﻿Nichols: The vegetation of Connecticut 181 



enough, say within five or six feet of the surface, a higher order 

 of plants — higher in an ecological sense — is able to develop, viz., 

 plants whose leaves float upon the surface (Fig. 5). Most im- 

 portant among these are the water-lilies {Castalia odorata and 

 Nymphaea advena), from the almost invariable presence of which 

 this phase in the succession is called the Water-lily Stage. As a 

 rule the water-lilies come in with such force that they crowd out 

 most of the submersed aquatics, for the shade produced by their 

 large leaves is so great that nothing can live underneath them. 

 One of the most remarkable structural peculiarities of the water- 

 lilies is seen in their enormous rhizomes. These organs persist 

 year after year, growing in length, sending out roots into the soft 

 muck, and branching at intervals. In Nymphaea advena they 



frequently acquire a length of fully eight feet, with a diameter of 

 from two to three inches. When present in abundance they fulfil 

 an important ecological role by holding together the loose deposits 

 at the bottom of the lake. This same end is accomplished, though 

 probably less efficiently, by the weak, slender roots and rhizomes 

 of various submersed aquatics. Frequently other plants with 

 floating leaves, such as Brasenia Schreberi and Nymphoides lac- 

 tmosum, together with Potamogeton epihydrus and similar hetero- 



