Wild parsnip, a dangerous invasive plant, is thriving in Michigan’s Upper Peninsula


A dangerous invasive plant has spread across Michigan’s Upper Peninsula, posing a hazard to anyone who encounters it unknowingly on roadsides, trails, public parks and other areas where mowing and other activities have provided the prodigious plant an opening.

Wild parsnip, known by the scientific name Pastinaca sativa, contains toxic compounds in its juices that, when exposed to ultraviolet light, cause nasty and painful burns and blisters called phytophotodermatitis that can be long-lasting. Here are some photos to horrify you.

The perennial is a member of the carrot family and is a prolific self-seeder. During a recent trip to the U.P., I saw it all over the roadsides and encountered it on an overgrown trailhead in the Hiawatha National Forest, where it was thick enough to turn me back, since I was in shirtsleeves and shorts.

“Five years ago it was not like this at all,” said Nick Cassel, coordinator for the Three Shores Cooperative Invasive Species Management Area, a division of the Michigan Conservation Districts that covers the eastern U.P. counties of Chippewa, Luce and Mackinac.

Officials say wild parsnip is now widespread across the U.P. It’s believed to have been introduced in Wisconsin, where it’s now ubiquitous. In fact, that’s the only reason I was able to identify it: A friend of mine who lives in Wisconsin has pointed it out to me and told me about his wife’s experience being burned by it.

imageI did not find any information about wild parsnip among the publications published by the state Department of Natural Resources or the U.S. Forest Service highlighting problem invasive species.

The plant looks a lot like Queen Anne’s lace, only with yellow flowers. Here’s how the Forest Service describes it:

While it looks similar to several other carrot family plants, the flowers of Wild Parsnip are yellow and the stem is smooth and green with very few hairs. Its leaves are long, saw toothed, pinnately compound and form a basal rosette during the first year. The leaves are further divided into leaflets that grow across from each other along the stem, with 2 to 5 pairs of opposite leaflets. In its second year from June until mid-July, and sometimes even through late summer, the plant flowers. Its flowers are small and yellow with five petals and there are hundreds per plant. The flowers are arranged in 2-6 inch wide umbels at the tops of stems and branches, and there are usually no bracts, and very small or non-existent sepals at the base of the flowers.

The Forest Service says it’s aware of the problem but has limited ability to combat it. The agency typically focuses on cases where wild parsnip is threatening rare plant or other species but hopes for a boost in federal funding to help fight the noxious weed.

So much of the task of tracking wild parsnip and trying to eradicate it falls to the so-called CISMAs like the one Cassel oversees. These organizations are grant-funded and partner with state and federal agencies, tribal governments and other groups to identify problem areas on public and private lands.

Cassel said his group has enlisted county road commissions as his frontline warriors in trying to manage the weed. Three Shores staff have been helping to train mowing crews, including subcontractors, to adjust their mowing schedules to avoid spreading wild parsnip seeds and worsening the problem.

A typical U.P. roadside.
A typical U.P. roadside.

That means mowing roadsides first in early to mid-June, when the plants are nearing 2 feet in height, and then again in August, to ensure the plants don’t have enough energy left to produce seeds. And then repeating the process over several years, since wild parsnip seeds can survive in soil for years.

“They already realize it’s an issue,” Cassel said of the local road commissions.

While wild parsnip was all over highway roadsides, I also saw lots of it lining the roadsides in the northernmost lower peninsula. The plant has also been identified growing near Kalamazoo. That suggests it’s only a matter of time before wild parsnip becomes established all over Michigan.

Cassel said his group has seen success in eradicating the plant in certain areas, citing a public playground in St. Ignace where the plant was encroaching and posing a menace to children. But as is the case with many invasive species, it may be more a matter of managing the plant, and learning to live with another unwelcome invader.

Creative Commons photos by John W, Ellen Macdonald and notman05

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