378 



FOUNDATIONS OF BOTANY 



The student should be able, from his own- observations on 

 the falling fruits of some of the trees and other plants above 

 mentioned, to answer such questions as the following : 



What is the use of 

 the wing-like append- 

 ages? of the tufts of 

 hairs ? 



Which set of con- 

 trivances seems to be 

 the more successful of 

 the two in securing 

 this object? 



What particular 

 plant of the ones avail- 

 able for study seems 

 to have attained this 

 object most perfectly ? 



What is one reason 

 why many plants with 

 tufted fruits, such as 

 the thistle and the dan- 

 delion, are extremely 

 troublesome weeds? 



A few simple experi- 

 ments, easily devised 

 by the student, may 

 help him to find an- 



FIG. 267. Winged Fruits of Thistle ; Winged Seeds swers to the questions 

 of Milkweed. above given. 1 



448. Tumble weeds. Late in the autumn, fences, par- 

 ticularly on prairie farms that are not carefully tilled, often 

 serve as lodging-places for immense numbers of certain 

 dried-up plants known as tumbleweeds. These blow 

 about over the level surface until the first snow falls and 



See Kerner and Oliver, Vol. II, pp. 833-875 ; also Seal's Seed Dispersal 



