Gaura sinuata or Gaura sinuosa ?

I think it's called Oenothera sinuosa now. I'm thinking I encountered it later in the day when the flower petals were ragged and that threw me off. but I was thinking it reminded me of Gaura the whole time. The foliage is badly eaten, but still had that evening primrose look. There is no listing for Gaura on bonap tho I thought maybe there were a couple species not reclassified. (?) The strange thing is that according to bonap Oenothera sinuosa isn't native to Illinois, but it is in Missouri. The internet pictures look close. This was growing at the Midewin National Tallgrass Prairie. They will know for sure what it is. Thanks Carol!

All of Gaura was lumped into Oenothera, if I recall. Oenothera gaura is native to your area and is similar...