368 



Illinois Natural History Survey Bulletin 



Vol. 26, Art. 5 



grassy knobs were prairies on steep slopes, 

 or hill prairies. It is surprising that no 

 earlier descriptions of hill prairies are ex- 

 tant. Certainly the French settlers saw 

 the grassy slopes and perhaps named the 

 \illage of Prairie du Rocher (Prairie of 

 rlu- Rock) after the prairie above the cliffs. 

 The capable botanist, Andre Michaiix, 

 who traveled from Kaskaskia to Cahokia 

 and visited the village of Prairie du 

 Rocher in 1795, apparently made no rec- 

 ord, in that part of his journal included 

 by Sargent (1889), of grasslands on the 

 bluffs. Early gazetteers, as those of Peck 

 (18.54) and Ellsworth (1837), contain 

 references to w-et, dry, level, and undulat- 

 ing prairies, but apparently nothing about 

 prairies on the bluffs. Short (1845) 

 wrote a gcKnl description of the autumnal 

 aspect of flatland prairies; his journey did 

 not take him far enough to the west to 

 include hill prairies. 



Some references to hill prairies of Illi- 

 nois have appeared in the past 50 years. 

 Hus (1908) described the bluffs in the 

 vicinity of Collinsville and mentioned open 

 hillsides with grasses dominant and blue- 

 grass the chief species. \'estal (1918) 

 cited numerous prairie inclusions near 

 Charleston, described their topography, 

 and stated essential conditions for their 

 presence. Woodard (1924) mentioned 

 prairies on bluff-ridges. Vestal (1931) 

 reported the occurrence of prairies on 

 loess bluff's of the Mississippi River, and 

 Vestal 5: Bartholomew (1941) brieHy 

 described some prairies on the loess bluffs 

 of the Illinois River. 



These authors were concerned only 

 with local occurrences of hill prairies in 

 Illinois. The> did not report on the ex- 

 tent of hill prairies in the state, nor did 

 they report in detail on the flora of the 

 hill prairies, the characteristic plants, 

 relative abundance, presence and space 

 relations as determinable in plot studies, 

 or the origin and history of hill prairies. 

 In order to obtain the necessary infor- 

 mation for a study of these characteristics 

 of hill prairies and for a description of 

 hill prairie vegetation in Illinois, the 

 writer made numerous plant collections 

 and plant identifications from 61 hill prai- 

 ries, fig. 1, having a combined area of more 

 than 200 acres. Detailed data pertaining to 



the vegetation were obtained from two 

 prairies by use of plot studies, as explained 

 in a later section of this paper. 



The locations of some hill prairies were 

 determined by the writer from the field 

 notes made by Dr. Vestal during his trav- 

 els in the state; of others, as the prairie 

 southeast of Menominee Station in Jo 

 Daviess County, from a study of aerial 

 photographs. The majority, however, 

 were found by field reconnaissance of the 

 writer. During late autumn and early 

 spring, hill prairies can easily be seen 

 from tlie roads near or at the bases of the 

 bluffs. Sucli roads, called bluff roads on 

 some maps, are common in both the Mis- 

 sissippi and Illinois river valleys. In the 

 Mississippi River valley, bluff roads were 

 traveled by the author from Olive Branch 

 in Alexander County northward to a 

 point north and west of Glen Carbon in 

 Madison County and from Hamburg in 

 Calhoun County the 275-mile distance to 

 the northwest corner of the state, except 

 for short gaps in Hancock, Henderson, 

 Mercer, Rock Island, and Jo Daviess 

 counties. In the lower Illinois River val- 

 ley, bluff roads were traveled from Graf- 

 ton to Hennepin, except for a few gaps 

 in Mason and Tazewell counties. The lo- 

 cations of prairie sites were marked on 

 maps of sufficient scale to be used easily. 



Not all hill prairies seen w-ere visited, 

 nor were bluffs of small streams exam- 

 ined for occurrences of hill prairies. 

 Doubtless small prairie openings occur on 

 the bluffs of small streams in the western 

 part of the state. In eastern Illinois, Ves- 

 tal (1918) observed several prairie open- 

 ings along the Embarrass River near 

 Charleston. 



ACKNOWLEDGMENTS 



It is indeed a pleasure to acknowledge 

 the assistance given by Dr. A. G. Vestal, 

 Department of Botany, University of Illi- 

 nois, in the preparation of this study- I 

 wish to thank him for his willingness to 

 direct this investigation and for the many 

 helpful suggestions he made during its 

 progress. 



Dr. L. R. Tehon, now deceased, and 

 Dr. H. B. Mills, of the Natural History 

 Survey, greatly facilitated the progress of 



