On Wednesday I was doing some work in one of our meadows and came across a sedge that looked a little odd to me - I was pretty sure that I had not seen it before so I plucked a culm and threw it in my bag.  When I keyed it out at the end of the day it easily went right to Carex bushii (Bush's sedge) a threatened species in Ohio 
Not happy with the result I looked in Vascular Plants of Ohio and in Gleason and Cronquist and found  that another species within this group exists in Ohio  but not in Michigan 
I decided to look in Vascular Flora of Illinois and not only were all three (C. bushii, C. hirsutella and C. caroliniana) included in the key but they are the last three listed in the Group 1 section (sedges with hairy parigynia, sheaths and/or leaves), here is the end of the key:
Leaves very sparsely hairy…………………………………………………..................................................................................................C. caroliniana
Leaves moderately to copiously hairy
Pistillate scales lanceolate, acuminate to awned, longer than the perigynia; perigynia rounded on all faces and strongly nerved………………………………......................................................................................................................................................................C. bushii
Pistillate scales ovate, acute to cuspidate, shorter than the perigynia; perigynia with flat, inner face, weakly nerved…………………………………………................................................................................................................................................C. hirsutella
Using the Illinois key I was satisfied that I had found C. bushii on Wednesday and C. caroliniana on Thursday.  I spent the rest of Thursday looking for the sedge that keyed so smoothly to C. bushii but I could find nothing but the sedge that I am now calling C. caroliniana.
Finally on Friday morning I retraced my path from Wednesday and located the sedge, once again it keyed very quickly to C. bushii.  Looking around I found examples of what I believe to be C. bushii, C. caroliniana, C. hirsutella and C. pallescens – here is a photo that I made of the four plants.
a comparison between C. bushii and C. caroliniana
and a close up of C. bushii
C.bushii seems to grow with culms that are spreading and at agles close to 45 degrees to the ground.
C. caroliniana culms are ascending with angles closer to 90 degrees.
 





