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Landmarks: That spiky plant you see everywhere along area roadsides? It’s teasel, and it’s just one of many invaders
Sunday, February 28, 2021 Daily Southtown by Paul Eisenberg
The days are getting longer, the weather will be getting warmer and the warriors are preparing once again to do battle to repel and remove the invaders that have staked a claim to our land.
The fight is essential, because once established, the invaders can make it so nothing else will thrive.
For Jeff Maharry, a teacher at the University of Chicago Laboratory Schools, that means heading out in early spring to his assigned territory in the Izaak Walton Nature Preserve near his home in Homewood when he gets the call to arms.
His enemy is a plant species, but it’s “a real monster,” he said. Teasel plants, which in their second year “send up a 6-7 foot stalk of spiky, thorny nastiness,” have taken over small sections of the preserve, allowing nothing else to grow.
Wielding more than just skin-penetrating physical defenses, it also fights back through reproductive prowess.
“One of its weapons is it’s prolific,” Maharry said. “It makes so many seeds.”
Once it flowers, those seeds number in the thousands for each plant, said Becky Collings, senior resource ecologist for the Forest Preserves of Cook County, who counts teasel as just one of the enemies of the preserves.
But it’s one that’s gaining more and more notice, mostly because it’s most often found in areas that have been heavily impacted by people, such as highly visible roadsides. It could be the poster child for National Invasive Species Awareness Week, which just passed.
I’ve been aware of teasel for years — it’s a remarkable looking plant that has been in North America since the 1700s and may have been brought intentionally from its native Europe and Asia and used in textiles, according to a U.S. Department of Agriculture plant database. It was reportedly being cultivated in New York in the 1860s, and gradually spread across the country.
Over the last few decades, its movement has been much faster. I’ve noticed it pop up in more and more places. It nearly lines 183rd Street between Tinley Park and Homewood.
And it’s using our roadways to travel. Ironically, our tendency to cut plants down is helping teasel to thrive.
“This plant does really well in disturbed areas that humans have messed with a little bit, so mowing is the worst thing you can do,” Maharry said. “It gets caught in the blades, and then they go down a mile and they drop the seeds there. Mowing just makes it worse.”
Even cutting the plants by hand can be counterproductive.
“If you cut it in July with a machete, hack it off at ground level, it doesn’t kill the plant because it has energy stored up in its tap root,” Maharry said. “So it will regrow and make new seed heads. One cut won’t do it. You come back next week and now there are three or four new shoots coming out. It’s a real monster.”
But if it’s a plant that’s growing in an already disturbed area such as along roadways, that can’t be so bad, can it?
Yes, said Collings, the Cook County ecologist, noting that in its first year it hugs the ground before shooting up its distinctive, seedy spike in its second year.
“It can really cover a lot of the ground with its lower leaves and form a carpet and prevent other, more desirable vegetation from growing,” she said.
“Roadsides can provide very important habitat and corridors, a ribbon of green space that connects different preserves and parks. Anything we can do to improve the habitat that’s available, even on the side of the road, can be important for birds and pollinators.”
Teasel isn’t the worst invader in the forest preserve system. Collings said officials are more concerned about shrubby plants such as buckthorn and nonnative honeysuckles, which can create a dense layer in wooded areas that prevents any ground plants from growing.
“That can have cascading effects on the health of the whole site,” she said. “There’s not as many plants to hold soils in place, and they’re not providing the nectar and pollen for insects. There’s more bare ground and less biodiversity.”
Forest Preserve workers just wrapped up a wintertime effort to eradicate the shrubby invaders, and this spring they’ll resume a prescribed burning program that helps control invasive plants from more open areas.
That includes Orland Grasslands, where one of the latest threats to the natural ecosystem has made an offensive: the callery pear tree.
A fast-growing ornamental that produces lots of white flowers that have a “pungent smell” in the spring, it also is an aggressive reproducer and it’s “used a lot in new developments,” Collings said.
“Callery pear has found its way from ornamental plantings into the (Orland Grasslands) site and it’s moving across the prairie fairly quickly,” she said. “We’re trying to control it because we don’t want to lose prairie habitat to trees and shrubs. It’s a bit worrisome for me because it’s still being planted a lot in ornamental settings.”
Because it’s a plant that’s profitable in the nursery trade, there’s a strong effort to keep the callery pears in production, though there’s an increasing call for it to be placed on official lists of invasive species.
Collings knows the effort in Orland Park is just another step in the ongoing program, and the war against invasive species in Cook County will never be over.
“Our goal is to get to the point where maybe we haven’t eliminated every invasive species, but with regular fire and some maintenance we’re at a point where invasive or nonnative species are kept in check and not taking over and displacing native plants,” she said. “The goal is not to get to zero, but to get to a manageable level where we still have thriving native vegetation.”
It’s a fight she’s happy to make, because natural areas are so valuable. They clean the air and water and provide habitat for an array of plants and animals, and they offer respite for humans living in an urban and suburban environment.
“Even if you never visit, knowing it’s there provides a benefit to you, knowing that you could go there and escape your day to day world,” she said. “Just having that in your mind just helps dealing with urban stresses we all face.”
Likewise, Maharry will head to Izaak Walton to do battle against teasel once again this spring.