Weeds of National Significance
Department of the Environment and Heritage and the CRC for Australian Weed Management, 2003
ISBN 1 9209 3218 6
About the guide
Most species of willow are Weeds of National Significance. They are among the worst weeds in Australia because of their invasiveness, potential for spread, and economic and environmental impacts. They have invaded riverbanks and wetlands in temperate Australia, occupying thousands of kilometres of streams and numerous wetland areas.
Unlike most other vegetation, willows spread their roots into the bed of a watercourse, slowing the flow of water and reducing aeration. They form thickets which divert water outside the main watercourse or channel, causing flooding and erosion where the creek banks are vulnerable. Willow leaves create a flush of organic matter when they drop in autumn, reducing water quality and available oxygen, and directly threatening aquatic plants and animals. This, together with the amount of water willows use, damages stream health.
The replacement of native vegetation (eg river red gums) by willows reduces habitat (eg nesting hollows, snags) for both land and aquatic animals.
Millions of dollars are spent each year on willow control in southeastern Australia using chemical and/or mechanical techniques. In Victoria alone, the cost of willow management is about $2 million annually.
Weeping willow S. babylonica, and two hybrid species of pussy willow S. x calodendron and S. x reichardtii, are not Weeds of National Significance. Nevertheless, these species are of concern because they can hybridise with other species that would otherwise not produce seeds, so they should not be planted near other willows.
For information about national willow management please contact:
|Extent in Australia||Potential distribution|
|NSW, VIC, ACT||Could further expand in current locations; plus SA, TAS|