28 



FARM FRIENDS AND FARM FOES 



lies in exterminating them to as great an extent as possible. 

 And it is especially important that there be cooperation to 

 this end among all the landowners of a locality. 



POISON IVY 



Poisonous Trees and Shrubs 



The Choke Cherry is one of the commonest and most 

 dangerous of shrubs. It is found along roadsides, woods 

 and fences, throughout the greater part of Canada and the 



United States. Its seeds are 

 scattered everywhere by birds, 

 and it spreads rapidly by un- 

 derground stems. As the leaves 

 wilt after the bushes are cut, 

 Prussic acid, a virulent poison, 

 is formed within them by the 

 combination of two nonpoison- 

 ous substances. This is often 

 fatal to cattle that feed upon 

 the withering branches. Conse- 

 quently it is desirable to prevent the growth of Choke 

 Cherry bushes, and to leave no freshly cut leaf-bearing 

 branches within the reach of stock. 



Black Cherry leaves also develop this poison as they 

 wither, and perhaps the same is true of other wild cherries. 

 Certain species-of Laurel, especially the Mountain Laurel 

 and Sheep Laurel or Lamb-kill, are poisonous to stock. 

 The leaves and green stems contain a principle that is even 

 more fatal than strychnine. 



Among the more important shrubs that are likely to 

 spread from walls and fences into the adjacent fields are 

 the various species of Sumachs. The seeds of these are 

 left along fences by birds, and the resulting plants, when 



