August, 1955 



EvERs: Hill Prairies of Illinois 



379 



more or less slumping of loess and, as a 

 consequence, possessed sizable areas with- 

 out plant cover. The more gentle slopes 

 near the bases of the prairies had less se- 

 verely eroded surfaces, and consequently 

 more plant cover, than the steep spur 

 fronts, but they contained more species 

 characteristic of rock ledges. 



Sizes and Shapes oi Study Plots. — A 

 ^'-milacre square was staked on the upper 



slope of a spur of each of the prairies, 

 Phegley aryl Sampson. These plots were 

 located at some distance from the crest of 

 the bluff in an attempt to exclude forest 

 plants and pasture weeds. Each 9-milacre 

 square was then divided into nine 1 -mil- 

 acre quadrats (0.001 acre or 4.046 square 

 meters). The central milacre of the 9- 

 milacre grid was selected for mapping. 

 Each central milacre was divided into 



UPHILL 



Fi^. 9. — A 1-milacre quadrat in the unpastured Sampson hill prairie, charted October 15 

 and 16. 1951, by R. A. Evers. A. Andropogon scoparius\ Li, Lecidea spp. ; H. Houstonia nigri- 

 cans: D, Desmodium ciliare; S. SoUdago nemoralis; B, Bouteloua curiipendula; G, Gerardia 

 sp. ; P, Petaloslemum purpurtum\ F, Andropogon gerardi; L. Lespfdeza capitata; Av, Agavt 

 ^-irginica: E, Euphorbia corollata; Op, Opuntia rafinesquii. 



