INSECTIVOROUS PLANTS 365 



3 and 4). These have suggested both the common and 

 scientific names for the plant Bladderwort and Utricularia. 

 Several species occur in Britain, and all are remarkable in 

 that they never possess roots. The shoots float freely in 

 the water, but when in flower, the inflorescence is raised 

 into the air. The bladders are curious ' eel-traps ', filled 

 with water and provided with ' doors ', which open only 

 from the outside. Small aquatic animals may enter, but 

 are unable to escape. After swimming about for a time, 

 they die and are decomposed by the action of bacteria, 

 and the products of their decay are then absorbed by 

 the bladder. The Bladderwort probably does not secrete 

 a digestive ferment and thus its mode of nutrition is that 

 of a partial saprophyte. 



In the Indo Malayan region and elsewhere, a number of 

 bog-plants occur which have large and remarkable water- 

 pitchers, and many of these may be seen in hothouses and 

 botanic gardens. Fig. 234, 5 and 6, shows the leaves of 

 two of these Pitcher-plants, which are species of Nepenthes. 

 The midrib of the large leaf-blade is continued as a long 

 tendril (t), which serves as an organ of attachment to a 

 neighbouring plant, and the tip develops into a large pitcher 

 with water at the bottom and overhung by a lid. Round 

 the mouth is a firm, smooth rim, projecting inwards and 

 fringed with sharp teeth. The outer surface is blotched 

 with various shades of red, brown, and green, and so is 

 attractive to insects. At the entrance are honey-glands, 

 and below them the surface is glazed and smooth, forming 

 a ' slide-zone '. On reaching this, insects find it easy to 

 descend into the water, where they are drowned. Digestion 

 is brought about by ferments secreted by the glands of the 

 pitcher. 



Some pitchers are formed from whole leaves, as in the 

 Side-saddle Flowers (Sarracenia) of North America ; while 

 in Cephalotus, an Australian Pitcher-plant, division of labour 



