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certain conditions are most useful may under other 

 circumstances, be exceedingly harmful. For instance, 

 wheat is one of the most useful of all plants, but 

 along the railroad it may be a nuisance. Railroad 

 weeds are those plants which grow in sufficient a- 

 bundance along the railroad either along the right of 

 way or in the ballasted track to be troublesome in 

 getting rid of them. 



Weeds may be either native plants or intro- 

 ductions from Europe, Asia, Africa or South America. 

 Often the primary introcuction of the seeds of these 

 introduced weeds is a puzzle, whether in vegetables, 

 fruits, seeds, grains or animals imported from these 

 countries. The most likely way is in packages of 

 seeds or grains. As a general thing, native plants 

 which have become weeds do not cause nearly so 

 much trouble as the introduced species. These latter 

 spread for the first few years with amazing rapidity, 

 due to changing and bettering of conditions of 

 growth and lack of enemies. Then later parasitic 

 fungi, insects and animals find them suitable as host- 

 plants or food. Thus in time, as they become natural- 

 ized the conditions about balance each other. 



Weeds compared to ordinary plants bear e- 

 normous quantities of seed. Most of them do not 

 depend upon insects for the polination of their 

 flowers. They depend upon themselves for fertilizing 

 and producing their seed. Ingenious means for the 

 distribution of seed, suiting various locations and 

 circumstances, are provided by many weeds. 



To the farmer, weeds are injurious : first, by 

 robbing cultivated plants of moisture light, space and 

 food-elements ; second, by harboring injurious fungi 

 and insects ; last, by the rendering of wheat, rye, oats 

 etc., unmarketable on account of weed-seeds mixed 

 with the grain. 



In talking about railroad weeds, one must first 

 explain that those plants which are weeds to the 

 farmer are not necessarily to be considered weeds to 



