Our garden is a little "wild" looking, so I tend to let unidentified plants go a while to make sure I'm not pulling something I planted and forgot about. Unfortunately, this thing took hold and I can't get rid of it. The roots are shallow and it's relatively easy to pull, but no amount to pulling seems to eliminate this plant. I'm about ready to sacrifice the seedlings I DO want in this area (Coreopsis, Echinacea, and Hollyhock) and spray the area, but I'd love to avoid that loss. Is this some perennial I've introduced at some point that I'm not leaving long enough? (I pull them when they reach 6"-12" tall) Can anyone tell me what it is and how to eliminate it? I'll keep pulling if that will eventually solve the problem, but it's really taking over a 6'x30' section of my garden.