NEW YORK (CBSNewYork) — The weather is perfect for heading outside, but for some people a walk in the park is ending with a third-degree burn — and it’s not from the sun.

“It’s an evil plant,” said John Michael Rezes. “It’s an evil weed that needs to go away.”

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Take it from Rezes — you can look at the plant, but you definitely don’t want to touch it.

And Rezes is not the only one who feels this way.

“The plant, in addition to being an invasive plant, is a poisonous plant,” said Donna Ellis, with University of Connecticut’s Department of Plant Science.

It’s called giant hogweed, and experts say while it was first introduced to the United States from China as an ornamental garden plant, today it’s considered one of the most dangerous plants to take over New York and surrounding states.

Rezes said he simply brushed past some giant hogweed in May and to his complete shock, received a third-degree burn on his leg.

“I couldn’t really walk,” he said. “The scar is still there.”

And he’s not the plant’s only victim.

The New York State Department of Conservation wants people to be on the lookout for giant hogweed. The agency even issued a warning, calling it a “federally listed noxious weed” and employs eight field crews to track and kill the plant.

A map confirms the locations where they’ve already found it.

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“This is a young population of giant hogweed; seedlings that are probably just a year or two old,” said Ellis.

Ellis said the problem with the plant is its sap.

“That sap may get on your skin and the chemical reacts to sun,” she explained.

The reaction causes what’s known as photosensitivity.

“You can get what appears to be a mild sunburn at first and then within a couple of days, could lead to burns and blisters,” Ellis said.

“So if you get some on you, you should act quickly before you’re exposed to sunlight, because once the sunlight hits this stuff, it makes it toxic,” said Dr. Robert Korn.

Dr. Korn, Medical Director of GoHealth Urgent Care, said if it gets in your eye it can cause blindness.

And even when the skin burns go away, Dr. Korn said you may still see some scarring and discoloration for up to two years.

“If you’re exposed to it, you should immediately wash it off and stay out of the sun for at least 48 hours,” he said.

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If you find giant hogweed, never touch it without the proper protective clothing and goggles. Better yet, the state wants you to report it to them so they can send a team to remove it, free of cost.