Black Swallowwort is Invading Cambridge - And It Might Be Coming to Your Town Too

My nemesis - black swallowwort - is invading Cambridge. I've been out and about in the last few days and found big patches of it in many, many front yards in Cambridge. And no question about it - it's in Somerville, Medford, and Arlington too. In fact, it's becoming an issue all over Massachusetts. It could very well be in your area too - black swallowwort has spread across much of the United States.

Black swallowwort looks a bit like milkweed. But instead of the fuzzy, lumpy pods of regular milkweed the swallowwort seed pods are thinner and smooth, shiny green. It's a rapidly growing vine and if allowed to flourish will produce numerous pods. Last summer I would find large stands of swallow-wort covering chain link fences and dripping with pods. Unfortunately I think some people actually like it since it does do a good job of covering up those chain link fences.

I found black swallowwort in my yard a couple of years ago but didn't know what it was at the time. But it was growing so fast - twining around other plants, sprouting up everywhere I looked - that I searched online for it. I was horrified by what I read. Search for it online and you'll be ready for all out war after you learn more about it.

Black swallowwort is extremely invasive. It will push out other vegetation and is hard to eradicate. Like regular milkweed, the seeds from pods that are allowed to remain on the vines will spread all over the neighborhood. Your neighbor's swallowwort is your problem too. Let it thrive and soon it will be all over the neighborhood pushing out other plants. It can quickly become the dominant plant in a landscape and will push out other plants and wildflowers.

Swallowwort is not only a threat to vegetation. It is also believed to threaten the viability of monarch butterflies. Monarchs lay their eggs on milkweed and are thought to mistake swallowwort for milkweed. Caterpillars hatched on swallow-wort do not survive however. Areas infested with swallowwort also have fewer nesting birds and insects. By pushing out native vegetation black swallowwort has a significant impact on the food chain.

The first year I found this invader in my yard I made the mistake of breaking off the vines but leaving them to wither with the pods still attached. Unfortunately, even if the vine is dead, the pods will still eventually release their seeds. The pods must be removed and disposed of carefully - I wrapped them up in foil or tightly closed bags. Some recommend burning.

Last year I went on an anti-swallowwort crusade. Anywhere I went I would pull off pods and filled bags with them. I listed a house for sale in Cambridge that had black swallowwort climbing everywhere in the garden. I filled more than one large trash bag with the vines. Once I started to look I found it everywhere - all over Cambridge, Somerville, Medford and Arlington.

I'll post more photos of swallow-wort as it matures. The picture taken above was taken in Cambridge in mid-May. Right now the pods aren't out but the flowers are on the vine. The flowers look like small purple stars. The leaves are spade shaped and shiny green - sort of like lilac leaves but shinier. The way the vine will curl around whatever it comes in contact with is very distinctive.

If you see pods when you're out and about - pick them and dispose of them. Once the pods start appearing I carry plastic newspaper bags with me and fill them with pods I come across.

If you discover swallowwort in your yard the only effective method of eradication is repeated sprayings of herbicide. Pulling the vines will not work - there is a large underground network of roots and you can't stay ahead of it by pulling it. Even people who garden organically find no other adequate method to rid their garden of this super pest. Get an industrial sized bottle of herbicide and get ready to do battle.

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Elizabeth Bolton is a real estate agent with the Huron Avenue office of Coldwell Banker in Cambridge, MA.

A version of this article, Black Swallowwort is Invading Cambridge, was first published on http://centersandsquares.com.