April, 1908.] The Vegetation oj Cedar Point. ZZ^ 



" Salix sp. " Formation around the lagoon at the northeast corner 

 of the peninsula. As exemplified along the Bar the structure is 

 as follows: 



Facies: Salix discolor, 

 Salix lucida, 

 Salix amygdaloides. 

 Principal Species: Solidago canadensis. 

 Secondary Species: 



Salix cor data, Lycopus americana, 



Cornus antomum, Cornus stolonifera, 



Rhus hirta, Rosa Carolina, 



Cephalanthtis occidentalis , Cicuta maculata, 

 Epilobium adenocaulon, Mimulus ringens, 



Impatiens hiflora, Stachys aspera, 



Teucrium canadense, Thaspium barbinode. 



The conditions of environment brought about by a rise in 

 water level are such that xerophytic soil with little humus rapidly 

 passes through the mesophytic to the hydrophytic stage and this 

 is evidently not so well suited to the Salix discolor-lucida Thicket 

 Formation as is a similarly situated, humus-rich soil, which, 

 with the elevation due to the accumulation of vegetable humus 

 has passed from hydrophytic to more mesophytic edaphic condi- 

 tions, as is ordinarily the case around marshes and ponds. 



In a few places this shrub formation alternates with the 

 Calamagrostis Wet Meadow Formation, but, as this is of compara- 

 tively limited extent as compared with the wet meadow occurring 

 in connection with the Cove Habitat near the Laboratory, a dis- 

 cussion of its structure will be taken up under the treatment of 

 the Cove Habitat. 



The Rhus hirta Thicket Formation. 

 This formation is sparingly developed along the marsh shore 

 of the Bar Section but it is comparatively not vigorous and does 

 not form areas of any considerable size. It sometimes borders 

 the preceding shrub formation {Salix discolor-lucida Thicket 

 Formation) or the wet meadow formation, or it may directly 

 adjoin the Phragmites-Typha Marsh Formation. In many places 

 there is a direct transition from the Sand Plain of the Bar Section 

 to the Marsh Formation with no intervening shrub or meadow 

 zone. 



The cottonwoods in the Bar Section are not of great age and 

 they have undoubtedly been such as have accomplished ecesis 

 in the edge of the marsh where the disseminules were buried 

 under the indrifting sand ; conditions almost identical with those 

 obtaining along the wet bank of a newly formed beach lagoon. 

 In a few places towards the Dune Section Ulmus americana 

 seedlings were found along the shores of the marsh under such con- 



