Tree of Heaven: The Invasive Tree Taking Over Our Hillsides
A few of us spotted this sapling pushing up through the mulch on a recent walk, and it's worth flagging: it's tree of heaven (Ailanthus altissima), one of the most aggressive invasive trees in our canyon. You can usually tell it apart from our native trees by its long compound leaves, each with a dozen or more smooth-edged leaflets, and by the strong, unpleasant smell the crushed leaves give off (some people compare it to rancid peanut butter).
Tree of heaven grows fast, spreads by both seed and root suckers, and releases chemicals into the soil that suppress the native plants around it. The biggest mistake people make is cutting one down on its own: without a follow-up herbicide treatment, a cut tree responds by sending up a thicket of new sprouts from its roots, sometimes fifty feet from the original trunk. That's why removal on parkland like ours needs to be coordinated with LA Recreation and Parks and done by a licensed applicator, not handled tree-by-tree by volunteers.
What you can do: if you spot a seedling like this one, small enough to hand-pull with its root intact, go ahead and pull it before it has a chance to establish. For anything larger, please don't cut it yourself — instead, note the location (a pin drop or photo helps) and let us know so we can add it to the list we're building for the next coordinated removal. The more eyes we have on this, the easier it is to keep it from spreading further into the canyon.
