A small tree stands along a trail on the outskirts of town. Though it looks like an acacia tree, with its feathery leaves and yellow tufts of flowers, it’s actually Albizia lophantha. In both types of tree, the yellow tufts are actually composed of many threadlike stamens. But acacia has round balls-like flowers, each less than 1 centimeter across. Stink bean can be distinguished by its spike-like flowers that are about 2.5 centimeters across–and stamens that are united near the base.
This Australian native is also known as plume acacia, a nod to it’s more well-known cousin. It was probably introduced as an ornamental–and though it has spread into the wild, it hasn’t gone far and isn’t listed on California’s list of invasive plants. For this reason you’ll usually see it in “waste places”, the weedy ecological hinterlands that are on the edge of developed or heavily used places.