I have not been able to positively ID this annoying plant. Some suggested it belongs in the nettle family, but it is not irritating, so I'm not sure. I produces these ugly tiny flowers which grow very close to the main stem. Seems to thrive in moist soil and it is easy to remove. It's just that I spend an awful lot of time removing the darn things!
I usually remove them as soon as I see them but I am letting one grow in a concrete crack (yes they'll thrive anywhere!) to see what it looks like at maturity. So far it is about under 12" tall. It doesn't die back in winter but it may slow down a bit, unless it rains.
TIA for your help
