40 



A TEXT-BOOK OF BOTANY 



one of the sticky drops, the hair begins to curve inward, and 

 presently presses its victim down upon the surface of the 

 blade. In the case of a larger insect, several of the mar- 

 ginal hairs may join to- 

 gether in holding it, or the 

 whole blade may become 

 more or less rolled inward. 

 (6) Leaves of Dioncea. 

 This is one of the most 

 famous and remarkable of 

 insect-trapping plants, be- 

 ing found only in certain 

 sandy swamps near Wil- 

 mington, N. C. The leaf- 

 blade is constructed so as 

 to work like a steel trap, 

 the two halves snapping 

 together, and the marginal 

 bristles interlocking like 

 the teeth of a trap (Fig. 



FIG. 40. Three leaves of Dioncea: two with 40). A few Sensitive hairs, 

 the traps open, one with trap shut on TI r i i i 



aninsect.-AfterKERNER. ^ k ^ feelers, are developed 



on the leaf surface ; and 



when one of these is touched by a small flying or hover- 

 ing insect, the trap snaps shut and the insect is caught. 

 Only after digestion, which is a slow process, does the trap 

 open again. Dioncea is popularly known as the "Venus 

 fly-trap." 



Sarracenia, Drosera, and Dioncea are conspicuous repre- 

 sentatives of the so-called carnivorous or insectivorous 

 plants, all of which capture insects and use them for food. 

 They are green plants, so that they manufacture carbo- 

 hydrates; but for some reason they supplement their food 

 manufacture with a supply of food already manufactured, 

 and obtained from the bodies of captured insects. 



