Tree of ..... Heaven?

~ by Julia Babb

If you drove through downtown Phoenix last week, you may have noticed that there is now a “bare spot” at the southeast corner of the fence between The Pollination Place and the Oregon Cheese Cave. “Didn’t there used to be a nice big tree there?” you may have asked yourself. “Perfectly good tree. Wonder why they cut it down.” Well, I wondered too, so I talked with Kristina Lefever, President of Pollinator Project Rogue Valley, to see if she could shed some light on why the tree was removed. She had one word for me: Invasive.

It seems you have to live with a tree to really know its character. The first summer after relocating to Main Street in 2019, Kristina was out gardening and noticed…well, a rather stinky smell. An odor, really, and none too pleasant! She identified the source as that tree, one Ailanthus altissima, also known as “Tree of Heaven,” probably for marketing reasons…in China (where it originated), it is more aptly known as chouchun, or 'foul smelling tree.’ (Yes, I’ll take one! Ha!)

This flowering ornamental tree is of the “pop-up” variety—a fast growing plant (3-6 feet a year for the first four years!) that prefers disturbed landscapes—thus favored by municipalities for its ability to provide shade quickly, and sure, they are nice-looking enough. Unfortunately, though, they really don’t pull their own weight, eco-systematically.

The flowers do attract pollinators, unfortunately: honey bees, flies (which like the ‘fetid’ smell) and some beetles, and one or two bird species might eat the berries. Otherwise, they don’t engage with the community of native species, except to take over; and in fact, they excrete a substance toxic to other species—plants AND people!

The first of its kind in America arrived in Philadelphia in the late 1700s, and grew in popularity so much that it was available at nurseries everywhere by 1840. Trivia Alert: It was the main metaphor in Betty Smith’s A Tree Grows in Brooklyn. Yes, A. altissima is that scrappy little tree! How ‘bout that?

The first specimens on the West Coast specifically were brought by Chinese Immigrants as they arrived to take part in the California Gold Rush in the 1850s. So many people planted Ailanthus altissima on their property that it inevitably “escaped cultivation” and became more or less an aggressive weed, an ecological bully. And not just in the Rogue Valley or the west coast—this is a global issue, with people in Australia and Europe dealing with it, too!

A. altissima has survived and spread by strategies other than pollination. Aside from their early favored status in cities and towns across America, its twin strategy—lots of seeds and super tenacious root systems—actually, I mean really determined and highly persistent root systems. So persistent in fact that the other (better) name is “Tree of Hell”. Eradication is difficult to put it weakly, and usually requires a persistent combination of hand pulling/cutting the suckers, and (sorry to say) maybe poison application.

Kristina had broached the subject of a 35-foot invasive tree on Main Street with the City of Phoenix, but since the tree was on private property, there was nothing they could do. The landowner (owner of the Phoenix Club) agreed that it should be taken out, but what about the cost? Then one day, Tom Doolittle visited The Pollination Place, and Kristina referenced the tree in rather unkindly language—and Tom offered to take it on! So, just last week, Tom appeared with the trusty assistance from friend Dave Maher, and down it came. (See photos below.) Ahhhh! Much better. Now the Pollinator Garden will get more sunlight, and less toxicity, too.

Now that the tree is down, we are on the watch for any headstrong roots that might start sending up seedlings so we can eradicate them at once. If you happen to have one of these feckless, heedless non-natives growing on your property, have mercy on our local ecosystem! I hear the wood makes a nice warming fire!

For more information than you ever knew you needed to know, refer to this data compiled by the USDA and US Forest Service. Enjoy!