taking over shade garden
This looks like a type of beggarticks (Bidens sp.), possibly Bidens bipinnata. https://www.marylandbiodiversity.com/viewChecklist.php?genus=Bidens We would need to see photos of the flowers in order to confirm the ID.
Yes, it could be. There are no flowers yet. It's in a very shady area, so I'm not sure if it would get them. It's the first year I've seen them and they are growing a "mile a minute". I'll do my research to see if I keep or pull. I keep a lot of wildflowers, I'm very much a butterfly and bird person. So I'll look into it.
Thank you so much, I was going crazy...hemlock, parsnip, etc? It has a parsnip like stem, but I'd pulled some and no reaction to it, so I figured it was fairly safe. :-)
Sure, you are welcome.