166 LEGUMINOUS FLOWERS [CH. 



" prow," and there pollen is discharged and held ; the five 

 shorter anthers do the same slightly further back. 



It must be noted that the style and staminal tube form 

 a stiff spring-like structure. 



When a bee alights on the flower it straddles on the 

 wings (alee) as on a saddle, and as it probes the floral 

 base its weight depresses the wings and bears down the 

 pollen-laden keel also. This pressure causes the keel 

 to split suddenly above, and the pollen is explosively 

 shot out by the sudden liberation of the trigger-like 

 springy stamens and style. 



Meanwhile the long style had pushed its way into the 

 tip of the keel and lay there also like a spring, forcibly 

 held somewhat like a trigger, and at the moment of ex- 

 plosion it rapidly curls upwards and backwards and 

 escapes out of the ruptured keel. 



Two principal events result. In the first place, the 

 bee is dusted with pollen on its ventral side by the short 

 stamens, and on its back by the sharp recoil of the longer 

 stamens. In the second place, the recoil of the style 

 causes the stigma to sharply brush the bee's back and take 

 pollen therefrom, and then it coils up among the exploded 

 and pollen-dusted anthers, so that if the one action fails 

 the other is sure to pollinate the stigma. 



The startled bee, finding no honey, then flies away 

 with the collected pollen. 



Similar mechanisms occur in Genista, Gorse, Robinia, 

 &c., though not always so explosive in character. In 

 Sophora I have seen the dropped flowers in thousands 

 on the ground, and visited there assiduously by bees. 



Another kind of mechanism is seen in the Barberry 

 (Fig. 105). The flowers droop slightly, and the incurved 

 sepals and petals protect the pollen-laden anthers which 

 dehisce by window-like valves and the honey-glands at 



