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Home > Water Management > Water for the environment > Wetlands > Wetlands

Wetlands

The Water Weeds of NSW Wetlands

Save Our Waterways - "Learn to know it, Please don't grow it!"

 Introduction
 Impacts from water weeds
 Water Weeds of National Significance
 Other Water Weeds and their Legal Status in Australia
 Other Introduced Water Plants
 References and Further Reading

Introduction

Wetlands around NSW are under threat from infestations of water weeds. Water weeds are those plants that interfere with or have the potential to interfere with the values or uses of a waterbody. Water weeds require some form of action to reduce the impact they are having. Most of the plants that are considered to be water weeds in NSW have originated in other countries. However, if a plant is not indigenous to an area, even though it is a native, it may still become a pest by adversely impacting on the valuable resources of that area.

The legislation that concerns water weeds in Australia is the The Noxious Weeds Act 1993. This Act is administered in NSW by The Department of Agriculture.

Impacts of water weeds

Water weeds in our wetlands, creeks, rivers and dams can lead to serious negative economic, environmental and social impacts.

Impacts from water weeds include:

• Dangers to swimmers;
• Loss of fishing, boating and sailing areas;
• Destruction of native plants and animals;
• Increased drinking water treatment costs;
• Destruction of visually beautiful areas; and
• Increased costs to agricultural and forestry industries.

Water Weeds of National Significance

Australia's twenty worst weeds – Wanted Dead

The National Weeds Strategy was launched in 1997 in recognition of in increasing awareness of the threats caused by Australia's weeds. A list of Australia's 20 worst weeds was compiled as part of the strategy.

Of the 20 plants considered to be Australia's worst or most significant weeds, there are four that may be encountered in the aquatic environments of NSW. They are:

Alligator Weed - Alternanthera philoxeroides

A noxious weed in most parts of NSW. If found on land (or in water) the Local Control Authority must be notified and the weed must be fully and continuously suppressed and destroyed. Growth form is floating attached. Alligator weed is a native of South America.

Under the Noxious Weeds Act (1993) this plant:

MUST be controlled in: NSW, ACT, NT, Qld, SA, Vic, WA, Tas

Should not be introduced into: NSW, ACT, NT, Qld, SA, Vic, WA, Tas

MUST not be sold or grown in: NSW, ACT, NT, Qld, SA, Vic, WA, Tas

Cabomba / Fanwort – Cabomba caroliniana

A noxious weed in NSW. If found, the Local Council must be informed.

Under the Noxious Weeds Act (1993) this plant:

MUST be controlled in: NSW, NT, Qld, WA, Tas

Should not be introduced into: NT, WA, Tas

MUST not be sold or grown in: NSW, NT, Qld, WA, Tas

Salvinia - Salvinia molesta

A noxious weed in most parts of NSW. If found on land (or in water) the Local Control Authority must be notified and the weed must be fully and continuously suppressed and destroyed. Growth form is floating. A native of southern Brazil.

Under the Noxious Weeds Act (1993) this plant:

MUST be controlled in: NSW, NT, Qld, SA, Vic, WA, Tas

Should not be introduced into: NT, SA, Vic, WA, Tas

MUST not be sold or grown in: NSW, ACT, NT, Qld, SA, Vic, WA, Tas

Willows (Salix spp. except Salix babylonica, S. X calodendron and S. X. reichardtii)

A noxious weed in most parts of NSW. For specific declarations within the Shires of NSW, contact the NSW Department of Agriculture.

This information has been adapted from:

1. The "Weeds of National Significance Poster" - produced as part of the National Weeds Strategy
2. The Weeds Australia Website; and
3. Information supplied by Mike Boulton, DLWC, Dubbo.

Other Water Weeds and their Legal Status under the Noxious Weeds Act (1993)

The following is a list of some of the other significant aquatic weeds that may be encountered in the wetlands of NSW.

Senegal Tea Plant - Gymnocoronis spilanthoides

Source: Sainty & Assoc.

A noxious weed in most parts of NSW. If found on land (or in water) the Local Control Authority must be notified and the weed must be fully and continuously suppressed and destroyed.

