Heaven sent or hell bent?

There’s a tree that’s widespread in my NE Portland neighborhood.


No one plants them.  Because of high rates of seed production and germination, they grow as volunteers.  You might not notice the young tree hiding at the base of a fence post.


It might show up as a welcome bit of green in a neglected spot. It’s not bothering anyone in a weedy curbside strip.


Or distracted by garden flowers, you might not notice it’s there.


Tree of heaven, Ailanthus altissima, is not a tree most people want to host on their property. It’s considered highly invasive.  It’s quick to establish on disturbed sites and is thicket forming. Left alone, before long a yard might host 80-foot specimens to the exclusion of any other tree.


Once it gets too big to pull out completely by hand digging, it’s very challenging to remove this tree.  Cutting stimulates more vigorous growth, it resprouts from stump and roots tenfold, and in most cases it can’t be killed without chemicals.  Here’s a tree around the corner on my block someone has attempted to thwart by girdling.


How much is this tree suffering?  Not very much.


It doesn’t happen overnight, but let go for too long and eventually you’ll see a rearrangement of any concrete structures in the rootzone of this tree.


Not to turn this into a horror show, but I couldn’t resist showing a healthy little sprout from a mass of stumps that otherwise gives the appearance of having been put to rest long ago.  The base is over 5 feet long.


The time to get rid of this is now, when it looks like this:


Ailanthus altissima can be mistaken for other trees with pinnately compound leaves. Distinguishing features include leaf arrangement, number and shape of leaflets, flowers and seeds.  OSU Department of Horticulture lists some useful facts here.

Other resources can show and inform better than I can.  Incomplete at best, here’s just a few tips. Walnut leaves are similar, but English walnut leaflets are larger, rounder, and black walnut leaves are toothed on the margins.  For walnut, look for the large green fruits, or furrowed bark pictured below.  Tree of heaven bears seeds in a samara like maples, and has smooth bark.  Walnut can appear similar as a young tree and like ailanthus they also get tall, shading out other plants, and produce toxins to inhibit growth of other near by plants. (Yes, you might want to yank those seedlings too.)

IMG_4456      IMG_4490

Finely toothed margins on sumac leaflets, below, distinguish it from the tree of heaven.


On the reverse side of the leaflets, look for a small circular gland at the tip of the lower lobes for positive identification of Ailanthus altissima.


Here is tree of heaven in flower:


As humans, it’s inevitable at times that we assign  judgement to plants based on their aesthetic value for garden use or ecological function in natural areas.  Even though images like the one below keep me awake at night, I have a little trouble with this because of course trees themselves are without intent, positive or negative.


I look over my back fence at a quickly maturing specimen and wonder how large it will get.  My hope is that it will be removed some day soon, halting damage to the home’s foundation and preventing seed dispersal to my yard and many others.  But I’m skeptical — each tree of heaven in my neighborhood is a short stone’s throw from the next.

For further reading, here’s a perspective and lots more information I encountered on a blog called Necessary Forests.  The City of Portland Bureau of Environmental Services also has this bulletin on Ailanthus altissima.

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14 Responses to Heaven sent or hell bent?

  1. Ricki Grady says:

    Close as we might come to “Triffids”? I think you should make sure the neighbor with the tree reads this.

    • Ricki, I have never seen anyone coming or going from the house behind me and no one ever in the yard, although I see the lawn is mowed regularly. I feel shy about knocking on the door to talk to them about the trees, but maybe it’s time to find some courage for a friendly chat.

  2. Julie Fukuda says:

    This is an excellent post. I wish you could send it to a local paper, I have seen these growing at one of the military bases here in Japan and yes, there is never just one! We have invasive plants here too and on a walk with the dog, I can’t resist bending over to pluck out those little sprouts before it gets too late. I noticed last week, someone had cut off a single tree leaving a stump from which were sprouting about six new ones.

  3. Miss Dove says:

    you’ve got to admire a survivor! it is humans that have created the environment for ailanthus to thrive, by disrupting the ecological balance. true of crows also. excellent post! i am inspired to do some guerrilla ailanthus removal …

  4. My friend and neighbor Bridget removed 3 (or more?) of these from her back garden a couple of years ago. There are still sprouts popping up a good 20 ft from where the trees were. It’s a scary thug indeed, thanks for writing about it!

  5. Heather says:

    Ugh, this one is the worst. Thank you for posting this!

  6. It’s s shame these trees are so invasive, because they are really quite attractive. But a menace is a menace. Thanks for being a voice of reason!

  7. seaneugene says:

    Thanks for the great article. I think we have some of these saplings in my backyard in SW Portland. Time to exterminate.

    • This time of year, look for the heart shaped leaf scars on the trunk for positive identification. Based on what I’ve read, the best time of year to remove (if they are not mature trees) might be end of summer/early fall when energy storage is depleted. Study up, and good luck!

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