334 CONTRIBUTIONS FROM THE NATIONAL HERBARIUM. 



roots to be exposed. The scarcity of aquatic vegetation is probably 

 due to the packed and shifting sand where the water is shallow and, 

 where it is deeper and the bottom muddy, to the dark color of the 

 water which excludes the sunlight. 



FLORA OF THE BANKS. 



The vegetation on the edges of the lake presents quite a different 

 aspect at the western and eastern ends. At the western end there is 

 a low pocosin over which forest fires sweep at frequent intervals. 

 The eastern half is protected by swamps from the fires and the 

 ground is covered with a growth of large trees, consisting largely of 

 Taxodium distichum, Nyssa biflora, Quercus nigra, Ilex opaca, and 

 Liquidambar styraciflua. The undergrowth is quite dense and is char- 

 acterized by Morella cerifem, Leucothoe racemosa, Eupatorium macula- 

 turn, Cyrilla racemifiora, Pieris nitida, Ilex cassine, Arundinaria tecta, 

 Magnolia virginiana, Clethra alnifolia, and Cornus alter nifolia. Wher- 

 ever soil has been caught on the stumps or knees of the Taxodium dis- 

 tichum growing in the lake this soil supports a growth of some kind, 

 generally Eupatorium maculatum or Clethra alnifolia. The trees are 

 usually festooned with Dendropogon usneoides or sometimes Usnea. 

 Polypodium polypodioides, lichens, mosses, and liverworts all grow 

 on the trees in great abundance. Climbing over the trees and shrubs 

 are a large number of vines. The chief species are Vitis rotundifolia, 

 SmiUx laurifolia, and Apios apios. Altogether this part of the shore 

 supports quite a luxuriant vegetation, while all of the western half 

 is covered with low pocosin, which consists of bushes a few feet high 

 and briars. 



Scattered through this growth are small pine trees, but the charred 

 remains of those which have been killed by fire are about as numer- 

 ous as the live ones. The physical conditions, except the humus con- 

 tent of the soil, seem to be the same here as at the eastern end, and it 

 is probable that this part of the shore would be covered with trees 

 but for the forest fires, which kill them and burn the humus out of the 

 soil. These forest fires are frequent in this part of the country. 

 The chief plants found in the low pocosin at the western end are 

 Per sea pubescens, Pieris nitida, Hypericum sp., and Smilax laurifolia. 



ALGAL FLORA. 



The algal flora of Great Lake is very scanty. Bacteria are present, 

 however, in groat abundance, especially floating at the surface, on 

 the submerged parts of the mosses, and on the trees near the surface 

 of the water. 



The most abundant alga is Oedogonium which coats the stems 

 and under surface of the leaves of Nymphaea advena. Algse are also 

 found to some extent on the stems of Sacciolepis striata and the 



