Jennings: A Botanical Survey of Presque Isle. 391 



Fades. — 



Castalia iuberosa, Nymphcea advena. 



Secondary Species. — 



Pontederia cordata, Potamcgeton natans, 



Potaviogeton lonchitcs, Potnmogeton heterophyllus, 



APyriophylliDH spicaiiim, Utricularia intermedia, 



Utricularia vulgaris, Sagittaria latifolia, 



Naias flexilis, Philotria canadensis. 



Wherever the Phragmites-Typha formation, or in some cases even 

 the Scirpus formation, has been disturbed, as in making an opening 

 through the vegetation for a passage to a boat-landing, the Castalia- 

 NymphcBa formation, at least the secondary species, will soon come in. 

 The formation in this case is of course to be regarded as a secondary 

 formation, and, if left undisturbed, would soon give place again to the 

 normal formation. Cove formations very similar to those at Presque 

 Isle are to be seen highly developed along the Sandusky Bay side of 

 Cedar Point, Ohio, but there the Castalia- Nyniphcea\% more important 

 as a constituent of the vegetation, ranking relatively as high as does 

 the Phragmites-Typha formation/^ 



The Phragmites-Typha Formation. 



This formation in a sheltered cove is usually either dominated or 

 entirely replaced by the Typha latifolia consocies, the latter forming a 

 very dense vegetation, giving but scant opportunity for the develop- 

 ment of secondary species. This formation builds up a humus-soil 

 which is finally invaded by the following shrub-formation. 



The Rhits-Alnus Formation. 

 On account of the rapid accumulation of humus by the Typha zone 

 that zone has a distinct slope from the outer to the inner edge, and is 

 comparatively narrow, being followed closely by the Rhus-Alnus for- 

 mation without the occurrence of an intervening Cladium-Calama- 

 grostis zone. The Rhus-Alnus zone is much the same as in the 

 marsh habitat, the Alnus incana consocies predominating. Among 

 the secondary species are here to be included Hibiscus moscheutos and 

 Sambucus canadensis. This formation is ultimately followed by the 

 Ulmus-Acer formation, as described for the marsh habitat. 



^'^ Jennings, O. E. "An Ecological Classification of the Vegetation of Cedar 

 Point." /. ^.,pp. 334-338. 



