CIIAI'TKR XXVIII 



PECULIARITIES OF PLANT LIFE 



273. Unusual Plants. — hi order to live, all plants must. 

 have conditions favorable to their vital processes, and 

 many of them develop special modifications which aid the 

 plant in the struggle for existence. Sonic of the modi- 

 fications already studied in this book arc the arrangement 

 of leaves or the length 

 of petioles to secure air 

 and light ; the presence 

 of color, odor, and nec- 

 tar, devices to attract 

 insects and thus secure 

 the pollination of 

 flowers ; and the use 

 of wings, pappus, and 

 hooks to secure the 

 distribution of seeds. 

 Many of the carnivorous 

 and parasitic plants are 



remarkable for the modifications which make it possible 

 for them to obtain nitrogen, an clement lacking in the 

 food supply of their particular environment. 



Tfie Pitcher Plant. — The leaves of this plant form a 

 sort of vase which retains water in the bottom. When 



insects crawl into the leaf, their escape Is prevented by 

 hairs which grow around the opening on the inside and 

 point downward, and the unfortunate victim, exhausted 



389 



Figure 423. 



Photograph of Pitcher 

 Plant. 



