Stunted ailanthus trees growing on a foundry waste dump, a hostile and arid environment. Ailanthus altissima is a tough and highly invasive tree from Asia. And now we have the unfortunate presence of the spotted lantern fly, for which the ailanthus is the preferred host. Ailanthus is often called sumac, but it is not. The actual sumacs are smaller valuable native trees that also have compound leaves.   Exposed in 2019, processed in 2021.