By MAUREEN PICHÉ

Most St. Lawrence County residents can spot a poison ivy or sumac plant with no problem, but there's a little-known pretty looking weed growing along roadways, in open fields and backyards that is just as toxic.

Wild parsnip, a deceptively benign looking invasive species related to Queen Anne's lace and carrots, can be found just about anywhere you look in the county this time of year, according to Paul Hetzler, Canton-based horticulture and natural resources educator for Cornell Cooperative Extension.

But before you go to pick this plant, be warned: its sap contains chemicals that cause a toxic skin reaction that results in burns, pain and blistering.

Similar to Queen Anne's lace in appearance, it can reach up to 5 feet tall and has flat-topped clusters of yellowish-green flowers, according to the New York State Department of Environmental Conservation website. In addition, it has a hairless green stem with vertical grooves, and compound leaves that resemble large celery leaves.

And there seems to be no effective way to slow down the spread, Hetzler said.

“Nothing seems to be a good biological control,” he said. “It would appear mowing activity along highways scatters the seeds.”

Hetzler had his own personal encounter with the toxic plant while whacking weeds in his backyard. He was unaware that wild parsnip sap had come into contact with his skin.

“It requires activation by sunlight,” he said. But even on a cloudy day, ultraviolet light will still activate it.

Hetzler said he didn’t immediately notice a toxic reaction; in fact it can take a couple days. Eventually, his skin turned purple and blisters broke out, very similar to a poison ivy reaction. But instead of intense itching, there was pain.

The pain only lasted a few days, Hetzler said, but it took weeks before his skin looked normal again.

Another difference between the two plants: To get a poison ivy reaction, a person usually needs to be sensitized by a prior exposure, according to the DEC. Poison ivy causes an allergic response and people's individual sensitivity varies. Wild parsnip will cause burns in anyone and can cause more serious injuries with longer-lasting effects, the DEC reports.

Hetzler said the burns can sometimes be severe enough to require medical attention.

If accidental exposure to the plant sap occurs, wash the skin with soap and cold water as soon as possible. And protect the skin from sunlight for at least 48 hours, the DEC recommends.

Emily Hutchison points out most people aren’t even aware of the dangerous plant.

“My 9-year-old son was helping weed around our house (along the edge of the woods),” she said. “He had what I initially thought was poison ivy, but with none of the itching or pain. Once the severe blisters began, I did some more checking, and he apparently had a wild parsnip burn.

“None of my North Country friends and family had ever heard of this before - including me!” the Massena resident added.

Hetzler said getting rid of the plant is no easy feat. It grows a fleshy tap root that is very difficult to completely remove from the ground by simply pulling.

He recommends wearing long sleeves and pants and rubber gloves when dealing with the weed. Constant mowing will eventually kill it, but that takes a lot of time, he said.

“The best thing to do would be to cut the root with a garden spade,” he said. “If you can get 80 to 90 percent of it, that should destroy it.”

Another option is applying an herbicide such as Roundup while the plant is still young.

If you’re cutting a flowering plant, be sure to either burn the seed heads or throw them in the trash—not in the compost pile, he stresses. Many seeds will survive the composting process.