CHICAGO AND VICINITY. 



•II 



type in sandy soil would not have a swamp developed. Morainic for- 

 est swamps are characterized by several trees, viz.: the bur oak, swamp 

 white oak, and scarlet oak {Quercus macrocarpa, Q. bicolor, and Q. coc- 

 cined), the red maple (^c^/- rubricni), the elm (Ulmus Americana), and 



the ash {Fraxi/ius Ameriiaiid). Other species are Cephalaiitliiis occiden- 

 talis (Buttorr bush), Salix discolor, Rihcs floridtim (Wild currant), Carda- 

 miiie rhomhoidca purpu?ca (Spring cress), Raiiuiiciilus septciifrio/ialis 



Fig. 23.— Pond at Waukegan almost destroyed by bulrushes. 



(Buttercup). This vegetation is ultimately supplanted by the mesophytic 

 forest. A vegetation allied with that of swamps is the amphibious ditch 

 flora with such plants as Nasfiirtium paliistre (Ditch cress), Peiithoriim se- 

 doides (Ditch stonecrop), Proserpinaca paliistris (Mermaid weed), Liid- 

 wigia pahistris, Polygonum Hydropiper (Water pepper), etc. 



Calumet lake and Grand Calumet river may be taken as types of 

 half-drained waters. We have here conditions that are midway between 

 those of peat bogs and those of ordinary rivers. The vegetation is sub- 

 ject neither to the currents of the rivers nor to thestagnant conditions 

 of the peaty lakes, and hence the luxuriance of the flora is far greater 

 than in either of the other instances. The aquatic vegetation is rich 

 both in species and individuals. Here is to be found a great wealth of 

 alga vegetation, including such forms as Cladophora, Spirogyra, Oedo- 

 gonium, Hydrodictyon. Among the floating plants are Riccia, Riccio- 

 carpus, the duckweeds (Spirodela, Lemna, and Wolffia). There are also 

 a large number of attached plants, including many species of Potamo- 



