If you have a much loved plant and discover that it is a threat to the environment or agriculture, in many cases there is no need to remove it, because there are often simple ways to prevent it reaching the bush or valuable farmland.
On the other hand, some plants that are invasive in the wild also behave badly in the backyard, creating a problem. Learning that the plant which is taking over is also an environmental or agricultural weed could be just the trigger you need to get rid of the menace.
Means of escape
Some garden plants can travel far. Birds eat the fleshy fruits and expel the seeds in their droppings at some distance. Rats, too, will carry away fruits such as olives, which have become weedy in parts of the southwest. Berries, seeds, bulbs or corms, and stem or root fragments drop into watercourses which transport them to lakes and swamps. Some seeds are wind-borne. One plume of pampas grass (Cortaderia selloana) may produce 100,000 seeds which can be blown up to 30 kilometres and give rise to large, dense stands of tussocks with razor-sharp leaves, such as along the upper Swan Valley.
As well as natural dispersal, human activities contribute greatly to spreading invasive plants. Pruned shoots might fall off a trailer carrying them to the tip and take root on the roadside. Aquatic plants dumped in a drain are easily washed into waterways where they can cover the water surface, starve the fish of oxygen and prevent recreational water sports. Unfortunately the deliberate dumping of garden waste is a major source of weeds and habitat degradation.