April, 1908.] 1 he Vegetation of Cedar Point. 329 



the long, cylindrical, stiff, but yet quite flexible, stems being 

 admirably adapted to withstand surf conditions in which the 

 larger, less flexible leaves and stems of Typha with a greater sur- 

 face exposed to the action of the surf, would be broken up and 

 the plant killed. Accordingly we find that part of the marsh 

 exposed to the action of the surf to have the following structure: 



Facies: Scirpus validus, 



Scirpus americanus. 



Principal Species: Dianthera americana. 



Within the formation there is a distinct zonation, the Scirpus 

 validus Consocies occupying the deeper water, often to a depth 

 of four or five feet, while the Scirpus americanus Consocies occu- 

 pies the shallower portion of the habitat, often extending, where 

 the bottom is sandy, out to the water's edge or even onto the wet 

 bank, but on a muck bottom it is usually replaced in water a foot 

 or less in depth by the formation next described. The action 

 of the surf is considerably diminished by stretches of this forma- 

 tion and quite considerable quantities of shifting sand may be 

 stopped and accumulated by the rushes, thus building up the 

 land. 



The Dianthera americana Society occurs in a few places in the 

 habitat of the Scirpus americanus Consocies, being best developed 

 on sand-bars or islands submerged a few inches and over which 

 which there is usually more or less of a current, — practically the 

 condition of a river sand-bar where this plant reaches its best 

 development. The submerged bar along the south side of the 

 entrance to Biemiller's Cove shows this Society very nicely. 



With the accumulation of sand and the consequent shallowing 

 of the water, often also with the accumulation of more or less 

 well defined deposits of partially humified muck, the following 

 formation succeeds the Scirpus Formation: 



The Phragmites-Typha Marsh Formation. 



Facies: Typha latifolia, 



Phragmites phragmites . 



Secondary Species: 



Zizania aquatica, Scirpus americanus, 



Sagittaria latifolia, Persicaria laurina, 



Sparganium eurycarpum, Calamagrostis canadensis, 



Solanum dulcamara, Naumbergia thyrsiflora, 



Nymphaea advena, Dulichium arundinaceum, 



Lemna trisulca, Wolffia columbiana, 



Carex aquatilis, Carex comosa, 



Salix sp., Cephalanthus occidentalis , 



Many of the secondary species of this formation are more or 

 less temporary invaders belonging more properly to other for- 

 mations. The larger part of the formation is made up of the 



