162 



DISPERSAL OF SEEDS 



clothing. The burdock has an 

 involucre with hooked scales, 

 containing the fruits inside. 

 Fig. 280. The clotbur is also 

 an involucre. Both are compos- 

 itous plants, allied to thistles, 

 but the whole head, rather than 

 the separate fruits, is trans- 

 ported. In some compositous 

 fruits the pappus takes the form 

 of hooks and spines, as in the 

 " Spanish bayonets " and " pitch- 

 forks." Fruits of various kinds 

 are known as "stick tights," as 

 of the agrimony and hound's 

 tongue. Those who walk in 

 the woods in late summer and 

 fall are aware that plants have 

 means of disseminating them- 

 selves. Fig. 281. If it is im- 

 possible to identify the burs 



which one finds on clothing, the seeds may be planted and 



specimens of the plant may 



then be grown. 



Review. What advantage is it 

 to the plant to have its seeds 

 widely dispersed ? What are the 

 leading ways in which fruits and 

 seeds are dispersed? Name some ex- 

 plosive fruits. Describe wind-travel- 

 ers. What seeds are carried by birds? 

 Describe some bur with which you 

 are familiar. 



Note. This lesson will suggest 

 other ways in which seeds are trans- 

 ported. Nuts are buried by squirrels 



279. Drupes of the black haw, loved 

 of robins in winter. 



WW' 



280. The cow is carrying burdocks. 



