SHEEP-KILLING GRASSES 



The fruit is like that of most grasses, enclosed in a folded 

 leaf, the bract (or glume), which in these particular cases is 

 produced into a very long fine tapering hair or awn. This 

 awn is sensitive to changes in the moisture of the air. It is 

 strongly hygrometric : in wet weather it straightens itself, 

 and it coils into corkscrew spirals in dry weather. The 

 widened part of the base, which contains the grain, tapers 

 into a sharp, very hard point ; upon this there are, on the 

 outside, many stiff hairs, which point backwards away from 

 the sharp tip. 



Now, suppose this fruit to fall on the ground, the awn or 

 tail is sure to be entangled in neighbouring grasses or herbs, 

 but the hard point will rest upon the ground. Every coil 

 and twist made by the entangled awn or tail will push the 

 point a little deeper into the earth, and the backward- 

 pointing stiff hairs will prevent its being pulled out of the 

 soil. 



Therefore all these modified contrivances ensure that the 

 seed will bury itself. 



But supposing that one of these fruits falls upon a 

 sheep's back. Then an exactly similar process will go 

 on. The seed will be forced through the skin into the 

 body of the sheep. In fact, if it should fall above any soft 

 or vulnerable part of the animal, the sheep will very likely 

 be killed. 



As a matter of fact, sheep are said to be killed by these 

 grasses in all those four countries, distant though they are 

 from one another. 



We have endeavoured in this chapter to give some faint 

 notion of the hundreds and thousands of ingenious con- 

 trivances utilized by plants in order to ensure the dispersal 

 and future prosperity of their children. 



267 



