That's odd. It wouldn't let me post a picture. The t-posts in the background are 5 feet tall. These are huge. I'll see if the website will let me post a close up of the flower.

If you think it has features of a gaura then this might be relevant:

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC3881414/

Wow thats a tight bunch of flowers, but otherwise, it does look like a gaura to me.

If we had any idea of what part of country you are in, or if this is naturally occuring, it would probably help.

These were at a state park in central Texas. I can't remember which park it was though.

Looks just like it:

https://www.bing.com/images/search?q=stenosiphon&id=120A830071A40A0A33A1038B284C5383BA44EF70&FORM=IQFRBA

They do! Thank you jekeesl and Embothrium!

Jane, my pleasure. You took the time to get good photos, plus provided location and specimen size which made the ID pretty easy.