SEDGE AND WOOD RUSH. 21 



thus looks like a group of miniature catkins, 

 the upper catkins bright yellow and the 

 under ones delicately frosted with fluffy 

 white. The use of this arrangement is 

 obvious. When the wind shakes the heads 

 so that they bend and jostle against one 

 another, the tallest spikelet on each stalk 

 naturally strikes against the lower spikelets 

 of its neighbours. Thus each plant fertilises 

 the next in order ; and even if the heads do 

 not happen to touch, yet the pollen blown 

 from the one falls forward upon the other, so 

 producing exactly the same result. Indeed, 

 cross-fertilisation is brought about in dif- 

 ferent plants by a hundred such devices ; and 

 to observe the various mechanisms by which 

 it is furthered, forms a fresh and almost 

 endless pleasure for every country walk. 



