DISCUSSION OF DEPENDENT PLANTS 



387 



357. The Venus 's-flytrap. In the Venus's-fiytrap, which 

 grows in the sandy regions of eastern North Carolina, the mech- 

 anism for catching insects is still more remarkable. The leaves, 

 as shown in Fig. 315, termmate in a hinged portion which is 

 surrounded by a fringe of 

 stiff bristles. On the in- 

 side of each half of the 

 trap grow three short hairs. 

 The trap is so sensitive 

 that when tlie.se hairs are 

 touched it cloises rather 

 rapidly, and very generally 

 succeeds in capturing the 

 fly or other insect which 

 has sprung it. The im- 

 prisoned insect then dies 

 and is digested, — some- 

 what as in the case of those 

 caught by the sundew, — 

 after which the trap re- 

 opens, and is ready for 

 fresh captures. 



358. Advantages of ani- 

 mal food. It has been 

 claimed that there is an 

 advantage that comes to a 

 good many kinds of plants 

 which catch insects and ab- 

 sorb the digested products. 

 Carnivorous plants belong 



usually to one of two classes as regards their place of growth ; 

 they are bog plants or air plants. In either case their roots 

 find it difficult to secure much nitrogen-containing food, — 

 that is, much food out of which protein material can be built up. 

 Animal food, being itself largely protein, is admirably adapted 

 to nourish the growing parts of plants, and those which have 



Fig. 314. Common pitcher plant 

 [Sarracenia purpurea) 



At the right one of the pitcher-like leaves 

 is shown in cross section 



