Distribution and Propagation. 53 



endowed do not grow for lack of proper 

 fertilization; but enough are fertilized to 

 give the farmer much trouble. Hence many 

 sorts of weeds are continually finding their 

 way to new centers, to which they have a 

 passage as silent as it is free. Some of 

 these downy travelers are able to sustain 

 their flight to incredible distances ; others, 

 on account of their greater weight, are car- 

 ried but for short distances. It should cer- 

 tainly fill us with some concern to reflect 

 that the winds while purifying the atmos- 

 phere, are also engaged, especially in cer- 

 tain seasons of the year, in scattering every- 

 where the seeds of many exceedingly 

 troublesome weeds. While it is greatly 

 important that no form of noxious weed 

 should ever be allowed to mature its seed, 

 it is doubly so in the case of weeds, the 

 seeds of which are able to rise in the air. 



Winds distribute the seeds of weeds by 

 their driving as well as by their car- 

 rying power. The seeds of some weeds 

 remain in their capsules long after their 

 season of growth is over ; in some instances 

 even until the approach of spring. These 

 are often shaken out by the force of the 

 winter winds, and are driven incredibly 



