PLANTS DEFEND THEMSELVES 47 



sought after by grazing cattle and sheep, called 

 the Muhleribergia Texana. This grass probably 

 would have become extinct long ago, growing as 

 it does in almost desert soil where pasturage is so 

 much in demand, had it not sought refuge beneath 

 the thorny branches of cacti and mesquite bushes. 

 The cattle fear too familiar proximity to the 

 thousand-pointed cactus, and so, in spite of the 

 seductive freshness of the Muhleribergia f they 

 leave it to flourish in peace under the protection of 

 its spiny and dagger-armed guardian. Even young 

 sheep have learned not to try to reach it, lest they 

 become hopelessly grasped by the prickly cactus, 

 whose sheltering arms defend not only the grass 

 but ofttimes a happy family consisting of rattle- 

 snakes, prairie dogs, and the prairie owl. 



With plants that run away to the protection 

 of stronger plants should be grouped those 

 which hide from their depredators. There are 

 many of these, some of which are very cunning in 

 their methods of escaping detection. Weeds fre- 

 quently hide in among plants which are very simi- 

 lar to themselves: wild seedling lilies are often 

 found among Solomon's-seal ; June grass flourishes 

 undisturbed among beds of phlox; nightshade 

 grows among tomato plants; wild onions slip in 

 among their cultivated cousins ; daisies love the com- 



