The discovery of a new plant at a Johnson County park was exciting, until conservationists learned more about it

Kirsten Morrow was taking inventory for Johnson County Conservation’s upcoming seed harvest events when she saw something unfamiliar at FW Kent Park.

It was the downy sunflower, or the helianthus mollis.

“I felt confident that it was new, and hadn't been there in previous years,” said Morrow, an education specialist with the county’s conservation department. “It was something that I hadn't seen before in the last nine years that I've been working here.”

Brad Freidhof, acting director for the department, said when conservation staff first discovered the downy sunflower at the park near Oxford, they were excited. They posted about the find on Facebook last week, telling followers that conservation staff were “excited and intrigued” by the plant, which is used by caterpillars and butterflies.

“We're kind of excited because it shows the complexity and diversity of the native planting restorations we do here at Kent Park and throughout Johnson County properties,” Freidhof said Wednesday. “But this is not a native sunflower to the state of Iowa.”

Freidhof said conservation staff did more research and learned the plant is “fairly aggressive, almost to the point of being invasive” in Iowa.

The downy sunflower is not aggressive or harmful to humans or animals, Freidhof said, but rather to other plants. It’s an allelopathic plant, which means it produces chemicals that can suppress or inhibit the growth of other plants.

Morrow said after learning more about the plant, the conservation team searched Johnson County and state records to find out whether the downy sunflower had been documented in recent years. They could find no records of the plant growing in Iowa in the last 20 years.

A volunteer botanist who works with the department found that historical records that identify the downy sunflower as native to Iowa may be inaccurate. Morrow said they are waiting on confirmation from botanists about the specifics of the misidentified records.

“We’re actually working with some botanists to dig in further to its historical range but don’t have answers from them yet,” she said.

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Freidhof said the plant is likely native to southern U.S. states.

“There were some accounts of possibly this plant being found in Scott and Muscatine counties,” Freidhof said. “But after further discussions with local botanists, they think those were misidentified, and they don't think it's ever been highly found in Iowa.”

Thomas Rosburg, a professor of ecology and botany at Drake University, confirmed that there has been debate about whether the downy sunflower is truly native to Iowa.

A guidebook of native Iowa plants called “The Vascular Plants of Iowa,” published in 1994, reported that the downy sunflower was not native to Iowa. But years later, Rosburg said a group of botanists reevaluated the plant and determined that the downy sunflower likely was native to southern parts of the state.

“That's the challenge,” Rosburg said, “the species that was found was just barely into Iowa.”

Rosburg explained that some plants can be native to one Iowa county, and non-native to another.

“It is critical to determine which plants are native to which county,” he said. “It can stop accidental planting from taking place.”

How will the plants be discarded?

Freidhof said eliminating the downy sunflower from conservation property will take time, possibly years.

“We suspect we have hundreds of plants [in FW Kent Park], so it's literally going to take staff, probably on hands and knees, crawling around in there, cutting seed heads off, putting them in a bag, and then chemically treating them with a little pen that kind of looks like a marker to try to destroy those individual plant communities,” Freidhof said.

This process has not started yet.

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Morrow said the Johnson County Conservation team has time to consult with experts to come to an agreement on a treatment plan, before the seeds of the downy sunflower can establish themselves.

Freidhof said when they do start disposing of the plant, they will be “very cautious” with the chemicals they use.

“When we do apply chemicals, we will put up some signage in the area, and most of those sites you'll see blue coloration. That's a dye that we add in with the chemical, so we know exactly where it was applied,” Freidhof said.

He added that the public is typically asked to stay away from the sites for 48 hours after the chemical has been applied.

Where did the plants come from?

Although the county still is determining the specifics of where the downy sunflower came from and when, Freidhof said he suspects the seeds found their way to the park from a bird feeder in the park or at a nearby home. They believe that birds may have picked up the seeds and deposited them in the park.

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“That's our best guess of how it could have got here. It also may have been somebody had the great intention of, ‘Hey, I've got some excess bird seed. I'm just going to go dump it out in on the ground,’” Freidhof said.

He added that one of the department’s concerns is residents depositing bird seed or plants in county parks.

“We try to not move plants around and encourage people to plant local plant communities so we don't end up with problems like this,” Freidhof said.

Rosburg said that Johnson County is likely doing “the right thing” by working to remove the downy sunflower, as some non-native plants in a new ecosystem can’t be regulated by other species.

“When you take a species from one place where it evolved and has these natural controls, and move it to another place ... you're basically making it into like a super plant, because now all of its natural controls were left behind,” Rosburg said.

While people may think of plant communities as static, Freidhof said that’s not the case.

“There's a lot of things that go into the complexity of finding a plant like that and then addressing how you're going to handle it right,” Freidhof said. “It’s a pendulum swing. It may not seem really exciting to the general public, but for botany people, for plant people, gardeners, it is. It's that emotional swing of finding a new plant, you're all excited, and then you find out it's not the right one.”

Olivia Cohen covers energy and environment for The Gazette and is a corps member with Report for America, a national service program that places journalists in local newsrooms to report on under-covered issues.

Comments: (319) 398-8370; olivia.cohen@thegazette.com