THE PROBLEM 31 



houses are of this epiphytic nature, and so are 

 most members of the Pineapple family. Some- 

 times epiphytes adapt themselves in extraor- 

 dinary ways to their peculiar mode of life. In 

 some Orchids, the leaves are not developed, and 

 the roots have taken their place, turning green 

 and flattening themselves out over the bark of 

 the tree on which they grow like the frond of 

 a Liverwort. On the other hand, the Old Man's 

 Beard of Western South America (Tillandsia 

 usneoides) has lost its roots altogether, and 

 hangs loose on the branches, in long grey tufts, 

 like a lichen. An East Indian epiphyte (Dis- 

 chidia Rafflesiand) has converted its leaves into 

 pitchers, which act as "natural flower-pots," 

 collecting soil brought by ants and the water 

 that drips from the tree. The epiphyte sends 

 down its roots into the pitchers, to feed on the 

 soil which has accumulated in them. 



The "natural flower-pots" of Dischidia must 

 not be confounded with the pitchers of the 

 better-known pitcher-plants such as Nepenthes; 

 here the pitchers serve as traps for insects, for 

 these plants, like our Sundew and the Venus's 

 Fly-trap, are carnivorous, reversing the usual 

 order of nature, and feeding on animals instead 

 of animals feeding on them. 



This is a curious example of the enterprise 

 shown by Angiosperms; we have another in 



