DISPERSAL OF WEED SEEDS 



wheat, 53 flax, 43 buckwheat, and 91 ragweed seeds. 

 The wind was blowing at the rate of 20 miles per hour. 

 There can be no question but that a drift holds a large 

 number of weed seeds 1 . Along our highways one may 

 find, where the snow has drifted, the ragweed and this- 

 tle growing in large numbers. 



Fig. 8. The seed of vegetable oyster plant scattered by the wind. 

 Fig 9. Various "seeds" scattered by drifting snow. A, small rag- 

 weed; B, sunflower; C, foxtail. 



Water. A number of our very troublesome weeds are 

 carried by the water. This is notably true for the "seeds" 

 of docks. Three of the sepals or outer floral envelopes 

 of the flower of the docks each bear an enlarged body 

 called the tubercle, which is hollow. This body, com- 

 bined with the calyx, enables it to float on the water. 

 During our recent wet years, it has been noticed by 



