146 The Flower 



on the flower in search of honey and the weight of his 

 body on the point of the lower petal presses it down and 

 releases the stamens and pistil which were shut up 

 inside it. The stamens spring out and dust all the under 

 side of the bee's body with pollen. The pistil is still 

 quite young, and must go on growing before it is ready 

 to receive pollen grains. The bee now flies on to an 

 older flower. Its stamens are old and have lost all their 

 pollen, but the pistil has grown long, and, as it brushes 

 against the under side of the bee where the pollen from 



Fig. 73. Horse-chestnut flowers in two stages. A. The pistil is ripe 

 but the stamens are not. B. The stamens are ripe and the pistil 

 is withering. 



the first flower is, some of the pollen grains stick to the 

 pistil and thus cross-fertilise the flower. 



A case that is also found, although not as often as 

 this last one, is when the pistil is ready before the pollen 

 boxes are open, so that to fertilise the flower a bee 

 must have first been to an older flower in which the 

 pollen is ready for distribution. If you examine horse- 

 chestnut flowers in different stages you will see that in 

 the younger ones the pistil sweeps upwards so that it 

 rubs against any bee that visits the flower, while the 

 stamens hang down out of the way (Fig. 73). In older 

 flowers the stamens have grown up till they are in very 



