April, 1908.] The Vegetation of Cedar Point. 305 



In the older part of this lagoon the Potamogeton Forma cion 

 shows little change from its structure in the youngest part of the 

 lagoon, excepting that the constituent plants are larger and more 

 numerous. At the edge of the water and extending a few inches 

 up onto the wee sand is a zone which ma}' be termed: 

 The Juncus-Eleocharis Formation. 

 Facies: J uncus halticus. 



Eleocharis intermedia. 

 Secondary Species: 



Cyperus rivularis, Roripa palustris. 



Populus deltoides, Salix cor data, 



Salix lucida. 



There is but little change in the outer Populus-Salix zone in 

 this stage, aside from the further growth of the individuals and 

 the appearance of occasional ruderal species. In the oldest and 

 most highly developed parts of the lagoon under consideration 

 the vegetation is in the beginning of what may be termed Stage 

 C, with the following structure: 



Stage C. 



a. The Potamogeton Formation. 



b. The Typha-Scirpus Formation. 



c. The Salix (spp.) Formation. 



d. The Populus-Salix Formation. 



In this stage there is again little change in the Potamogeton 

 Formation, but in the shallow water near the shore, and also 

 taking the place of the Juncus-Eleocharis Formation on the 

 wet bank at the water's edge, there has appeared a new vegeta- 

 tional structure as follows: 



The Typha-Scirpus Marsh Formation. 

 Facies: Scirpus validus, 



Scirpus americanus, 

 Typha latifolia. 

 Secondary Species: 



Sparganium eurycarpum, Juncus balticus, 

 Eleocharis intermedia, Scirpus atrovirens, 



Sagittaria latifolia, Alisma plantago -aquatic a, 



Roripa palustris, Potamogeton natans, 



Castalia tuberosa. 



Among the secondary species are a few, — Alisma, Roripa, 

 Sagittaria, — which are more typicall}- representative of the humus 

 swamp or marsh margin than of a beach lagoon and their presence 

 here is to be regarded as due to the rather large amount of organic 

 matter (drift debris) incorporated into the soil of the habitat. 

 The vegetation of this formation catches considerable sand and 

 contributes quite appreciably to the filHng of the lagoon. 



