We see it along the roadside way up in a dampish spot in the shade. It doesn't do extended periods of hot and dry because two very hot and dry days after I took these pics, the plants were completely wilted and done.
Poor things.
The flowers are pink and very small. Mostly you just notice the longer
spikes of spent calyxes. For a long time, seeing this through the
windows of a moving car, I just thought they were green flowers. It is Perilla frutescens. Chinese basil. It took me a long time to find a good online reference about it because often perilla is a bit taller, with curlier purple leaves. [The curly leaves are called 'crisped'.] As in, purple like coleus purple. Or purple basil purple. Purple.
And this one was definitely not purple, except the stem. So this one confused me.
That purple variety grows way back in our iris bog, and seems to come on a bit earlier. Now that I know they're related, I'll keep a better eye out and try to get some pics of them together.
These are super easy to grow from seed and they will Take Over if you let them. Ours in the iris bog is competing with the mint and iris - pretty fierce competitors - so it hasn't taken everything over. These along the road are competing with the county bush hog, the clover, wood nettles and poison ivy. It's holding its own.