128 ECONOMIC IMPORTANCE OF GREEN PLANTS 



are harmful. For example, the 

 poison ivy is extremely poison 

 ous to touch. The poison ivy 

 is a climbing plant which at 

 taches itself to the trees or 

 walls by means of tiny air 

 roots which grow out from the 

 stem. It is distinguished from 

 its harmless climbing neighbor, 

 the Virginia Creeper, by the 

 fact that its leaves are notched 

 in threes instead of fives. Every 

 boy and girl should know 

 poison ivy. 



Numerous other poisonous 

 common plants are found, but 

 one other deserves special 

 notice because of its presence 

 in vacant city lots. The Jim- 



Flax grown for fiber. 



son Weed (Datura) is a bushy plant, 

 from two to five feet high, bearing 

 large leaves. It has white or pur 

 plish flowers, and later bears a four- 

 valved seed pod containing several 

 hundred seeds. These plants con 

 tain a powerful poison, and people 

 are often made seriously ill by 

 eating the roots or other parts by 

 mistake. 



Weeds. From the economic 

 standpoint the green plants which 



Poison ivy, a climbing plant which 

 is poisonous to touch. Notice the 

 leaves in threes. 



