Bidens pilosa

The leaves are oppositely arranged and range from simple to pinnate in form, the upper leaves with three to five dentate, ovate to lanceolate leaflets. The petioles are slightly winged. The inflorescence is a small capitulum borne on relativel ylong peduncles. The inflorescence consist of about four or five broad white ray florets (ligules), surrounding many tubular yellow disc florets without ligules that develop into barbed fruits (achenes). The fruits are slightly curved,stiff, rough black rods, tetragonal in cross section, about 1 cm long, typically with two to three stiff, heavily barbed awns at their distal ends.The barbed spines of the achenes get stuck in the feathers, fur, fleeces,clothing, etc. of people or animals that brush against the plant. The plant has a short life cycle, completing its growth and reproduction within a single year.