Mugwort is also called wild chrysanthemum because of the shape of the lower leaves. The plant is a perennial that spreads rapidly by rhizomes. It is one of the most severe weeds of the nursery and landscape plantings. It, along with Japanese knotweed (bamboo), is rapidly becoming one of our worst roadside weeds because people dig it out of their plantings and drop it along side the road. CASORON should be used to control it wherever possible. The white wooly underside of the leaf is a good ID characteristic and is visible even in the winter. It is a relative of dusty miller.