126 STRUCTURAL BOTANY. [107,108. 



leaves, expressly contrived, as if by art, for holding 

 water. The pitchers of Sarracenia, whose several spe- 

 cies are common in bogs North and South, are evi- 

 dently formed by the blending of the involute margins 

 of the broadly winged petioles, so as to form a com- 

 plete vase. The broad expansion which appears at the 

 top may be regarded as the lamina. These pitchers 

 contain water, in which insects are drowned, being 



Ascidia.391, Nepenthes. 392, Sarracenia psittacina. 393, S. purpurea. 394, S. Gronovii, /?. Drum- 

 mondil. 395, Acacia heterophylla its phyllodia. 



prevented from escaping by the deflexed hairs at the 

 mouth. Other pitcher-bearing plants are equally curi- 

 ous ; as Darlingtonia of California, Nepenthes and 

 Dischidia of the East Indies. In Dionsea of North 

 Carolina, the leaves are transformed to spiny, snapping 

 fly-traps ! 



323. Many weak-stemmed water-plants are fur- 

 nished with Air-bladders, or little sacks filled with air 

 to buoy them up near to the surface. Such are the 

 bladders of the common Bladderwort, formed from the 

 leaf-lobes. In the Horned-bladderwort, the floats are 



