The Problem with Tree of Heaven
Tree of heaven sounds like it must be a great tree, right? It came from China where it grew on steep, rocky ground, often at the tops of mountains, pointing towards the heavens. Introduced to Philadelphia in 1748 by a gardener, the tree was popular because it grew rapidly in urban areas and had few pests or diseases. The problem is that the tree quickly forms dense colonies connected by underground roots. The trees release chemicals from their roots and leaves that prevent other plants from growing. The aggressive roots can damage building foundations and underground pipes.
Photo courtesy of the Missouri Botanical Garden PlantFinder