Under the Noxious Weeds Act (1993) this plant:

MUST be controlled in: NSW, Act, Qld, WA, Tas, NT

Should not be introduced into: NSW, ACT, WA, Tas, SA, NT

MUST not be sold or grown in: NSW, Act, Qld, WA, Tas, SA, NT

Largarosiphon - Largarosiphon major

Source: Sainty & Assoc.

A submerged plant that is a native of Zimbabwe and South Africa.

A noxious weed in most parts of NSW. If found on land (or in water) the Local Control Authority must be notified and the weed must be fully and continuously suppressed and destroyed.

Under the Noxious Weeds Act (1993) this plant:

MUST be controlled in: NSW, ACT, NT, Qld, SA, Vic, WA, Tas

Should not be introduced into: NSW, ACT, Qld, SA, Vic, WA, Tas

MUST not be sold or grown in: NSW, ACT, Qld, SA, Vic, WA, Tas

Water Lettuce - Pistia stratiotes

Source: Sainty & Assoc.

A noxious weed in most parts of NSW. If found on land (or in water) the Local Control Authority must be notified and the weed must be fully and continuously suppressed and destroyed.

Under the Noxious Weeds Act (1993) this plant:

MUST be controlled in: NSW, Act, Qld, WA, Tas, NT

Should not be introduced into: NSW, Act, WA, Tas, SA, NT

MUST not be sold or grown in: NSW, Act, Qld, WA, Tas, SA, NT

Water Hyacinth - Eichhornia crassipes

Source: T. Anderson

A noxious weed in most parts of NSW. If found on land (or in water) the Local Control Authority must be notified and the weed must be fully and continuously suppressed and destroyed. A free-floating plant, with lilac-blue flowers.

Under the Noxious Weeds Act (1993) this plant:

MUST be controlled in: NSW, ACT, NT, Qld, SA, Vic, WA, Tas

Should not be introduced into: ACT, NT, SA, Vic, WA, Tas

MUST not be sold or grown in: NSW, ACT, NT, Qld, SA, Vic, WA, Tas

Ludwigia, Peruvian Primrose - Ludwigia peruviana

Source: Sainty & Assoc.

The weed must be fully and continuously suppressed and destroyed. Declaration applies to a minority of local government areas of the State.

Under the Noxious Weeds Act (1993) this plant:

MUST be controlled in: NSW, QLD, SA

Should not be introduced into: QLD, WA, SA

MUST not be sold or grown in: NSW,  QLD, SA

Horsetails - Equisetum arvense

Source: Sainty & Assoc.

A noxious weed in most parts of NSW. If found on land (or in water) the Local Control Authority must be notified and the weed must be fully and continuously suppressed and destroyed.

Under the Noxious Weeds Act (1993) this plant:

MUST be controlled in: NSW, ACT, Qld, SA, Tas, WA

Should not be introduced into: NSW,  ACT, Qld, SA, Tas

Must not be sold or grown in: NSW, ACT, Qld, SA, Tas

Several other waterweeds have been declared noxious in other parts of Australia, other than NSW. Some of these plants must still not be introduced anywhere in Australia. They are:

Water Caltrope - Trapa natans

Source: S. Jacobs

Legal status in Australia under the Noxious Weeds Act (1993):

MUST be controlled in: Qld

Should not be introduced into: Australia

MUST not be sold or grown in: Qld

Eurasian Watermilfoil - Myriophyllum spicatum

Source: Sainty & Assoc.

Legal status in Australia under the Noxious Weeds Act (1993):

MUST be controlled in: Qld

Should not be introduced into: Australia

MUST not be sold or grown in: Qld

Water Soldier - Stratiotes aloides

Source: C. Cook ("Water Plants in Australia")

Growth form is floating.

Legal status in Australia under the Noxious Weeds Act (1993):

Should not be introduced into: Australia

Arrowhead / Sagittaria - Sagittaria montevidensis

Source: Sainty & Assoc.

