2o8 BOTANICAL GAZETTE [September 



more meso 



(Q. rubra and Q. alba) and one or two species of Carya, eventually 

 giving rise to a fairly mesophytic association, commonly desig- 

 nated the oak-hickory forest. Although rather abundant in the 



seem 



com 



as it has 



been excellently described by Cowles (9). Similar 



sufficient for very brief descriptions of the other associations 

 included within the scope of this paper. 



The most accessible, comparatively undisturbed area of this 

 association near the city of Chicago is found about 15 miles 

 southwest of Miller, Indiana, at Palos Park, Illinois, where it has 

 developed upon morainic clav. Here stations 12, 11, and 14 were 



my students, Mr. Wade 



mes 



com 



most 



respects to a floodplain. In the depression there 

 were, in addition to the trees of the upland, such typically flood- 

 plain species as the white ash (Fraxinus americana), the elm (Ultnus 

 arnericana), and the black walnut (Juglans nigra). A more de- 

 tailed description of the forest and an analysis of the results of 

 191 1 have already appeared (10). In this year there was an aver- 

 age midsummer maximum rate of 17.5 cc. per day (fig. 5) from 

 stations 12, 13, and 14; a minimum rate of 2 . 7 cc. ; and an average 

 for the season of 180 days of 9.8 cc. per day. In 1912 the mid- 

 summer maximum was 10 cc. dailv (fig. 6) . the minimum the same 



preceding year, while the 



mes 



floodplain forest of the depression, we find 

 maximum of 16. 2 cc. daily in 191 1, a minin 

 average of 8.3 cc. daily (10). In 191 2 the 



maximum 



educed 



minimum 



only 4.2 cc. daily (fig. 10). 



m 



:h (Fagus grandifolia) 

 nous members. The 

 attain this climax, a 



