invasive species

There was a lot more interest than I would have expected in my brief mention of my problem figuring out what to do with five bags of garlic mustard. The update is that I put off dealing with the problem while I finished grading, and then the bags started to leak. Most of it turned into a disgusting slime. I spread the mess out on the patio to dry. Of course it started raining an hour later. At least the rain washed off a lot of the slime. In the past two days, I picked out more second year garlic mustard that had been hiding among the violets, and realized there is a carpet of first year plants to dig out. I think I’ll be spending much of my sabbatical doing this.

You may think that weeding means I’m gardener. Nope. I have a brown thumb. The only gardening activities I am good at are destructive: mowing, weeding, and digging up bushes that are blocking the walk. Everything I’ve planted or paid someone else to plant has turned out to be a mistake: it either died or proved to be the wrong plant in the wrong place. We have the scrappiest yard on the block. My spouse thinks that if you mow your lawn you have done all that anyone can expect of you in the way of gardening, except for extreme cases that call for nuclear herbicide. We both would prefer a natural yard that looks like an unkempt woodland edge and needs no maintenance, but it turns out that neglecting your yard does not produce a natural woodland. Yard neglect creates a safe haven for invasive species.

Garlic mustard is so aggressive that it is choking out the violets that we have been encouraging by not mowing them. Violets are also an invasive species, although, as my mother-in-law said, they invade slowly and are pretty. Also invasive are the dandelions that are billowing in our yard and about half the yards on my block – they were introduced into New England by early European colonists. Opinions are divided about dandelion beauty. Only herbicide will keep dandelions out of your lawn, and my environmentally-conscious city has become increasingly dandelion-tolerant and herbicide-intolerant. You can tell I live in a relatively conservative part of town because half the yards are dandelion-free. Dandelion and garlic mustard greens are good in salads, which is why they are in North America – they escaped from salad gardens. But I have much more of both in my yard than I am willing or able to eat. I can’t find the history of violets, but in trying to find it, I’ve learned that there are a LOT of kinds of violets. The sweet violet is listed as invasive in my state; the picture looks like what is in my yard, but, to be honest, violets all look pretty much alike to me.

There’s a new tall plant with fragrant purple flowers that turns out to be dame’s rocket. It took me several hours of frustrating Internet research but I finally found it in the “What’s Blooming” section of the botany department’s site. Here’s what it says on the university extension’s horticulture site (which I could only find by googling “dames rocket” as the direct link is buried deep in a list of “fact sheets”):

Dame’s Rocket, Sweet Rocket, or Dame’s Violet (Hesperis matronalis) is an attractive, but invasive plant. A common garden flower introduced to America from Europe in colonial times, it is invading Wisconsin woodlands and has the potential to become ecologically devastating to native plant species. Dame’s rocket is listed as a noxious weed by the United States Department of Agriculture. This weed in the mustard family has many similarities with garlic mustard, a related plant that has inundated woodlands in southern and eastern Wisconsin in recent years. Dame’s rocket has been around Wisconsin for many years, but seems to be showing up in more and more sites all the time. It is now at a relatively early stage of encroachment.


I spent last summer digging up the underground runners from some invasive tree species that was sprouting up all over the back yard. If you mowed them down, more would grow back to a foot or two high within a week. No kidding! It was like being mobbed by a gang of child trees. I think I got it all out, but as my spouse says, the yard now looks like it was attacked by a deranged mole. I thought at the time it was rebounds from the buckthorn we had to attack with Roundup* a couple of years ago, but now I think they must have been black locust, which is native to the Appalachians and Ozarks but invasive in Wisconsin. The black locusts were planted by one of the untalented landscapers I employed, who sold us trees that had something else grafted onto black locust bases. The something else was a kind of “bad tree” whose branches spontaneously broke off; all three had to be removed, the last after it fell over onto the house. Apparently once a mother black locust tree is hurt, new trees sprout rapidly from lateral roots. So now I’m worried that the other little trees I thought were OK are actually buckthorn. Well at least I found the buckthorn fact sheet: orange inside the bark seems to be the mark of the devil.

Our yard also has ragweed, goldenrod, thistle, stinging nettle, lily of the valley – all listed as noxious, invasive, or both – and dozens of other plants whose names, pedigrees and community-spiritedness I have no clue about. However, I’m beginning to see a pattern: all the plants that will grow in your yard without much trouble are invasive. The green grass that is supposedly the mainstay of our lawn is also an invasive plant, although one that certain city regulations require me to nurture rather than attack. The only way to get a “natural” yard is to work at it.

There are lots of invasive species, and if you start reading about it, it’s kind of like the invading aliens in the War of the Worlds. Plants on the march. Not to mention bugs and fish. Check out some lists here and here and here and here. These and many more organizations are opposed to these militant plants and urge us to take up arms against the invaders. A whole new social movement I knew nothing about. I cannot help but reflect on the irony of this. The descendants of the Europeans whose invasion killed (mostly through disease) the Native American people are now trying to protect the Native American plants from the European plants they brought with them.

