Rapistrum rugosum is a species of flowering plant in the mustard family known by the common names annual bastard cabbage, common giant mustard or turnip weed. It is an invasive species in many areas. It is an annual herb producing an erect stem reaching up to about a meter tall. The leaves are variable in shape and size and the proximal blades are generally cut into lobes or divided into leaflets. The herbage is coated in rough hairs. The inflorescence is araceme of flowers with dark-veined yellow petals each under a centimetre long. The fruit is a knoblike spherical ribbed silique borne on a long pedicel with a widened area where it joins the fruit.