324 



EXPERIMENTS WITH PLANTS 



lens, we see that they are covered with spines, prickles, 

 hooks, claws or barbs of the most various description, 

 so .that we may say that plants have tried 

 almost every possible device in solving 

 this particular problem. Many fruits are 

 sticky, and will cling even to the smooth- 

 est surfaces, while some, like 



176. Fruit of Bur , 



clover. the Tar weeds, are both sticky 

 and armed with hooks, so that they cling 

 equally well to rough arid smooth objects. 



A simple way to test the efficiency of these 

 devices is to toss them against a blanket 

 hanging vertically, and notice which cling 

 most readily to its surface. Examine the 

 coats of animals to see what plants are most 

 successful in attaching their seeds or fruits. 

 Many seeds are carried about by birds 

 (and other animals) in the mud which sticks 

 to them. This is especially the 

 case with such birds as frequent 

 swampy and muddy places. Birds distribute 

 seeds principally, however, by eating the 

 berries and other fleshy fruits, and af ter- 

 ns Fruit of war ds voiding the seeds uninjured. Such 

 ciotbur. fruits are usually sour, acrid or otherwise 

 disagreeable to the taste during their development ; but, 

 when ripe, become sweet and fine-flavored: at the same 

 time they assume a characteristic and usually conspic- 



