AS ASCIDIA OK PITCHERS. 



169 



302. Ascidia or Pitchers, or tubes open at the summit, represent 

 another remarkable form of leaves. These occur in several plants 

 of widely ditferent families. If we conceive the margins of the 

 dilated part of the leaf of Dioniea to curve inwards until they meet, 

 and cohere with each other, there would result a leaf in form not 

 unlike that of Sarracenia purpurea, the common Pitcher-plant or 

 Sidesaddle Flower of the Northern United States (Fig. 300). So 



the tube or pitcher has been supposed to answer to the petiole, and 

 the hood at the summit to the blade. And this view is strengthened 

 by a Pitcher-plant of the same family (Heliamphora, Fig. 299), 

 discovered by Mr. Schomburgk in the mountains of British Guiana, 

 in which the pitcher is not always completed quite to the summit, 

 and the hood is represented by a small concave terminal appendage. 

 In the curious Nepenthes (Fig. 301), the petiole is first dilated into 

 a kind of lamina, then contracted into a tendril, and finally dilated 

 into a pitcher, containing fluid secreted by the plant itself; the orifice 

 being accurately closed by a lid, which from analogy was supposed to 

 represent the real blade of the leaf. The study of the development, 

 however (recently made by Dr. Hooker), does not confirm this 

 hypothesis. The whole pitcher of Nepenthes is only an anom- 

 alous appendage of the tendril-hke prolongation of the midrib of the 

 real blade of the leaf. A new Pitcher-plant of the Sarracenia family 

 (the Darlingtonia), discovered by Mr. Brackenridge in California, 



FIG. 299. Pitchers of Heliamphora ; 300, of Sarracenia purpurea ; 301, of Nepenthes. 

 302. A phyllodiuni of a New Holland Acacia. 303. The same, bearing a reduced compound 

 blade. 



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