BEE FLOWERS 



81 



enough to depress the keel it, of course, does not get the nectar. 

 Very few bees are strong enough to depress the keel of a sweet-pea 

 flower and for that reason sweet-pea flowers are not much visited by 

 bees and are usually self-pollinated. 



The flower of aifalfa has the anthers and stigma held in the 

 keel under tension and when a bee presses the keel down the anthers 

 and stigma fly forcibly upward against the body of the insect. 

 It is a curious fact that east of the IMississippi River alfalfa does not 



Fig. 31.— White clover {Trifolium repens). Final stage, flowers all reflexed 

 and brown colored. (Photograph by John H. Lovell.) 



produce much nectar while in the western part of the United States 

 it is one of the most prolific of honey plants. The honey-bees that 

 visit alfalfa flowers, however, usually do not effect pollination since 

 they steal the nectar through a hole in the side of the corolla. In 

 such a case the symbiosis is antagonistic and not reciprocal. 



Red clover {Trifolium inatense) is pollinated almost entirely by 

 bumble-bees and does not produce seed in the absence of bumble- 

 bees, except in occasional years when Tetrnlonia, one of the solitary 

 6 



