PAPERS ON BOTANY 237 



on the end of the Calnmet ridge at the Wihnette harbor. 

 On the sandy beach in Evanston, Populus balsamifera 

 grows abundantly. 



In many places in the Evanston-TVinnetka area large 

 spruces, firs and Xoi^ray pines have been introduced. 

 One large hemlock (Tsuga canadensis) was found on the 

 Glenwood bluff north of Elm Street, Winnetka. These 

 species are not natural here, their ranges ending farther 

 north. 



TVest of the Kose Hill bar, between it and the swamp 

 forest is an unforested area which is now occupied by 

 the Xorth Shore Drainage Channel. The natural vege- 

 tation has been almost entirely destroyed, but was prob- 

 ably similar to that of the swampy tracts west of the C. 

 and X. "W. Ey. in Eogers Park. East of the ridge is a 

 similar but smaller and more irregular depression which 

 continues itself in the "Campus Meadow" of Xorth- 

 western University and the unforested swale between 

 Sheridan Eoad and Sherman Avenue, south of Colfax 

 Street. This is a part of the old swamp mentioned by 

 Miss TTillard and Miss Childs. 



CONCLUSIONS 



The distribution and character of the areas of the 

 three different associations at the present time are such 

 as to suggest that the original forest probably covered 

 practically the whole of the region studied, with the ex- 

 ception of the depression west of the Calumet ridge and 

 that between Sherman Avenue and Sheridan Eoad. The 

 outline of this forest was probably irregular extending 

 into the marshy tracts where the ground rose liigh enough 

 for the forest trees to live. 



This forest was not divided into distinct associations 

 set oft" by definite lines from each other but was appar- 

 ently composite, consisting of mesophytic forest on the 

 upland with a gradual transition to the xerophytic for- 

 est on the ridges and the swamp forest on the lowland 

 plain. The swamp forest itself was more or less hetero- 

 geneous, api^roaching the xerophytic type on the higher 

 ground and maintaining an almost hydrophytic vege- 

 tation in the lower spots. 



