August, 1955 



EvERs: HiLi, Prairies of Illinois 



443 



(i.e., uf much lower presence in other 

 prairie types in lUinois) were Bouteloua 

 curtipendula, Psoralen tenuiflora, Peteilo- 

 stennim ctinditlitni, Linutii sulcatum, and 

 Lithospennuiii inciuitn. 



14. Prairie stands possibly existed on the 

 bluffs that now support prairie from Wis- 

 consin or pre-Wisconsin time to the pres- 

 ent. This vegetation will presumably con- 

 tinue to grow on these sites until a change 

 in climate occurs which will provide more 

 iiiesic conditions, or until advanced erosion 

 of the bluffs forms a continuously gentle 

 slope, or until high cliffs are reduced. 



15. The observed flora of Illinois hill 

 prairie was 394 species and varieties. Of 

 these, 390 were vascular plants distributed 

 in 209 genera and 70 families. The larg- 

 est family was Compositae, with 26 gen- 



era and 71 species and varieties. Aster was 

 the largest'genus, with 12 species. Thirty 

 species were of foreign origin. 



16. Although most species of Illinois 

 hill prairie plants are of southeastern ori- 

 gin, nine species are distinctly western or 

 southwestern, and three are from the 

 Ozark plateau. Of these 12 species, Alent- 

 zeliii olujosperina, Asclepias stenophylla, 

 and Rudbeckia missouriensis are seemingly 

 restricted to hill prairie and adjacent rock 

 ledges. 



17. Some prairie slopes are grazed, and 

 some are annually or less frequently 

 burned, yet the prairie persists. As these 

 steep slopes have never been plowed, they 

 represent one of the least disturbed types 

 of prairie in Illinois, and some of them 

 should be preserved. 



