Dog fennel

Eupatorium capillifolium

Dogfennel growth frequently occurs from overwintering rosettes, but seeds will also sprout and grow when soil temperatures reach 65 F. The growth will generally consist of a single, non-branching shoot that can exceed 8 feet in height. The leaves are very thin and emit a strong odor when crushed.
Seeds are surrounded with hairs (similar to dandelion), allowing effective dispersal by wind. Therefore, bare areas in pastures are ideal environments for windblown seed to become established.
In addition to growth from seed, dogfennel can spread from underground rootstocks. These rootstocks arise from the main taproot and grow laterally in all directions. This process will result in the production of distinct plant colonies in only three years.