HELP! What is it?

This plant has appeared in my perennial garden this spring and I do not believe it's one that I planted. It has very strong, ropey red runners. If it's an invader, I need to act fast! Do you know what it is?

ropey runners remind me of goldenrod in my garden at least.

Can you tell me more about goldenrod? That's been suggested.

Probably all of the Solidago that I am familiar with has leaf margins that have teeth of some sort. The leaves on the plants above look entire (smooth). Not that my vision is all the greatest but they don't appear to have any teeth.

Solidago is a native plant but too much of a good thing is too much of a good thing and I'd probably remove at least some of it as soon as you are able to determine if it is Solidago or not.

It would probably be a good if you could post more photos with some close ups of the leaves. Once the plant blooms you might want to share some photos of the flowers too. I'd leave it be until you get a positive id.