Weeds are plants growing in the wrong place. When weeds invade bushland, they threaten native plants, usually by out-competing them for light, nutrients and water. The result is the death of these native plants and often the disappearance of native animals, birds, insects and other creatures that depend upon them.
Although most environmental weeds come from other parts of the world, an Australian native plant growing out of its natural range can be just as devastating to local native species. Native weeds may flower earlier or more prolifically than a similar local species. If birds or insects feed on the new arrival they may not pollinate the local plants. This can cause a severe decline or loss of local native species.
For more information see:
Weeds.
The best way to control the spread of weeds is not to grow invasive weed species. Always be sure that a plant is a weed and not a native species.

Illustration by Kris Schaffer