Some of the worst weeds in California are substantial naturalized trees. The most famous of these is probably the Tasmanian blue gum (eucalyptus), which gets very big very fast, and crowds out other trees and plants in the process. The silver wattle, which is most commonly known locally by the Latin name Acacia dealbata, is even more voracious and prolific. It may seem simple enough to cut down an invading Acacia dealbata before it gets too big, but the seedlings from the original tree may continue to invade unrefined landscapes or wildlands for years afterward.
Even urban Acacia dealbata that lack space to disperse seed are problematic. After only about thirty years, they begin to deteriorate, but can die a slow unsightly death for another ten years! Deteriorating trees are likely to fall without much warning. They can get more than sixty feet tall, and typically fall intact, so can do considerable damage.
The only attribute of Acacia dealbatais that it can be so visually appealing. The somewhat gray, bi-pinnately compound foliage is very finely textured, and provides just enough shade without being too shady. (Bi-pinnately compound leaves are divided into smaller leaflets, which are also divided into even smaller leaflets.) Individual leaves are about three to five inches long. The fuzzy staminate (lacking petals) flowers that bloom in winter are so abundant that most of the foliage is obscured. The floral fragrance that is objectionable to some is appealing to others.