DISTRIBUTION OF WEEDS 



found large numbers of weed seeds therein. In some cases 

 hundreds or thousands of seeds of one species were present In 

 a single crop, and if even a small percentage of these passed 

 unharmed through the 

 bird a great deal of 

 weed distribution 

 would be effected. 

 The most abundant 

 seeds were those of 

 fat hen, knotgrass, 

 bindweed, field pansy, 

 persecaria, chickweed 

 and buttercup, but in 

 addition speedwell, 

 goosegrass, plantain, 

 black bindweed, 

 spurry, sandwort, 

 scarlet pimpernel, 

 toadflax, and may- 

 weed were well repre- 

 sented, and a few 

 seeds of several other 

 species were also pre- 

 sent. In a few weeds, 

 as bittersweet (Sol- 

 anum dulcamara) and 

 black nightshade (S. 

 nigrum], seed distri- 

 bution by birds is 

 ensured by special at- 

 tractions, the seeds 

 being enclosed in juicy 

 coloured berries which 

 are eagerly devoured, 

 and many later ejected 

 uninjured, the weeds 

 thus being spread far 

 and wide. 



FIG. 15. HORSETAIL (Equisctum arvense). 



A. Aerial Shoot. B. Underground Stem. 



C. Rootlets. 



B. Distribution by Vegetative Parts ( Vegetative Reproduction]. 



(a) By Underground Stems. 



(a*) Creeping Stems. Some of the weeds that are most 

 difficult to eradicate are provided with elongated branching 



