Aquatic Seed Plants 155 



The bladderworts {Utricularia) comprise another 

 peculiar group. They are free-floating, submerged 

 plants with long, flexuous branching stems that are 

 thickly clothed with dissected leaves. Attached to the 

 leaves are the curious traps or "bladders" (discussed in 

 Chapt. VI) which have suggested the group name. 

 Being unattached they frequent the still waters of 

 sheltered bays and ponds where they form beautiful 

 feathery masses of green. They shoot up stalks above 

 the surface bearing curious bilabiate flowers. 



Fig. 65. The water weed, Philotria (Anacharis or Elodea), with 

 two young black-and-green-banded nymphs of the dragonfly Anax 

 on its stem, and a snail, Planorbis, on a leaf. 



The hornwort (Ceratophyllum) is another non-rooting 

 water plant that grows wholly submerged and branch- 

 ing. It is coarser, however, and hardier than Utricu- 

 laria and much more widespread. Its leaves are stiff, 

 repeatedly forking, and spinous-tipped (fig. 6ziyland C). 



The water milfoils (Myriophyllum) are rooted aqua- 

 tics, superficially similar to the hornwort but dis- 

 tinguishable at a glance by the simple pinnate branch- 

 ing of the softer leaves (fig. 64.B). 



Then there are a few very common aquatics that 

 form patches covering the beds of lesser ponds, bogs 



