Somehow or other, some kind of betony has showed up in my yard in a planter of ornamental oregano. It's attractive and I don't mind it being there....but I didn't plant it. ;-)

Now, it's not all that strange, since some kinds of betony are considered medicinal herbs and it's in a planter with other herbs (although those herbs have been in that planter for at least two years, and the betony only showed up this spring). But I'm wondering -- is betony (Stachys) a known invader around here? This is definitely NOT Stachys floridana, which is the only species I could find referred to as an exotic invader on a very quick search. I haven't ID'd the precise species, but it's one of the Stachys with crinkled non-fuzzy leaves and purple flowers.

Any input would be welcomed!