Looks like some species of Smilax, or greenbriar, of which there are many. I had a thorny variety, Smilax hispida, that took years of digging and spraying to eradicate. Good luck!

OOPS. I take it back. The leaf looks right but Smilax is alternately leaved, not opposite. Sorry.

If not smilax, perhaps Houttuynia.

Could you post a photo of the tops of the leaves?

I was thinking honeysuckle until you described the seed pods.

So, not honeysuckle, but back in the early days when you let it vine, did it flower before setting those seed pods? Can you remember anything about the flower?

Whatever it is, you have my best wishes for eradication, or at least some sort of truce.

I went looking down the alleyway and found some buds (too early for flowers yet) right next door where it's about three feet tall now. :-( Unfortunately I don't remember what the flowers looked like, other than that they weren't gigantic.

This is a picture of the same weed, but a very mature version, quite a few years old and covering a fence, that I found a few alleys over. The leaves look quite different.

Found it!

The older leaves looked so much like morning glory, and I knew that couldn't be right, that I did a Google search and found the seed pods under lookalikes. It is Honeyvine Milkweed, and I have my work cut out for me. Any advice is appreciated.

Your final picture isn't the same plant. The leaf shape and arrangement (alternate, not opposite like your first plant) are entirely different. It looks like Bindweed, Calystygia sepium. A perennial which comes up from the roots every year and another very hard to eradicate plant.

You are correct, floral - thanks! I still think my identification is correct, however, as Honeyvine Milkweed, which has opposite leaves.

You have the genus right, Cynanchum, but the plant in your pictures is either black swallowwort (Cynanchum louiseae) or European swallowwort (C. rossicum). Both are highly invasive. Cynanchum laeve is a native species that doesn't occur in Michigan and usually doesn't persist where it has been introduced outside its native range, plus it has whitish flowers.

I agree with lycopus.

Mine, which is identical to what you described and pictured (in the first one, and possibly the third one, anyway) is definitely Cynanchum louiseae (aka Black swallow-wort, Louise's swallow-wort or Black dog-strangling vine).

I'm currently researching how to get rid of it as well.

Kat

Yes, lycopus was right. I learn so much more all the time about plant identification, and love the wisdom of this community. I waited for flowers (plentiful down the alleyway and in neighbor's yards, where I'm not allowed to pull them) and confirmed it. It is definitely black swallowwort, not honeyvine milkweed. I contacted my state's invasive species office, but they don't seem impressed. Every yard and field around here has it, so I think my battle will continue. So far I am still stuck with pulling it up (over and over and over and over and. . .) ;-)

Hi LilyD74,

I spent about 1.5 hours yesterday digging out the roots in a patch about 30cm x 30cm (I think that's about 1 x 1 ft). I probably came up with about 4 cups of roots! It's all through the rest of the bed, but i figure I'll test that area and being so aggressive with it and see how fast it comes back. If it slows it significantly I'll get that aggressive (as I can - of course it's all through a bunch of perennials) with the rest of the bed. If it basically doesn't do much, i'll just keep pulling the stems. Good luck with your battle!