Jennings : A Botanical Survey of Presque Isle. 387 



comparatively short time a deposit of muck-soil. The protection 

 afforded by the outlying Scirpus formation is usually so efficient, that 

 almost no sand is carried into the habitat even in the most violent 

 storm, and as a consequence the upper six or eight inches of the soil, 

 when finally built up to the water level, is usually found to be a pure 

 black or dark brown humus. 



The Cladium-Calama^rostis Formation. 

 With the formation of a humic soil, the surface of which is ordi- 

 narily during the summer above water-level, there is created a habitat 

 in which the Phragmiies-Typha formation is forced to give way to the 

 C/adii/m-Caiamagrosfis formation, thus constituting a wet meadow : 

 Fades. — 



Cladiiim mariscoides, Calamagrostis canadensis. 



Principal Species. — 



Aster ericoides, Parnassia caroliniana, 



Gentiana andreivsii. 

 Secondary Species. — 



Fragai-ia americana, Rubus hispidiis, 



Linian medium, SoUdago canadensis, 



Leptorchis loeselii, Blephariglottis peramcena, 



Dryopteris thelypteris Argentijia anserina, 



Polytrichiim sp. 

 One of the finest examples of the wet-meadow formation is to be 

 seen at Y. Here the meadow occupies a depression about one-fourth 

 of a mile in length and about twenty rods wide. It is bordered on nearly 

 all sides bv shrubs, but at the eastern end has an opening into the bay 

 which is now occupied by the Pliragmites-Typha formation, while 

 farther out is the Scirpus formation. 



There is here practically no difference between the Cladium-Cala- 

 magrostis formation and the same formation around the ponds and 

 lagoons, excepting that the C/adium mariscoides consocies plays here 

 a much less important part in the succession, the Calamagrostis cana- 

 densis consocies almost immediately succeeding the Phragmites-Typha 

 formation. This is probably due to the somewhat different edaphic 

 conditions obtaining in the two habitats. The soil around the newly 

 formed ponds and lagoons, when first occupied by the Cladium, is 

 largely sand with more or less humus, the Calamagrostis coming in 

 with the accumulation of humus. In Y, however, the soil, as accu- 



