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A Small Exercise in Hope for Greater Yellowstone

In trying to rid an area of invasive plants, MoJo columnist Susan Marsh explains how even small acts of conservation count

Musk thistle is an invasive species, hardy and adaptable with prolific seed production. Volunteers attend "Thistle Thursdays" in Jackson, Wyoming, to help clear away this nonnative plant and do their small part to protect Greater Yellowstone. Photo by Susan Marsh
Musk thistle is an invasive species, hardy and adaptable with prolific seed production. Volunteers attend "Thistle Thursdays" in Jackson, Wyoming, to help clear away this nonnative plant and do their small part to protect Greater Yellowstone. Photo by Susan Marsh
by Susan Marsh

For the past couple of years, I’ve participated in “Thistle Thursdays” during which a group of volunteers spends the morning attempting to tamp down the steady march of musk thistle along a popular trail near Jackson, Wyoming.

Musk thistle is native to Eurasia, most likely introduced by accident since its seeds have large dandelion-like parachutes allowing them to drift on the wind and land just about anywhere, including on cargo ships. The first recorded observation of this plant in America was in 1953. Since then, it has thrived in nearly all of the continental U.S. and seems particularly satisfied with conditions in Teton County.

For as long as there have been land-based plants, they have made their way around the world in all kinds of ways—by windblown or waterborne seed, on floating objects, and by hitching rides on migratory birds and other creatures. So what makes musk thistle of particular concern?

Like many invasive plants, it’s a vigorous and adaptable species and its seed production is prolific. A few plants can soon become a large population as they
successfully compete for light and nutrients with native plants, eventually replacing them entirely. Herbicides used for weed control further damage the few broad-leafed natives that may coexist with the musk thistle, and treated areas often end up dominated by nonnative grasses. In short, an invasive weed like musk thistle can have a negative impact on the biological diversity of the places where it grows.

Unlike native thistles, whose flowers are a delicacy to elk and horses, musk thistle is not eaten by wildlife or livestock due to its spiny leaves and flower bracts. Because it is unpalatable, nearby meadows and grasslands can become degraded as grazing animals avoid the thistle and forage on other plants. This reduces their vigor and allows the musk thistle to invade even more space.

Tackling a stand of mature, blooming musk thistle requires care and determination. All flowers and buds are removed and placed in bags or bins. The plant, a long-lived biennial that dies after bloom, must still be cut below well the base or pulled if the ground is wet enough, otherwise it will put up more flowering stems. The pulled stalk can be six feet tall and contain enough residual energy to create more flowers, so we use clippers to cut them into smaller pieces if necessary. Protective gear includes heavy gloves, long sleeves and sturdy boots.

Thistle Thursdays help me feel like I’m making a tiny contribution to the health of the environment. But that doesn’t stop me from asking myself a more basic question: what do we mean by “weeds?”

I suspect most of us would say that a weed is a plant that doesn’t belong where it is growing, and is not native to that place. But what we call weeds largely depends on who we are and how we use the land. Maybe a more accurate definition of a weed is any plant that we judge to be at odds with our particular desires and needs.
The work is daunting, and perhaps fruitless in the long run. But isn’t all the work we do to build a better world subject to potential failure? Yet, we keep doing it ... Thistle Thursdays help me feel like I’m making a tiny contribution to the health of the environment.
If I were a more persnickety gardener, or a farmer who depended on my crop for a living, a weed would likely be any plant, native or otherwise, competing with my beans or wheat or spuds. Hand spinners of wool may delight in finding a stand of nonnative and toxic-to-horses tansy, whose mustard-yellow blooms yield a rich dye. Ranchers whose cattle graze the national forest would prefer to see a minimum of tall larkspur, which is toxic to cattle. But it's a native plant, and belongs here. A noxious weed to some; a component of the beautiful, tall forb cover type to others.

Musk thistle, like most nonnative plants, isn’t 100 percent evil. Bees, butterflies and other pollinators are attracted to its wide table of magenta disk flowers. It blooms in mid to late summer when many of the native wildflowers are on the wane, offering an alternative to insects. Its seeds are eaten by songbirds, and they contain a compound believed to help with liver function. In places where it’s native, the pith of the stalk is cooked and eaten by people.

While musk thistle is the focus of attention during Thistle Thursdays, it’s joined by hound’s tongue, salsify, toadflax and other nonnative plants, which we also try to remove before they go to seed. Success, however, is a far reach: Jackson Hole has witnessed a startling and steady increase in a number of invasive weeds that were rare or absent 30 years ago. In August, hillsides and river bottoms carry a pinkish blush from large swaths of knapweed. The spread of cheatgrass is easy to spot by its straw-colored patches on the hills around the valley.

Musk thistle stand before treatment. Photo by Susan Marsh
Musk thistle stand before treatment. Photo by Susan Marsh
I suspect that despite our best efforts, these nonnative plants will work themselves into the ecosystem and become part of it, perhaps to the detriment of native plants, wildlife and the fire-resiliency of our community, since some of these plants mature and dry quickly or contain flammable compounds. Given enough time, natural processes will sort them out, but that sorting won't necessarily reflect our preferences. Rather, those species best suited to a rapidly changing climate will likely win out over the beloved native wildflowers that are less adaptable.

On Thistle Thursdays, people whizzing past on bikes yell thank-you’s while some friends shake their heads sardonically. “You’re pissing in the wind,” one tells us. But before-and-after photographs show that our three hours of work made a difference, at least for this year and in this small place. Perhaps our efforts will give native plants a head start next season. And there is some satisfaction involved: at the end of a morning weed pull, the beds of two pickup trucks are filled with bags of musk thistle blossoms and I can almost feel the remaining native plants stretching out and breathing a sigh of relief.

We know that we’ll be back next year in the same place. We will have missed some rosettes that were waiting to mature and bloom, and there is a constant seed source from upwind where thistle patches aren’t being treated. There is no doubt that this can be discouraging work, and I ask myself whether the time spent is worth it. We think we’re doing a good thing, using our hands instead of poisons, allowing native plants to come in behind the thistles instead of the nonnative grasses that dominate after musk thistle has been sprayed.

In places where some of us have been working every week (or day) for several years, the land looks notably weed free. Yet we never indulge in self-congratulation.
Musk thistle stand after treatment on a Thistle Thursday. Photo by Susan Marsh
Musk thistle stand after treatment on a Thistle Thursday. Photo by Susan Marsh
What will happen when we die off and the next generation doesn't want to spend half a day each week cutting down musk thistle as thick at the base as my wrist and whose leaves and flower bracts have spines that penetrate thick gloves? Part of me admits that I am likely just pissing in the wind, and part of me is glad I did my little bit, for however long its effects may last.

The work is daunting, and perhaps fruitless in the long run. But isn’t all the work we do to build a better world subject to potential failure? Yet, we keep doing it. We want to help, if only a small amount, and if only temporarily. The work feels like service, like the opposite of cynically saying, “The hell with it. I’m just going to enjoy my life for as long as it lasts.”

Pulling weeds and filling buckets with their flowers is not so different from tending a garden at home. We’re tending a larger garden, of course, the Eden that we inherited. Most of all, we’re expressing what is perhaps the most fleeting and precarious of human sentiments these days: hope.

Susan Marsh
About Susan Marsh

Susan Marsh spent three decades with the U.S. Forest Service and is today an award-winning writer living in Jackson Hole.
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