1901 | PHYSIOGRAPHIC ECOLOGY OF CHICAGO 151 
Pullman. In this case the soil is rather deep and rich, in which 
respects there is agreement with the first type rather than the 
second. Grasses and sedges, but of a more luxuriant type, domi- 
nate here also, and with them are found such plants as Cepha- 
lanthus occidentalis, Aspidium Thelypteris, Onoclea sensibilis, Saxifraga 
Pennsylvanica, Caltha palustris, Viola blanda, Polygala sanguinea. 


Fic, 21.— Shallow, undrained swamp (peat bog) at Dune park. Jn the foreground 
the relict of the original pond, with water lilies; then in order, encroaching zones 0 
bulrushes, sedges, willows, and pin The hei in the background are on an estab- 
lished dune, and are not sisting on the swampy soil. 
Sphagnum occasionally occurs here, as it never does in the 
second type. Here again there is doubt as to the determining 
conditions, but it may be that things can be explained by the 
difference in the drainage. The ultimate fate of the second and 
third Swamp types is not known, The relative absence of trees 
and shrubs is certainly natural and in no wise due to man. 
