THE VEGETATION OF THE CHICAGO REGION 



In this outline no attempt is made to treat exhaustively either the 

 plant associations or the list of species composing them. Only the 

 clearly defined associations easily accessible from the city of Chicago are 

 included, more particular attention being given to those peculiar to 

 this region. The names of weeds or ruderal plants are not included in 

 the lists. For more detailed studies of these plant associations see 

 CowLES, The plant societies of Chicago and vicinity, Geographic 

 Soc. of Chicago, Bull. 2. 1901, and for the plants of the vernal flora see 

 CowLES and Coulter, A flora for high schools, pp. 144. ill. New York: 

 Amer. Book Co., 191 5. 



I. THE SAND DUNE AND UPLAND ASSOCIATIONS 



The following paragraphs outline the well-marked succession of 

 plant associations upon the sand dunes of the Lake Michigan shores 

 near Chicago and include several of the more typical associations of the 

 forested morainic uplands. Following the outline is a list of many of 

 the characteristic plants of these associations, the name of each species 

 being preceded by a number or by numbers corresponding to those of 

 the association or associations in which it chiefly occurs. For details 

 regarding the vegetation of the sand dunes see Cowles, Bot. Gaz. 

 27:95ff. 1899. For evaporation and soil moisture conditions see 

 Fuller, Bot. Gaz. 58:193-234. 1914. 



1. The beach association. — The vegetation of the beach is scanty, 

 consisting principally of xerophytic annuals together with a few peren- 

 nial herbs and shrubs. 



2. The fore-dune associations. — This region of embryonic dunes 

 is characterized by the sand reed grasses and such shrubs as the willow 

 and the sand cherry together with the herbaceous plants of the beach. 

 Well-developed fore-dunes may be seen at Lake Bluff, 111., Miller and 

 Dune Park, Ind., and Sawyer, Mich. 



3. The Cottonwood association. — This is notably the area of actively 

 moving dunes with sparse vegetation. The rate of evaporation is very 

 high, but the water content of the soil remains very constant at a short 



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