Angelenos take on the (seemingly) impossible task of controlling Tree of Heaven

It's The Terminator of timber, and eradicating the invasive and stubborn Tree of Heaven can feel impossible.

After our recent story on this almost indestructible tree, we got connected to a couple of Angelenos who told us about their own dealings with the infamous plant.

The high school assignment

Ryan Long is a science teacher at South Pasadena High School who's been inspired to turn his lifelong tussle with the rowdy tree into an extracurricular class assignment.

Long grew up in the San Gabriel Valley, and one of his chores as a kid was to pull out Tree of Heaven in the backyard of his childhood home.

"The goal was not to let it get overrun, so it never quite did, but they were a constant problem," Long said.

Long's father is a biologist and worked for Parks & Recreation to oversee the conservation and maintenance of natural areas in L.A. County. Because of that line of work, his father dealt constantly with invasive plants like Tree of Heaven. So the young Long already heard about the species' awesome drive to survive.

"If you're getting them when they're young, those plants are a little easier than when they're older," Long said. "If you leave roots underground, they're going to grow right back."

Fast-forward to 2024. Long is teaching a class in biomedical sciences. To satisfy state requirements, ecology must be part of that course, Long said.

He said the Tree of Heaven came to mind immediately.

"I thought this would be a good side project for them to get to know this plant, and it's pretty pervasive around most communities around here," he said. "My main goal was to get them out there looking for them."

So Long told his students to go find the plant in the city, using photos and research they find on the internet to help them make a match.

"Their job was to go out there and get a photograph and document where they found it. It was pretty much as simple as that," he said.

Long said he was surprised at how many students were able to correctly identify the tree. Some brought back not just photos — but seeds and the plant itself.

"A few days ago, my room started filling up with these plants and the smell of a Tree of Heaven," he said. "Once you get to know it, especially if you've had to deal with them for a while, it's a terrible smell."

But it's all for a good cause. "I think they learned a lot about plants in general... so they're getting a bit of botany there too, which thrills me a lot," Long said.

The Terminator exterminator

What makes the Tree of Heaven so difficult to eradicate is its root system, which spreads horizontally and produces shoots and new growth when the tree is cut or damaged.

To get rid of it once and for all is to get rid of its roots.

Business owner Bill Neill's former day job was in the petroleum industry, but all the while, he was nursing a side love in ecology, with a particular niche.

"Invasive plant control became an avocation," Neill said.

Back then, Neill and his volunteer group worked on controlling tamarisk, or salt cedar — an invasive tree from Eurasia that had taken over certain desert areas under the management of entities including government land agencies.

After retirement in 1999, Neill turned his hobby into a business, Riparian Repairs, partnering with a botanist friend to eradicate invasive plants in the Southland.

He remembered visiting Malibu Creek State Park, and was introduced to a scraggly-looking plant called Tree of Heaven. Much of his work now focuses on the removal of that tree , including for many homeowners.

His methods vary, depending on the size of the grove and the size of the trees. In natural areas, he might inject herbicides into cuts he makes on the trees. In most backyards, bottle-spraying the lower trunks of saplings with an herbicide should do the job, Neill said.

But there are outliers. He remembered a Tree of Heaven he took down at a house near Palmdale. The tree was causing damage to the driveway and sewage system.

"It's not necessarily in all cases that it's a problem," Neill said. But "usually people don't become aware of it until there is a problem."