Common has pink flowers. Looks like dogbane to me.

Here is a link that might be useful: Milkweed Guide

It looks different from my common milkweed. Those leaves
look thinner. Maybe there's more than one kind of common
milkweed. Remember it's invasive.

{{gwi:493468}}

It's definitely Dogbane. Check out KC's link. The flowers are not Asclepia flowers. This is an easy mistake to make as the leaves are so similar to milkweed, and there is milky sap. Don't feed any part of this plant to Monarchs as they will die. I know, I've made this mistake!

Sandy

I have frass on two of these plants, plus two larvae, although I was not sure they were mb cats, didn't look quite right. So maybe the mbs laid on the dogbane, the cats hatch out, eat the stuff and die? Bummer. Looks I have some pulling to do.....

Definitely Dogbane. Don't be too hasty to pull it out yet. It is an excellent nectar flower. However, it does spread rapidly. So, maybe you do want to remove it. We fight this plant all the time in our butterfly house.
Cheers,
Elisabeth

I asked this very question just a little while ago. I have a big area of it and was hoping it was swamp milkweed.....but its dogbane.
I'm thinking what gives it away is the reddish stems.

Dogbane before it blooms is a very close double to milkweed. However, I've learned to differentiate it from our local viridis by the fact that viridis sprawls close to the ground and the Dogbane is erect. Both have red stems which are hollow when cut or snapped, and white sap.