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The City of Portland, Oregon

Environmental Services

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Phone: 503-823-7740

Fax: 503-823-6995

1120 SW 5th Ave, Suite 613, Portland, OR 97204

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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.

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