7. 



are a large number of fine threads, collectively called the pap- 

 pus. These give it a parachute-like arrangement and permit the 

 seed to sail through the air. This weed owes its wide distribu- 

 tion to the facilities for dissemination. Canada thistle, Bull 

 thistle, Horsewced and many plants of the Sunflower family have 

 similar contrivances. The Tumbleweed is another type of weed 



a Seed of beggar-tick's, ft Spanish needle carried by animals. (C. M. 

 King.) 



Seeds carried by the wind: a golden rod, 6 blue lettuce. (C. M. King.) 



disseminated by the wind. The plant grows in circular form and 

 when mature is severed from the root close to the ground. In 

 this form it rolls over and over scattering the seed. The Rus- 

 sian thistle is like it, but each seed is attached by a slender thread 

 like body which becomes severed from the plant, drops the seed 

 as it rolls over the ground. 



Water. Weeds are scattered by the water in two ways (a) 

 in a mechanical way, the seeds, plants or roots are carried by 

 the water. I have seen fields covered with wild oats that had 

 come from higher ground along the streams or ridges, stems of 

 Quack grass have been scattered by the water in this way. (b) 

 Many seeds have bladders filled with air, as in Dock. The 

 three cornered seed is surrounded by the calyx; one or more of 

 the lobes contain a cylindrical body called the tubercle, this is 

 filled with air and makes the seed boyant which enables it to 

 float down the stream and scatter the seed wherever it is lodged. 

 The seeds of Peppergrass when moistened become mucilaginous 

 and cling to the hoofs of animals or shoes and in this way steal 

 a ride. 



Animals. Various animals like cattle, sheep, horses, squirrels, 



