The Tree of Heaven, or Ailanthus altissima, is a deciduous tree species of moderate size, native to China. Its trunk and branches are usually grayish or cream colored in appearance. The tree's composite leaves are fairly large: dark green leaflets are arranged in uniform rows of 5 to 20 pairs that run down the opposing sides of each central vein.

Although the name alludes to a divine nature, some Davis residents are likely to complain that the tree "stinks to high heaven." All parts of the tree carry an unpleasant stench that some say is similar to that of rotting nuts or cat urine. In fact, the Chinese characters of the tree's Mandarin name, chouchun, literally mean "stinky plant."

As if this wasn't enough, this invasive species of tree has become more than a minor nuisance in parts of Yolo County. In addition to its ability to spread aggressively and grow rapidly, its roots have the power to push up sidewalks and break into underground infrastructure.