368 Annals of the Carnegie Museum. 



Eleocharis quadrangulata, Eleochafis obtiesa, 

 Proserpinaca palustris, Calamagrostis canadensis, 



Naumbergia thyrsijlora, Asclepias incarnata. 



The formation as a whole presents very little zonation or alternation 

 within itself. Cephalanthus is the only one of the facies that can ever 

 be said to constitute a distinct consocies, it usually being indiscrimi- 

 nately mixed with the other facies. Rosa Carolina seems sometimes 

 to prefer the outer border of the formation, thus indicating a Rosa 

 Carolina consocies, but in the present stage such association is not 

 prominent. 



The formation constitutes a zone of varying width, in a few places 

 even being absent altogether, but towards the west end of the pond it 

 sometimes reaches a width of about forty feet. The soil is always a 

 saturated muck several inches deep, the pondward side of the zone 

 being usually three to four inches under water and the landward side 

 just above its surface. 



The ecological conditions of this habitat are approximately those 

 of the " undrained swamp" as described by Cowles and others.'^ 

 Cephalanthus is almost invariably one of the most characteristic facies 

 in the shrub-zone around undrained swamps and ponds, where there 

 has been an accumulation of vegetable matter resulting finally in a 

 saturated muck-soil. Towards the southern part of the glaciated area 

 of the northern states the shrub-formation of the morainal ponds and 

 open swamps consists almost always, in large part, of Cephalanthns?"^ 

 Northwards this species gives way to other plants, such as Cassandra, 

 willows, etc. 



At the west end of Cranberry Pond there is an area of about an acre 

 which is now above water most of the year and which might best be 

 described as a mud-flat. The soil is a black muck and it is now 

 sparsely occupied by young Cephalanthus bushes, the open spaces 

 between being partially taken up by Nymphcea advena, small and un- 

 healthy, Hypericum caiiadense,Dulichium arundinaceuni, a.x\d Eleocharis 

 quadrangulaia. This area appears to have only comparatively recently 

 been filled to such an extent that the Nymphcea has had to succumb and 



"'Cowles, H. C. "Physiographic Ecology of Chicago and Vicinity," /. c, pp. 

 147-155, and Coulter, S. M. " An Ecological Comparison of Some Typical Swamp 

 Areas." Ann. Rept. Mo. Bot. Card., 15: 56, March, 1904. 



" Schaffner, J. H., Jennings, O. E., and Tyler, F. J. "An Ecological Study o 

 Brush Lake." Proceed. Ohio Acad. Science, 4: 159-160, 1904. 



