232 ILLINOIS ACADEMY OF SCIENCE 



who says that at about 1865 the part of Evanston north 

 of Church Street and west of Chicago Avenue was a 

 marsh standing partially under water for several months 

 of the year. This tract, she says, was later drained and 

 made habitable by her father. In describing Evanston 

 at the founding of Northwestern University, Mar^'- Louise 

 Childs (4) also speaks of this swamp and says that practi- 

 cally all of Evanston was a swamp with a few groves of 

 oaks and maples on the higher ground. Such a patch is 

 that now included in the XorthAvestern University cam- 

 pus. These swamp conditions extended to the bluff at 

 Winnetka and the present towns of Evanston, Wilmette 

 and Kenilworth would have been impossible without ar- 

 tificial drainage. 



Investigation 



a. associations 



A large part of this region is still covered by an ex- 

 tensive forest which may be divided into three distinct 

 associations, characterized by the predominance of cer- 

 tain tree species and by the accompanying undergro"\^i;h ; 

 the upland oak-hickory, a more or less xerophytic sand 

 ridge type and the morainic swamp forest. The asso- 

 ciations of the Chicago Region have been described by 

 Cowles (5) and his classification is followed here. 



No great attempt has been made to differentiate be- 

 tween the types of red oaks, Quercus rubra, Q. Velutina 

 and Q. ellipsoidalis, for, as it has been said, it is very 

 difficult to distinguish the species. In general, Quercus 

 velutina (Q. coccinea-tinctoria of Cowles) seems to occur 

 very sparingly, while Q. rubra and Q. ellipsoidalis are 

 found in all the associations in varying proportions. Q. 

 coccinia, mentioned by Cowles as a member of the swamp 

 forest, is not found in this region. 



The upland oak-hickory association on the moraine 

 west of the Glenwood beach, is composed chiefly of the 

 white and bur oaks (Quercus alba and Q. macrocarpa, 

 with a small proportion of red oaks, hickories (Carya 

 ovata) and a few scattered black cherries (Prunus 



