A very widespread introduced species that is naturalised throughout large parts of Australia. It is most common in the southern and eastern parts of the country (i.e. it is widespread in Queensland, New South Wales, Victoria, Tasmania and South Australia and becoming more common in the south-western and southern parts of Western Australia). Also occasionally naturalised in the southern parts of the Northern Territory, sparingly naturalised in the ACT and naturalised on Norfolk Island.
Rapistrum rugosum is a species of flowering plant in the mustard family known by the common names annual bastardcabbage, common giant mustard or turnipweed. It is native to Eurasia and parts of Africa, and it is present throughout the world as an introduced species and a common 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 a raceme of flowers with dark-veined yellow petals that are each under a centimeter long. The fruit is a knoblike spherical ribbed silique borne on a long pedicel with a widened area where it joins the fruit.
This plant is useful.
How to get rid of:
- Hand pulling. It is relatively easy to pull individual plants from established populations of bastard cabbage. If you’ve got a small enough stand, get yanking. If you’ve got a big one, mobilize a pulling party with your neighbors. Just be sure you pull out the entire plant and do it before it goes to seed.
- Mowing. Mowing will remove some, but not all, flowers and reduce the amount of seed that could grow into a new plant next year. But mowing doesn’t remove all the seed stored in the ground.
- Herbicides. If it’s a dauntingly huge field, the harsh truth is that you might need to consider spraying with herbicides.