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The City of Portland, Oregon

Environmental Services

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Phone: 503-823-7740

Fax: 503-823-6995

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Alien Plant Invader: Tree-of-heaven


It's been a while since we posted an invasive plant profile.  This one is about an invasive tree with some interesting characteristics.  We hope you'll help get it under control in Portland.

tree of heaven growing along curb

Sometimes referred to as ‘The Widowmaker’ and other more colorful language, tree-of-heaven (Ailanthus altissima) has made a good living filling in bad habitat like sidewalks and freeway sound walls, as well as yards, parks and other spots around the city. It’s well-known for using invasive roots and huge amounts of winged seed to clear a space for itself. 

In addition to these physical strategies, tree-of-heaven uses chemicals in its roots to kill off or limit the growth of neighboring plants. For all of these reasons, tree-of-heaven threatens a wide range of native plants and trees and reduces diversity in our urban forest. This rolls back the investment Portlanders have made in the healthy parks and natural areas that keep our water and air clean.

On top of its environmental impact, tree-of-heaven is hard on our homes and neighborhoods. The leaves of male trees smell terrible, like rancid peanuts or well-used gym socks. Because tree-of-heaven grows so fast, its wood is very brittle, leading to substantial branch drop. It doesn’t even take high winds for large limbs to fall on your car or roof (or head). Fast-growing trees can also become expensive to remove, so acting sooner, rather than later, is often the better choice. 

tree of heaven with fall colorsTree-of-heaven is a Class B invasive species in Portland (see the Portland Plant List). Fully-grown tree-of-heaven can be up to 60-70 feet tall. Trees flower in June or July, and form dense clusters of winged seeds by July or August. Leaves have 11 or more pointed leaflets, which are easily confused with those of black walnut leaves. Other tree-of-heaven look-alikes, such as ash and black locust, have rounded leaflets.

What can you do? Remove tree-of-heaven sprouts as soon as they emerge during the summer, though you may find that the “seedlings” are actually growing from the ends of the tree’s roots! This ability to sprout from roots makes tree-of-heaven hard to manage and difficult to remove, typically requiring an herbicide. But, if you keep at it, frequent repeated cuttings of sprouts and seedlings may exhaust the plant’s reserves and limit the re-growth. 

tree of heaven leavesIf the trunk is 12” or more across, or growing along the street, removal may require a permit. As a general rule, Portland Parks Urban Forestry regulates all street tree (as well as large tree) activities including permitting for planting, pruning, and removal. To obtain a permit, or for more information, please call 503-823-4489 or visit  

Property owners are welcome to contact Mitch Bixby at Environmental Services with non-permit questions.

The Plant Conservation Alliance also has an older, but helpful fact sheet at

Invasive species affect us all. They damage our forests, our streams and rivers, and our property. Nationwide, damages associated with invasive species are estimated to be $120 billion each year. In Oregon, the control of invasive weeds and the cost of the damages they create amounts to about $125 million each year. We know that it costs a lot less to control new invasive plants before they become infestations, but we need everyone’s help. Read more here about the problems caused by invasive species and why BES is particularly concerned about their impact on water quality.


Catch up on previous Alien Plant Invader posts:


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jeanine holly

August 16, 2020 at 12:08 PM

RE: Tree of Heaven

I live across the street from a giant, mother tree. The owners want to get rid of it (as do the rest of us), but can't afford the permit and removal fees. Does the city offer any financial help for invasive specie removal?

Also, I can't go anywhere in my neighborhood now without seeing infestations of Trees of Heaven. They are everywhere. I am willing to go door-to-door warning people to get rid of them while they can. Do you have info flyers I can hand out? (I have no printer, so a download isn't helpful.)

Is there a non-profit organization I can hook up with that might be of assistance?

Please advise.

-J. Holly


Peter Condra

October 2, 2020 at 8:54 AM

RE: Tree-Of-Heaven

Hello, I've been reading a lot about the spreading infestation of the spotted lanternfly which is causing massive agricultural devastation, and has no nearby solution in sight. Seeing as the tree-of-heaven is an important host plant for the spotted lanternfly, and is already a harmful nuisance in of itself, should this not be treated as more of an economic emergency?

I'd love to see a serious eradication program for the tree-of-heaven, in partnership with arborists and nonprofits like Friends of Trees that could offer to replace these trees on residential properties. For the ones growing along the side of the road, they should just be totally wiped out. Easier said than done, sure, but with the threat of of the lanternfly, we should be getting way ahead of this rather than waiting to have an out of control situation.