All of this leads to a lot of reflection while weeding. If you are as untalented and ignorant of gardening and plants as I am, choices about what stays and what goes are wildly haphazard and easily influenced by all sorts of ever-shifting criteria. But if you think about it enough, all the choices about what to cultivate and what to eradicate (or try to cultivate and try to eradicate) seem rather arbitrary. Humans are the quintessential invasive species. We dominate and modify ecosystems wherever we go. I’m doing it myself as I make my uninformed choices about weeding, but so did the neolithic farmers and the “hunter gatherers” in pre-Columbian America.** In fact, all species modify their environments: elephants, beavers, giraffes, termites, ants, bees, and anaerobic bacteria all come to mind as cases I know about.

There is a lot of recent scholarship, about which I know only a little, that challenges the whole concept of the “natural” environment, arguing that humans and other species have always intentionally shaped their environments. This is not a license to throw toxic waste into a watershed or to ignore greenhouse effects. Historical biology teaches us that humans and other species can make their own environments uninhabitable even for themselves, not to mention others. Rather, if there is no “natural’ environment that will happen through simple neglect or inaction, we have to take positive responsibility for attending to the environmental impacts of our actions. But this is no easy matter. I’m still not sure what to do in my yard, except that it is clear that if I want to keep the violets, I have to beat off the invading horde of garlic mustard.

*Roundup is the nuclear herbicide, a scorched earth approach. We used RoundUp to go after the buckthorn because there was no other way to get rid of it. But RoundUp also killed the nearby sumac and dogwood even though we tried to apply it selectively. It is accused of toxicity to animals; it is certainly toxic for all but RoundUp-resistant plants. Monsanto’s web page and anti-Roundup toxicity site.

**A fascinating book that gives a popular summary of the research challenging the view that Native Americans left their environment untouched is 1491 by Charles C. Mann. Mann provides citations to the geographers who challenge the idea of the natural environment. In addition to developing the argument that the North American woodlands and the Amazon rain forest were both created by intentional human cultivation, Mann also discusses the importance of depopulation and intra-American politics. Mann is a journalist who reads and summarizes academic research and gives some attention to the history of relevant academic debates. One of the best books I’ve read this year.

Author: olderwoman

I'm a sociology professor but not only a sociology professor. I keep my name out of this blog because I don't want my name associated with it in a Google search. Although I never write anything in a public forum like a blog that I'd be ashamed to have associated with my name (and you shouldn't either), it is illegal for me to use my position as a public employee to advance my religious or political views, and the pseudonym helps to preserve the distinction between my public and private identities. The pseudonym also helps to protect the people I may write about in describing public or semi-public events I've been involved with. You can read about my academic work on my academic blog --Pam Oliver

6 thoughts on “invasive species”

  1. My gardening experience has been enough to learn that I only have the time and patience for the most minimal amount of gardening. This year, I have hanging flower baskets, tomatoes and herbs planted. That may be too much for me to handle.

    I am thinking seriously about digging up my tiny lawn to plant some ground cover that looks good but is low-maintenance, like periwinkle. Any advice from real gardeners is appreciated. You may need to know in particular that whatever I choose has to hold up under trying conditions, as this patch is the only place we have for our 90-pound dog to pee.


  2. Regarding RoundUp: a couple of summers circa tenth grade I spent time “beanwalking,” where we would walk through this farmer’s field with spray bottles of RoundUp and spray weeds. We would also sometimes express irritation by spraying at each other. In retrospect I don’t think this was very wise. Also, there was a kid whose mother taught him to be terrified of the RoundUp and wore long-sleeve shirts and pants to prevent it from getting on his skin. We regarded this as the apex of prissy.

    (Apologies for the recent Iowa nostalgia kick.)


  3. I used to like ground cover, until I moved to a house where it runs rampant. Beware, Tina. Beware.

    Our yard is an invasive species haven, but it was only last weekend that we hired a guy to help with the yard who could tell me what should go and what should stay (although I’d love for it ALL to be gone). I filled my yard waste bucket up last week and will do it again this week. I think it will take me the summer to reclaim even a small portion of the yard.


  4. Jeremy,
    I always “walked the beans” with a machete. While that is still not a fair fight it is more fair than using a herbicide.


  5. Last year I shifted my strategy on fighting the invasive plants in one of our garden beds. I planted fast spreading native plants (to Wisconsin) which should, at least theoretically, have some natural advantage. The native and non-native plants are now battling it out back there and I’m taking a fairly hands-off approach – only pulling the thistles. At the moment it looks like the native stuff is winning!


  6. danielle: which plants are on each side of the battle? I don’t think violets can defeat garlic mustard, judging by my yard.


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