120 



ESSENTIALS OF BOTANY 





'^s 



140. Carnivorous Plants. — In the 



ordinary pitcher-plants (Fig. 83) the 

 leaf appears in the shape of a more or 

 less hooded pitcher. These pitchers 

 are usually partly filled with water, 

 and in this water very many drowned 

 and decaying insects are commonly 

 to be found. The insects have flown 

 or crawled into the pitcher, and, once 

 inside, have been unable to escape on 

 account of the dense growth of bristly 

 hairs about the mouth, all pointing 

 inward and downward. How much 

 the common American pitcher-plants 

 depend for nourishment on the drowned insects in the 

 pitchers is not definitely known, but it is certain that some 

 of the tropical species 



Fig. 85. Blade of Leaf 

 of Sundew. (Some- 

 what magnified.) 



require such food.^ 



In other rather com- 

 mon plants, the sun- 

 dews, insects are 

 caught by a sticky 

 secretion which pro- 

 ceeds from hairs on the 

 leaves. In one of the 

 commonest sundews 

 the leaves consist of a 

 roundish blade borne 

 on a moderately long 





(Some- 



FiG. 86. Leaves of Sundew, 

 what magnified.) 



The one at the left has all its tentacles closed 

 over captured prey ; the one at the right 

 has only half of them thus closed. 



1 Where the Sarracenia is 

 ahundant it will be found in- 

 teresting and profitable to make a careful class study of its leaves, 

 Geddes' Chapters in Mudeni Botany, Chapters I and II. 



See 



