DISPERSAL OF WEED SEEDS 



over the ground, but becomes buried. The wild oats also 

 has a creeping arrangement. 



Man as an Agent. Nursery stock is responsible for the 

 scattering of a number of weeds and weed seeds. The 

 scattering of quack grass in this way 

 had been reported to us. Canada 

 thistle, ox-eye daisy, and other peren- 

 nial weeds are known to have been car- 

 ried and scattered by this means. 



Wool. Wool is often responsible for 

 the introduction of a great many differ- 

 ent weed seeds. Around woolen mills 

 it is common to find Fuller's teasel, 

 which is so commonly used in carding 

 of wool. The western storksbill 

 (Erodium cicutarium) no doubt owes its 

 origin in this section to having been 

 introduced with wool. There is con- 

 stant danger when getting live stock 

 from the western states that weeds of 

 this character will be introduced. Some members of the 

 borage family like Lappula floribunda have been scattered 

 in this way. 



Cultivation. It is not uncommon to find that weeds are 

 carried from one field to another by cultivators or plows. 

 This is particularly true of quack grass and Johnson 

 grass. 



Impure Seed. Many bad weeds are introduced with im- 

 pure seed. We have during the past season received 

 many specimens of weeds found in clover meadows. 

 These weeds were undoubtedly introduced with clover 

 seed. 



In nearly all instances the farmers stated that they had 

 not observed these weeds, before. Not all of the clover 

 seeds sold by seed merchants contained these weed seeds, 

 much of it being of good quality. 



Fig. 12. Seeds 

 scattered by birds. 

 A cast from crow 

 containing seeds of 

 poison ivy, etc. 

 (U. S. Dept. Agrl.) 



