EXERCISE 54 



WHAT ADVANTAGES ARE POSSESSED BY PLANTS HAVING 

 PLUMED SEEDS OR FRUITS? 



Materials. Plumed seeds of several sorts. The several kinds of 

 milkweed, dandelion, goldenrod, and thistle are good. 



Directions for work. Experiment with the seeds in the quiet 

 air of the classroom, as directed for winged seeds. Measure the 

 difference in rate of descent for seeds with the plume and those 

 from which the plume has been removed. Also allow some of 

 the seeds to descend in the vicinity of an open window through 

 which the wind is blowing, and note the results. 



Compare plumed and winged seeds with each other by drop- 

 ping both at the same time from as high .a position as possible, 

 noting relative rate of descent. 



Which kind of plumed seed, among those you have tried, 

 appears to have the better equipment for wide dispersal? In 

 comparing winged and plumed seeds, which did you find gener- 

 ally superior with reference to dispersal? Would this neces- 

 sarily be true of all winged and plumed seeds ? 



Would the height of the plant on which the seeds were 

 produced be important in connection with dispersal ? Would 

 wings and plumes be equally efficient in the case of low plants, 

 such as the dandelion or the thistle ? 



Illustrate your notes with sketches of several different types 

 of plumes. 



References 



BERGEN and CALDWELL. Practical Botany, pp. 146-155. 

 BERGEN and CALDWELL. Introduction to Botany, pp. 166-171. 



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