﻿1903] UPLAND PLANT SOCIETIES 45 



The Grand Rapids sand plain (reaching from Rockford, 

 through Plainfield and Grand Rapids to Grandville and Ross) is 

 generally covered with societies IV and V. The foundation soil 

 is apparently the same throughout, being a gravelly sand, but 

 the areas of society IV have undoubtedly more surface humus, 

 thus giving the soil a darker color and a more loamy texture. 

 The higher parts of the plain, and hence the portions which have 

 been out of water longest, are generally the portions which show 

 this condition. The lower portions where violent water action 

 probably continued after the main stream receded, and where, 

 owing to the slope, erosion is even now well marked, bear little 

 surface humus and are characterized by society V. Here, at the 

 time of clearing, the pine was usually present. Transition areas 

 between IV and V were covered with '*oak openings," however. 

 Much of these channel areas is swampy and hence thrown out 

 of the present discussion. 



North of Grand River it is only in the western column of 

 townships that the heavy clay is characteristically covered with 

 society I. In other portions of the region the clay is mainly 

 covered with society III, IV, or V. It will be noticed that clay 

 which bears the oak-pine-sassafras society is common in the 

 extreme north and becomes less common southward. Societies 

 III and IV approach each other in character as we pass north- 

 ward. The hickories become less frequent and the general 

 aspect of III becomes more that of IV. It needs to be remarked 

 here also that the stretch of society III, reaching from the 

 Rouge River southward and lying west of Grand Rapids, is a 

 curious mixture of II and IV. Judging from the trees alone, 

 the southern part of it should be placed in society II, but the 



J 



etc., seems to place 



it in the oak-hazel group. Sassafras is present here to a 

 remarkable extent, and in many places, especially to the north, 

 white pine also. The northern part of this stretch contains 

 much pine. Altogether, the area can better be classified under 

 III than otherwise. In the general discussion to follow the pos- 

 sible reasons for the mixing will be considered. 



In the bit of beech-maple society in the extreme north- 



