DISPERSAL OF WEED SEEDS 



tail. It is but fair to say that these weeds were 

 mostly on soil that had been brought in by the 

 railway company for the purpose of raising the 

 grade of the road bed. Many of these weeds 



Fig. 23. Plantain. 

 (C. M. King.) 



Fig. 24. Two kinds ef 

 smartweed. (C. M. King.) 



have, however, in the course of five years, spread 

 to the surrounding territory, and the problem of eradi- 

 cating them has already become serious. 



Highways. Highways are an important factor in the 

 distribution of weeds to adjacent fields. No matter how 

 clean the fields are kept, if the seeds of plants like the 



Fig. 25. Seeds found in red clover, i, 2, wild carrot. (C. M. King.) 



cocklebur, Canada thistle, sweet clover, thistle, ragweed, 

 and squirrel-tail grass are permitted to develop and 

 mature along the highways they will naturally spread to 



