541 
eroded Wisconsin glaciated region. The horizontal or geographical suc- 
cession of associations in these depressions at present is important in 
showing the vertical or historical succession of associations during the 
gradual filling and draining of the sloughs since glacial times. Much 
of the Andropogon furcatus prairie of the state originated in this way. 
Mr. L. Wiles, of Dundas, Illinois, who plowed some of the virgin 
prairie in Vermilion county before artificial drainage was established, 
says that the only tillable soil between the rivers and sloughs was that 
covered by tall bluestem (Andropogon furcatus), and that usually the 
farmers were not able to plow quite all of the Andropogon prairie but 
had to leave a narrow strip of it surrounding other grasses bordering 
the sloughs in the depressions... In many places in the farming district 
these depressions have not yet been completely drained, and where graz- 
ing has not been too severe the successions of the native grasses are 
still evident. In some places, as in the depressions near Camp Grove and 
Lacon in Marshall county, all the associations up to and including Andro- 
pogon furcatus may be found, while in other depressions farming has 
destroyed the Andropogon, and sometimes Panicum, entirely. A sum- 
mary of these associations made from observations of more than twenty 
morainal depressions is given in Figure 5. 
Vestal (28) has described the associations about a small depression 
on the Valparaiso moraine on the boundary line of Cook and Dupage 
counties. While this prairie has some indications of the influence of 
civilization, such as the presence of red top and blue grass previously 
mentioned for the Chicago prairies, it is of interest as a description of a 
more xerophytic type of prairie characteristic of clay soils in the vicinity 
of forests. The hydrarch series is somewhat similar to that already 
described for the Chicago prairie, including the abundance of cultivated 
grasses and herbs. On the most xerophytic areas of the upland Andro- 
pogon scoparius is dominant. Silphium laciniatum occurs in patches as 
a local dominant. Several other coarse herbs are of frequent occurrence. 
The effect of grazing shown in Figure 5 is the same as that already 
discussed in connection with the flood-plain prairies. The conversion of 
natural prairie grass-lands to blue grass and red top by pasturing has oc- 
curred throughout the entire state. This fact is of interest both to 
the plant ecologist and to the farmers. In the first place the natural 
prairie grasses of any habitat serve as an indicator of the kind of culti- 
vated grasses most suitable for that habitat. This might be further 
extended to include all the agricultural crops of the region (Waller, 29, 
31). In the second place it points clearly to the best method of ob- 
taining permanent pastures. The data show that Kentucky blue grass 
is the dominant pasture grass of all the upland prairie region, and when 
once established it remains a permanent feature. On the other hand 
timothy and red top pastures are in general short-lived but have the 
advantage of establishing themselves more quickly. It is a well known 
fact that the blue-grass pasture sod can not be obtained the first season 
after seeding. This difficulty, however, is readily overcome by seeding 
