Eupatorium capillifolium (dogfennel) is a North American perennial herbaceous plant in the family sunflower family, native to the eastern and south-central United States. It is generally between 50 cm and 2 meters tall with several stems that fork from a substantial base. The stems and base are covered in leaves so dissected that they resemble branching green threads coming out of the stem in fractal patterns. When crushed, the leaves and flowers smell rather unpleasant.