RELATION TO ENVIRONMENT 



507 



themselves to the roots of other plants, and doubtless extract food 

 from them. 



Some of the most pronounced 

 instances of parasitism among 

 the higher plants are seen in the 

 Eafflesiaceae, where the degener- 

 ation of the plant body is so 

 complete that it grows like a 

 Fungus within the body of the 

 host, finally bursting through 

 to produce its enormous flowers. 



A distinction must be made 

 between proper parasites, which 

 penetrate into the body of the 

 host, and mere epiphytes, which 

 attach themselves superficially. 

 It is true that the latter may 

 cause injury, or even death, to 

 the host, by smothering or 

 strangling it, but the epiphyte 

 in no case feeds upon the host. 

 A very marked instance of the 

 destruction of the host by a 

 purely epiphytic plant is seen 

 in several tropical species of 

 Ficus. These germinate upon 

 the branches of various trees and 



send down aerial roots which , 



u 11 1.1 -i mi * IG - 4<o. Monotropa umflora. A sapro- 



finally reach the earth. These phyte . (A fter BAILEY.) 



aerial roots finally completely 



enclose the trunk of the host-tree, which is at last killed, leaving the 



Fig supported by a hollow trunk formed of the united aerial roots. 



CARNIVOROUS PLANTS 



Some plants, which are not properly parasites, nevertheless obtain 

 part of their nitrogenous food from the bodies of animals which they 

 capture. While most of these carnivorous plants belong to the Sper- 

 matophytes, it is said that certain tropical Liverworts develop traps 

 upon their leaves, by means of which they capture small crustaceans, 

 which they presumably use as food. 



Among the Spermatophytes several types of traps are found, these 

 being especially characteristic of certain families, e.g. Sarraceniaceae, 

 Droseracese, Utriculariaceae, etc. The Sarraceniaceae comprise two 

 genera in the United States, Sarracenia of the Atlantic states, and 



