Native to South Africa, oncosiphon pilulifer
has become established in two main areas of the US, from San Diego to Los Angeles in California, and the Greater Phoenix area in Arizona; it is classed as invasive. Its common name, stinknet, references the strong, unpleasant odor of all parts of the plant.
Plants produce several stems, branching from the base. Leaves are finely divided into narrow, linear, gland-dotted lobes, finely hairy. The inflorescence is a small cluster, of up to four globular yellow flowerheads, about a third of an inch across, which contain disc florets only. Flowerheads are attached by slender stalks around one inch in length, lacking any bracts.