Are the stems square in cross-section?

I was referring to the Boerhavia. I have had Ruellia for many years now, and know darn well it's Acanthus. I was thinking we called this already ? If not,sorry for the confusion, and I believe jeeksl is correct with Boerhavia erecta. And credit to Tiffany who first got the genus. It could also be coccinea, but I like the sound of erecta better. Actually, they both have a nice ring !

Yes, Late Boneset (Eupatorium serotinum), thanks!!!

Where I was coming from was that common snowberry as I have seen it in the western North American part of its range is polymorphic - and many times with shoots just like the low ones with lobed leaves shown and asked about in the original post here. Leaves on vigorous shoots are often lobed Burke Herbarium Image Collection (washington.edu)