A weed is any plant out of place.
Environmental Weeds
Environmental weeds are plants that represent a threat to the conservation values of natural ecosystems. They invade native plant communities and out-compete them causing a reduction in plant diversity and resulting in a loss of habitat for native animals.
Some examples of environmental weeds are bridal creeper, bitou bush, boneseed, blackberry and lantana.
Environmental weeds can also be native Australian plants that are not local (indigenous) to the area they are growing in. They have the potential to displace and out-compete plants within the local plant community. Examples of native Australian plants that are doing this are sweet pittosporum and coast wattle.
Noxious Weeds
Some serious weeds are required by law to be controlled by all landholders in an area. These are known as noxious weeds and the law that controls these in NSW is the Noxious Weeds Act 1993.
Weeds that are declared noxious are those weeds that have the potential to cause harm to the community and individuals, can be controlled by reasonable means and most importantly, have the potential to spread within an area and to other areas.
A weed is declared noxious because its control will provide a benefit to the community over and above the cost of implementing control programs.
The Noxious Weeds Act 1993 classifies weeds into numbered control classes, each of which require a different level of control. The Act requires that 'the growth and spread of Class 4 weeds must be controlled according to the measures specified in a management plan published by the local control authority'. For land within a local government area, the Council is the local control authority.
The Management Plan for Class 4 weeds in the Rockdale City Council area includes Serrated Tussock, Rhus Tree, St John’s Wort, Prickly Pear, Privet, Asthma Weed, Blackberry, Camphor Laurel, Castor Oil Plant, Chilean Needle Grass, Harrisia Cactus and Lantana.
Duckweed at Bicentennial Ponds
During the summer months duckweed does occur at Bicentennial Ponds. This plant floats on the water surface in a bright green layer.
This weed is a native plant and appears in waterways when there is the presence of excess nutrients.
Duckweed is non toxic and is a food source for many animals that live within the wetlands. Its main benefit, however, is its ability to remove excess nutrients from the water - a common problem for urban waterways.
Research has also found that duckweed prevents a number of noxious weeds from growing in our waterways, for example, blue green algae.
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