Legal status in Australia under the Noxious Weeds Act (1993):

MUST be controlled in: WA, SA, Tas

Should not be introduced into: WA, SA, Tas

MUST not be sold or grown in: WA, SA, Tas, QLD

Hornwort - Ceratophyllum demersum

Legal status in Australia under the Noxious Weeds Act (1993):

MUST be controlled in: Tas

Should not be introduced into: Tas

MUST not be sold or grown in: Tas

Leafy Elodea / Dense Waterweed - Egeria densa or Elodea densa

Source: Norbert Haley

Legal status in Australia under the Noxious Weeds Act (1993):

MUST be controlled in: WA, SA, Tas

Should not be introduced into: WA, SA, Tas

Must not be sold or grown in: WA, SA, Tas, NT

Elodea / Canadian Pondweed - Elodea canadensis

Source: Sainty & Assoc.

A submerged water weed.

Legal status in Australia under the Noxious Weeds Act (1993):

MUST be controlled in: WA, SA, Tas, NT

Should not be introduced into: WA, SA, Tas, NT

MUST not be sold or grown in: WA, SA, Tas, NT

Hydrilla - Hydrilla verticillata

Source: University of Florida

Legal status in Australia under the Noxious Weeds Act (1993):

MUST be controlled in: Tas

Should not be introduced into: Tas, WA

MUST not be sold or grown in: Tas

Hydrocotyl - Hydrocotyl ranunculoides

Source: Sainty & Assoc.

Legal status in Australia under the Noxious Weeds Act (1993):

MUST be controlled in: SA, WA

MUST not be introduced into: SA, WA

Must not be sold or grown in: SA, WA

Brazilian Watermilfoil - Myriophyllum aquaticum

Source: Sainty & Assoc.

Also commonly called Parrots Feather or Threads of Life.

Legal status in Australia under the Noxious Weeds Act (1993):

MUST be controlled in: Tas, WA

Should not be introduced into: Tas, WA

MUST not be sold or grown in: Tas, WA

Sagittaria, Arrowhead - Sagittaria platyphylla or Sagittaria graminea ssp. platyphylla

Source: Norbert Haley

Legal status in Australia under the Noxious Weeds Act (1993):

MUST be controlled in: SA, Tas, WA

Should not be introduced into: SA, Tas, WA

MUST not be sold or grown in: SA, Tas, WA

This information has been adapted from:

1. "Save our Waterweeds Poster" - produced by the Weed Management Section, Department of Primary Industries, Water and Environment, Tasmania;

2. The Weeds Australia Website; and

3. Information supplied by Mike Boulton, DLWC, Dubbo.

Other Introduced Water Plants

The following is a list of some of the other introduced water plants that may be encountered in the wetlands of NSW. These plants are not currently declared as noxious under the Noxious Weeds Act 1993, but they still have the potential to interfere with the values or uses of waterbodies in NSW.

Umbrella Sedge - Cyperus eragrostis

An emergent sedge that is actually native to America. Although this sedge is an introduced plant it does actually provide habitat to a variety of wetland animals.

Barnyard Grass - Echinochloa crus-galli

An introduced emergent plant.

Weeping Willow - Salix babylonica

The weeping willow is a tree that tolerates some flooding. A native of Europe, but introduced from China. Has very characteristic weeping branches. It has been used widely throughout NSW as a cheap and effective method of providing erosion control. However, this practise is now discouraged. Natives trees are recommended as an alternative.

Yellow Waterlily - Nymphaea mexicana

The yellow waterlily has floating leaves and bright yellow flowers. Once established it can be very difficult to eradicate.

References and Further Reading

Reference Websites:

The National Weeds Strategy Website

The New South Wales Weed Strategy - NSW Agriculture

You can also find out about the weeds mentioned on these pages and other waterweeds in NSW by contacting New South Wales Agriculture on 1800 680 244.

Sainty, G. R. and Jacobs, S.W.L. (1981) Waterplants of New South Wales. Water Resources Commission, Sydney.

Sainty, G. R. and Jacobs, S.W.L. (1994) Waterplants in Australia. Edn. 3. Sainty and Associates, Sydney.