i68 THE STORY OF PLANT LIFE 



convex externally, with long processes at the mouth. 

 In form the bladder itself resembles a water flea. 

 The longer processes are branched. The entrance is 

 shut by a flap which closes on a collar. It can be 

 easily opened from outside, and springs back after- 

 wards. The walls of the opening are narrowed at 

 certain points and the flap is semicircular so that it 

 cannot be pushed open from inside. Hence the 

 imprisoned fleas die and are soon absorbed and 

 digested by the plant. 



There are few counties in which the Bladderwort 

 does or did not grow, being a native of all parts of 

 the British Isles and of the Channel Islands. In the 

 Highlands it grows at an altitude of 1500 ft., but it 

 is nowhere common and rather local, its former suit- 

 able habitats having been destroyed, as in the case 

 of the Sundew and Butterwort, by drainage. 



Pools, ditches, water channels, ponds and lakes, 

 canals, highland lochs, are the habitats of the Bladder- 

 wort. It is found in the fresh-water aquatic formation 

 in stagnant waters, in waters relatively rich in 

 mineral salts, in the submerged-leaf association, in 

 highland lochs in waters poor in mineral salts, in the 

 free floating-leaf and closed reed-swamp associations. 



In habit the Bladderwort is a rosette plant. The 

 aerial stem, a scape, is leafy. The root-like, floating 

 branches bear numerous leaves. The leaves are 

 spreading, broadly ovate, much divided pinnately, with 

 thread-like blunt segments, with bladders on short 

 stalks at their base and here and there between them. 



