After 

 Gibson". 



