split image of the tallest poison ivy plant

A Canadian man had a rash of good luck when he discovered the tallest poison ivy plant on 12 March 2023. 

The plant, which usually grows between 1 to 4 feet (30 to 120 cm) tall, measured 20.75 metres (68 feet).

That’s about the same length as two school buses!


And it’s fair to say Robert Fedrock of Paris, Ontario, was shocked to discover it.

“I have a wooded area on my farm, and I spend considerable time out there,” said Robert. 

“Several years ago, I was making a new walking and biking trail through a low-lying area just on the edge of a swamp.  I happened to notice a very large vine growing up a tree near the trail about 2 metres (6.56 feet) away.” 

Although there are many vines in the area, which is located near the Grand River, this particular one caught Robert’s attention because it was very large (about 15 centimetres (5.9 inches) in diameter) and completely covered with aerial roots.

In fact, the entire vine was covered with a mass of aerial roots from the ground to well above eye level. 

“It took me a while to figure out what kind of vine it was because the leaves only started about 3 metres (9.84 feet) off the ground, and the aerial roots were such a tangled mass that I didn’t recognize it as poison ivy right away,” said Robert. 

“At the time I found it very interesting and decided to identify the vine. Usually, large poison ivy vines have a bark that is smoother and lighter brown than common grape vines, with patches of smaller aerial roots.” 


The vine did seem to have that appearance much higher up, but a particularly dense patch of common buckthorn blocked much of the view. 

“Had I not been building the trail so close to this plant, I may not have found it because of how dense the woods are in this area,” said Robert.

The day after its discovery, he went out to see if he could get to the leaves and sure enough, he did manage to see the leaves a couple metres above his head when he pushed the buckthorn away. 

He could also see high enough up the vine to where the aerial roots thinned out a bit, and realized it looked much more like a poison ivy vine.

Since the plant was located near his trail, Robert decided to dig out the common buckthorn around it for an unobstructed view of the whole vine. 

During the process, which involved quite a bit of digging with dirt and leaves flying everywhere, he wound up getting poison ivy rashes on his hands, arms, face, and stomach, which he says was not entirely unexpected. 

“I was hoping to avoid it, but some hazards are inescapable, and the cause was worthy,” said Robert. 

“The oil that causes the rash is also in the dead leaves which litter the area.  It seeps into the dirt, and the underground roots also contain it and were likely intermingled with the common buckthorn roots I was digging out.” 


At this point, he knew he had accurately identified the plant as poison ivy.

Robert says when he first came across the plant, he could only guess its height.

“I discovered it in the summer, and I knew the tree it was growing on to be dead, so I could see the vine went nearly to the top if I got far enough away to see it, but the woods are dense, so I only knew that it was ‘pretty tall’ at the time,” he said. 

“The tree it is growing on is a white ash tree.  Pretty much all the white ash in this area have been dead for 5-10 years, as there has been an infestation of the emerald ash borer that unfortunately has killed most mature white ash trees.”

At the time, Robert had no idea it was the tallest poison ivy plant but given that the plant was far thicker and had more roots than any of the pictures he found on Google, he suspected that it might rank quite high. 

He began jokingly telling his friends that he had the world’s tallest poison ivy plant, and a friend suggested that he actually submit it to Guinness World Records. 

After looking at the Guinness World Records website, he figured it may not be a bad idea.

“I thought it was the coolest thing in the world. I am fascinated by the natural world and I’m always looking for the most interesting things in the woods; they make good destinations for my trails, but in this case the trail found the interesting thing,” said Robert. 

“I also enjoy the reaction when I point out to people that this great big hairy vine is poison ivy. No one has THAT in mind when they think of poison ivy, and most people are scared to death of a tiny plant with just a few leaves they see on the forest floor.”


Robert is thrilled to have a Guinness World Records title and thinks it’s an interesting little fact of history to have a part of.

He says other than clearing away the common buckthorn trees, which are an invasive species, he left the poison ivy plant untouched. 

“The rash spreads if the oil is spread, so if it gets on your hands it will end up everywhere you touch,” said Robert. 

“You can’t build up a tolerance for contact with the oil, and it’s possible that repeated exposure can make each subsequent exposure worse, which if true would be unfortunate.”

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