These seedlings started appearing this past spring. I left a few to see what they turned out to be. But they just kept popping up. Everywhere. I decided whatever they were, they were much too invasive to keep; so I pulled everyone I found.
Now I'm curious again. There are a few here and there, but none large enough to bloom. The seed leaves look familiar to me, but I can't place them. The vine is not familiar.
Seed leaves:
The seed leaves are rather distinctive. Three other clues: 1) The true leaves are heart-shaped, 2) the leaves are gray/glaucous, and 3) the vine attaches by tendrils, it does not twine.
Vines:
Interestingly, the vines are growing rather slowly, not aggressive and rampant as I would have expected.