Glenn Day

October 23, 2020 at 6:12 PM

jeanine holly:

Did you find anyone that could help you folks out in your neighborhood? Looks like the same type situation near where I live.


jeanine holly

October 29, 2020 at 2:25 PM

Hi Glenn & Peter,

No help found, yet, for the removal of our Tree of Heaven. The city won't even waive the $100 permit fee and I've gotten bids to remove the tree for $900 to $3,500. Who can afford that?

I, too, wish there were some non-profit organization here in Portland that could help defray costs for removing such a noxious, invasive plant. I guess it takes someone willing to make it happen.

Now that my eyes have been opened, I see the rampant invasiveness of this thing everywhere. I've become obsessed. I am retired and can put in free labor, but it takes lots of money to take down large trees.

Anyone have any ideas? Anyone know how to do a GoFundMe?
Email me at Thanks, Jh


Glenn Day

March 6, 2021 at 7:04 PM

About the same story here. I do not understand why the city will not help. Have tried everything I can think of. We do pay their wages. I guess that does not count.

There are only four. Over here, but many more will be growing if nothing is done to the four. I am tired of trying to remove the 'sprouts'. And tired of all the branches falling down..but my thoughts as a tax payer obviously do not count.

Think it best I say no more.


kevin Woodruff

June 20, 2021 at 11:55 AM

Same problem in my neighborhood. We actually paid to have a neighbors tree of heaven removed (renters) a few years back. We used fair weather tree experts. which if I remember correctly, was pretty reasonable. Maybe $4-500?

Still, we’re stuck with so many up-shoots surrounding our property. Feels hopeless to conquer, especially without support from the city.


Glenn Day

June 29, 2021 at 12:14 PM

Almost July now. People are letting them grow. I have talked to a couple, but they refuse to do anything. Have even given them sites like this to learn information. Winds blew the seeds quite a distance from the four trees; even during winter months. They are sprouting up all over the area now. They grow faster than lightening it seems. Guess people want to have shade, and suffer consequences. I hate the things. Only one neighbor has tried to get rid of them on her property. But now, there are many that are growing that people will not do anything about. Try to tell them, and just get ignored. In essence; we all will suffer more and more over time. Have some that I consider hazardous and dropped a big branch into the alley. But the city will do nothing. Nor the owner of the property. And there are four full grown over there that have been causing bad things for people. But they are 'shade trees'. And a lot more are now growing in the whole area now. Am sure it will increase the value of houses when word gets out about the trees. (Being sarcastic). I do not understand some things. And the city of Portland will do nothing. Even though they say they are nuisance and and invasive species. If another big branch falls and hits a car or a person, maybe someone will do something. Small branches fall all the time. But that one big one could have killed a person. Look to me that they are out of balance and two of them are going to fall down some day anyway. Already talked to my insurance company. The guy across from me told me I was full of xxit. The city would do nothing. I give up. Anyone want to buy a house with all those trees within a few feet of them? And even on the property the house is on? One couple bought a house that is next to two of the original four. The realtor told them the name of the trees, but nothing else. The prior owner left because of the trees!! (Next door to her). Was constantly picking up sprouts and having to deal with all the crap. And 'billions' of leaves.
Too late for me to move. I am on a fixed income and this place is paid for. Difficult for us to even enjoy our backyard that we paid for. Never dreampt this would have happened. But it has.


Glenn Day

June 29, 2021 at 1:34 PM

My own experience the past five years or so has been that even using a herbicide, it is difficult get rid of them on this property. And I found out that many people refuse to use a herbicide. Takes me a number of times if I let them grow a couple feet. They just keep coming back up every year. But the original four trees are higher and have many more 'flowers and seedlings and branches. The owner of that one property where the trees are at kept mowing the grass over there a lot. Guess that is one way of keeping them down. The new owner does not do that. One new couple lost a garden at their place. Said a 'shooter' hit it. I guess that is the main root that is difficult to get killed. But they have some growing over there now that are good size. Seems people refuse to do anything even when shown how to remove them. Might be kind of nice if the city would do a little publicity about them. Maybe people would then listen and learn. Even if the city will not help, they could give some more publicity about the things. My opinion. I don't think people believe me when I tell them about the things. With the exception of a neighbor next to me. She actually came to this site and read what I had told her. I did not even know all the danger of them until I found out the name of them. I was originally told they were some other kind of tree. But last year a neighbor that moved, had some on their new property and discovered the name and reputation of them, and told me and others around here. I found this site, plus many other sites that say nothing but negative things about them. If people do not remove them we will have a 'forest' over here. They grow fast!

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