Could it be a Pycnanthemum species? I say that because it looks just like the one I am growing in a pot at home.

Thanks texasflip. I found the residue and the leaves did have a minty smell. Those may be the winter leaves of Pycnanthemum albescens, which are apparently sometimes more rounded than the mid-season leaves. Nice catch!

Sure looks like Streptocarpella. But what would that be doing roadside in AR? Crazy thought, will be as curious as you, I LOVE purple leaves!

Cool, NM, sorry for blurting!