LIFE HISTORIES OF FAMILIAR PLANTS 



Finally, I will take an example of sensitiveness 

 in a flower. In the common barlDerry, the stamens, 

 or pollen-producing organs, are extremely sensi- 

 tive ; in fact, they probably present the best 

 example of active sensibility amongst British 

 plants. You have but to touch the base of these 

 stamens to make them spring instantly forward, 

 towards the side of the ovary, or central part of 

 the flower, which they bear against with consider- 

 able pressure. If the reader will look carefully at 

 the central parts of the flowers shown in Fig. 53 

 (Plate 35), the light-coloured stamens will be seen 

 opened out and pressed back against the petals. 

 But if Fig. 54 (Plate 36) is carefully observed, the 

 flowers there will be seen to be very different ; their 

 stamens have all closed towards the central ovary, 

 and this is simply owing to the fact that I had 

 touched the base of the stamens with the point of 

 a pin — an interesting experiment that the reader 

 may try at any time when the barberry is in flower. 

 Cultivated species of barberry (such as that 

 figured) and the common British species show 

 alike this interesting feature of sensitiveness. 



It remains now to discover what advantages 

 the barberry derives from its sensitive stamens. 

 With this purpose in view, I proceeded one after- 

 noon to investigate. Almost every flower that I 

 examined contained one or more small black 

 beetles, each about half the size of a wheat grain ; 

 there were thousands of them at work amongst the 

 flowers, all as busy as it was possible to be. They 

 were rifling the nectar of the twelve honey glands 



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