Watch out for wild parsnip: Yellow-flowered plant’s sap can irritate skin; undisturbed, it’s harmless

Photos of a yellow-flowered plant that can cause severe burns have circulated social media this summer. The offending plant – the potentially invasive wild parsnip – can be found in every county in Illinois, including DeKalb County.

Richard Hentschel, the University of Illinois Extension Service horticulture educator for DuPage, Kane and Kendall counties, said that wild parsnip has been around a long time, and most likely was brought over by early settlers coming to North America as a food plant. The root of the wild parsnip plant is edible, just like the domestic variety.

“We seem to see a greater presence of wild parsnip than we have had in the past, and that can be attributed to our weather pattern – years where we have had hot and dry weather with excessive rains in the spring,” Hentschel said. “It has been able to flourish where other competitive weeds have not been, so it’s had a greater chance to establish itself.”

Hentschel said wild parsnip is most likely to be found in areas that are less maintained on a regular basis.

“It used to be in out-of-the-way, undisturbed areas away from mankind,” Hentschel said. “Now that I know what it looks like, I see it everywhere: roadsides, edges of woods – it’ll colonize an area of a field. So folks are going to likely run into it.”

Hentschel said the plant poses a risk at any stage of its development. Being able to identify wild parsnip as a young plant is as important as identifying an adult plant.

According to the Illinois Nature Preserves Commission, the young plant forms a basal rosette, and its leaves are alternate, pinnately compound – or arranged on either side of the stem – and branched with saw-toothed edges. The mature plant’s large yellow flowers make it more easily identifiable.

“If you’re mowing the ditch bank at the farm, or clearing an area in your back lot, you could easily get into it without knowing it if you didn’t recognize it as a younger plant. It’s very readily identifiable as a mature plant because it’s 4 to 5 feet tall,” Hentschel said.

Standing next to the plant will not give an individual burning blisters. But the combination of the sap on one’s skin combined with UV light exposure causes phytophotodermatitis, a condition with symptoms akin to a severe sunburn, according to an article by Christopher Enroth on the University of Illinois Extension website.

Wild parsnip plants do not seem any more prevalent along local roadways this year, said Nathan Schwartz, DeKalb County highway engineer.

“We see it every year,” Schwartz said. “We have not noticed that this year is particularly bad or any worse than any other year. Most of the roadsides have the nice white flowers, the Queen Anne’s lace, that’s noticeable.”

Schwartz said social media attention of late had made people more aware about the plant. He said the county highway department, which is responsible for mowing the right of way along county highways, does mow down wild parsnip and other weeds.

Those who mow are advised to wear long pants, Schwartz said.

Schwartz said the county also has a noxious-weed spraying program, where workers apply herbicide along guardrails and in other areas to keep down the population of thistles and other nuisance plants.

“We don’t see a lot of people walking around in the ditches anyway,” Schwartz said, “ but if you’re walking around in nature, you should know which weeds to avoid.”

In Kendall County, Northern Illinois University student Nick Gillette is working as an intern with the highway department, documenting locations of invasive species along county roadways.

Gillette said he’s run into a lot of wild parsnip patches.

“It is very prolific in the area – in Kendall County and other counties. It’s all over the place ...,” he said. “It’s [more prevalent] in areas it can get sunlight.”

Awareness, Hentschel said, is the key for those looking to avoid the plants’ burn.

“Over the years, a large percentage of the population can now recognize poison ivy, because we were taught [how to identify it], and exposed to it,” Hentschel said. “We have not been taught about wild parsnip yet, so we don’t recognize it as troublesome. There hasn’t been enough of it to cause a level of concern until now.”

Hentschel said that if someone has identified wild parsnip, they should take a shovel or long-handled pruners and push them in just beneath the soil at the base of the plant. Cut there, and let it lie and dry off naturally, and be sure to clean the tools carefully. Someone who knows they will be dealing with wild parsnip during the day should wear rubber gloves and a long-sleeve shirt. Because the reaction occurs in relation to sunlight, he also recommended working on the plant at dusk or dark.

“Don’t mow it; don’t weed-whack it,” he said. “Don’t break tissue [on the plant].”

• Daily Chronicle Editor Eric Olson contributed to this story.