DION^A: ALDROVANDA: NEPENTHES 271 



also present, but it is doubtful whether they excrete a digestive 

 fluid. A description of this remarkable plant is given by 

 Arber (Fig. 37). 



(b) The Nepenthaceae are old-world tropical plants most 

 abundant in the Malay Archipelago. They are frequently 

 cultivated in hot-houses and many hybrids have been raised. 

 They are usually small shrubs, epiphytes, climbers, or 

 ramblers ; some attain a length of 90 feet. The leaves may 

 be very large — over a 

 yard long. The broad 

 sheathing blade runs 

 into a tendril. Usually 

 this tendril, after mak- 

 ing a turn round some 

 suitable support, bends 

 vertically down and 

 then curves up and 

 terminates in the cha- 

 racteristic pitcher, as 

 large as a quart pot in 

 some species, in others 

 not bigger than a 

 thimble. The extreme 

 tip of the leaf forms a 

 lid arching over the 

 pitcher mouth. The 

 pitchers are often bril- 

 liantly tinted in reds 

 and purples (Fig. 38). 



The pitcher is thus a modified part of the leaf tip. It is 

 not formed by all leaves. Those near the spike-like inflore- 

 scence frequently end in the tendril. Goebel (1889) modi- 

 fies an older observation of Sachs, that pitchers are formed 

 only if the tendril has twined round a support, by adding 

 that this is true only in the older plants of certain species. 

 Thus Nepenthes ampullaria forms no pitchers on functioning 

 tendrils. Seedlings and cuttings regularly form pitchers 

 before climbing sets in. The tendril of Nepenthes must be 



Fig. 37. — Aldrovanda vesiculosa, shoot with 

 two whorls of leaves. X 2. (After 

 Caspary.) 



