POLLEN-FLOWERS 



Fig. 96. Purple Poppy. Pa paver somniferum 



A pollen-flower 



There is provision for only a single visit, since the entire stock 

 of pollen is exhausted at once. Male bumblebees, which have 

 no occasion to collect pollen, do not visit these flowers. The 

 flowers of the lupine (Lupinus), another genus of the pulse 

 family, are also nectarless. Here the pollen is expelled by a 

 piston mechanism. The five outer stamens, after discharg- 



199 



