214 ILLINOIS STATE ACADEMY OF SCIENCE 



BOGS OF NORTHERN ILLINOIS— II 



W. Gr. Waterman, Northwestern University. 



At the 1921 meeting of this academy the writer briefly 

 described four bogs located in Lake County, Illinois, and 

 mentioned several others which had been heard of or seen 

 in the distance, but not visited. In the present paper 

 five others are described and some data are added to the 

 descriptions already reported. There is still certainly 

 one and possibly several others which have not yet been 

 visited. (Fig. 1.) 



The new bogs, both those visited and those reported, 

 are in the same general region, already described. That 

 is, they are all within the limits of the late Wisconsin 

 Drift of the Valparaiso moraine which is characterized 

 by a soil consisting of clay or gravel, frequently con- 

 taining a large percentage of calcium carbonate, and 

 having an uneven topography, orginally with many knobs 

 and kettle holes. Most of these depressions have been in- 

 cluded in the drainage systems of the rivers of the region, 

 but a section in western Lake and eastern McHenry 

 Counties on the edges of the drainage basin of the Fox 

 and DesPlaines Rivers still contain a few poorly drained 

 or undrained depressions, and it is in these that the bogs 

 are found. 



For a thorough understanding of these formations at- 

 tention should be called first to the present distinction 

 between bog and swamp, which is based partly on the 

 character of the habitat and partly on floristic content. 

 A bog is characterized in general by a xerophytic vegeta- 

 tion and by the presence of such special forms as the 

 pitcher plant, drosera, cranberry and sphagnum, which 

 are accompanied usually by an acid condition of the sub- 

 stratum. In a swamp, on the other hand, the characteris- 

 tic bog plants are absent and the substratum is alkaline 

 or neutral. There are, to be sure, occasional anomalous 

 communities in which a few bog species are present, al- 

 though the conditions in general would seem to indicate 

 a swamp. In the main, however, the distinction is fairly 

 well marked, and in many cases it is so w T ell defined that 



