Aquarium Plants 53 



of considerable beauty and merit. It grows 

 well where it has a sufficiently high tem- 

 perature. 



Pondweed (Potamogeton) is found in many 

 varieties all through the United States. 

 While most of them may be very interest- 

 ing to the botanist, only a limited number 

 are of actual value to the aquarist. It is 

 not easy to distinguish the different pond- 

 weeds, as location, light and quality of 

 water cause remarkable changes in the color 

 and shape of the leaves. One of the best 

 varieties is the, — 



Wavy-leaved Pondweed (Potamogeton cris- 

 pus). As the name indicates, it has wavy 

 leaves, submerged and varying considerably 

 in length, shape and even in color. The lat- 

 ter, if normal, is a brownish green but 

 through the influence of light and quality of 

 water it may change to a bright clear green, 

 while the usually wavy and curly leaves may 

 become almost flat, so that the original spe- 

 cies can hardly be recognized. The plant 



