BROWN — PLANT LIFE OF NORTH CAROLINA LAKES. 339 



phanerogams and algae than is the deeper water of Great Lake. 

 The phanerogams, by giving mechanical support to the algae, may 

 also place these in a more advantageous position in. relation to the 

 sunlight and thus counterbalance to somo extent the harmful effect 

 due to their competition. 



SUMMARY. 



The whole of the bottom of Lake Ellis is covered with vegetation. 

 There are three distinct zones or successions occurring in the same 

 depth of water, but on different soils. The central zone, found on the 

 sandiest soil, is characterized by Eriocaulon compressum, Eleocharis 

 robbinsii, and Myriophyllum. The intermediate zone, on muddier 

 soil, is characterized by PMlotria minor, Sphagnum, Eleocharis inter- 

 stincta, Panicum fiemitomon, NympJtaea advena, and Castalia odorata- 

 The marginal zone, found on the muddiest soil, is composed mostly of 

 grasses and sedges, the chief component being Sacciolepis striata. 



The disposition of the three zones seems to be determined by the 

 character of the soil. The plants of the intermediate zone invade 

 the territory of the central as it becomes muddier by the depositing 

 of debris, while the plants of the marginal zone in turn invade the 

 territory of the intermediate. As this invasion continues the grasses 

 and sedges will occupy more and more of the lake and probably will 

 finally drive out the plants of the other zones. The vegetation in the 

 lake is of recent origin and the invasion seems to be going on rapidly. 

 A few small plants of Pinus serotina, Acer rubrum, and Liquidambar 

 styracijlua are found when the soil comes near the surface of the water. 



Pinus serotina and Liquidambar styracijlua are invading the growth 

 of grasses and sedges from the outer edge. 



The emergent vegetation growing in Great Lake consists of Taxo- 

 dium distichum, Nymphaea advena, Panicum hemitomon, and Xyris 

 caroliniana. The aquatic vegetation is very scanty. In the shallow 

 water this is probably due to the hard, shifting sand which forms 

 the bottom, while in the deeper parts of the lake where the bottom 

 is muddy, the dark color of the water probably excludes too much 

 sunlight to allow the growth of plants. 



The shore of the eastern half of the lake is covered with large 

 trees under which there is a dense undergrowth. The shore of the 

 western half is covered with low bushes and briers and a few small 

 pine trees. The scarcity of trees here seems to be due to forest 

 fires, which sweep over this part of the shore, whereas the other half 

 is protected by swamps. 



The algal flora of Lake Ellis is rich in both species and individuals. 

 The green algae are abundant but not in good condition in the 

 summer season, while the blue green algae are more abundant and 

 more vigorous. The blue green seem to endure the high and change- 

 able temperature better then the green algae. 



