Here is a link to an article that I came across that might help: http://www.themondaygarden.com/archives/2005/01/ailanthus_and_s.html
You can also try pulling off a leaf and smelling it. Ailanthus smells horrible.

Ailanthus smells bad. break a leaf or twig from a large Ailanthus, learn the smell, then do the same to small ones until you figure out how to tell the difference. i am sure there is a way to tell visually, but it probably has to be learned, can't easily be described.

The link didn't work for me. Has it been moved? Nancy

Tree of heaven also has glands on the very back leaves that form notches...if you compaire your young leaf to a known sumac, if its a tree of haven it will have two distinct indents where the leaf starts to broaden after leaving the stem. Or you can bruse it, and if it smells like rotten peanuts then you know you have TOH.
Peace,
Nate

You are right. Access to that article cannot be had at the moment.
Here is what the PCA Alient Plant Working Group says:

NOTE: Correct identification of ailanthus is essential. Several native shrubs, like sumacs, and trees, like ash, black walnut and pecan, can be confused with ailanthus. Staghorn sumac (Rhus typhina), native to the eastern U.S., is distinguished from ailanthus by its fuzzy, reddish-brown branches and leaf stems, erect, red, fuzzy fruits, and leaflets with toothed margins.

http://www.themondaygarden.org/archives/2005/01/ailanthus_and_staghorn_sumac.html

That looks like the article that was relocated. I am also having trouble differentiating black walnut from tree of heaven. I guess I will just have them both taken out (there are two) because whatever they are, they are invasive and terrible.

The bark on black walnut should be noticeably different from tree of heaven. Tree of heaven has rather smooth bark, the walnut should be more furrowed.

Also that little "notch" on one side of the tree of heaven leaf is distinctive. Link below. Here is another {{gwi:1067897}}.

Here is a link that might be useful: {{gwi:1067899}}

Tree of heaven has a very smooth edge to the leaflet. It also has a notch at the base of eack leaflet. Black walnut has a serated edge to the leaves that are about like a butter knife. Sumac also has smooth margins on the leaflets but does not have the single ear or notch at the base. I have found the best way to kill the TOF is to drill holes in the wood slanting downward and fill them with weed killer. Do this every week for a month and it's a goner. Cut them live and you will have ten instead of one.
If you are still having trouble try this site it is great for identification, easy to use and lots of pictures!
http://www.oplin.org/tree/index.html

good post!

I agree, the notch at the base of the leaf and if you've ever been lucky enough to clear a field of trees of heaven you will NEVER EVER eat peanut butter again!!!!