Hi. This is my first post. My husband and I built a house last year on a lot that had been overgrown for decades. We are battling the usual brambles and such, along with Japanese Knotweed and garlic mustard.

This weed is one I can't identify. I originally thought it was some sort of weedy groundcover, because it came in low and spread in clumps. It grows equally well in lawn or bare ground, full sun or mostly shade.

However now it is getting taller...and taller...and taller. It seems only moderately affected by weedkiller. Pull it out and it comes back, dig it up and it comes back. Perhaps if I identify it, I can figure out how to beat it.

Three pictures: the plant as it grows in clumps, a single plant, and a single stem with leaves:

Thanks!!