Dense waterweed
Egeria densa
family
Hydrocharitaceae
origin
Exotic
declaration
Council Pest Vegetation (BCC Natural Asset Local Law)
Council Pest Vegetation (BCC Natural Asset Local Law)
Common names
Anacharis, Argentinian waterweed, Brazillian elodea, Ditch moss, Water thyme.
A very leafy aquatic plant that grows almost entirely underwater. Its stems (up to 5 m long) are usually anchored to the substrate, but can sometimes be free-floating at the water surface. Its partially see-through and strap-like leaves densely clustered along stems in groups of 3-7. its white flowers are borne just above the water surface and have three broad petals (9-12 mm long). It only reproduces vegetatively in Australia, via stem fragments.
Impact
Impact
Dense waterweed (Egeria densa) is regarded as an environmental weed in Queensland, New South Wales, Victoria, South Australia, Western Australia and Tasmania. It is also seen as a potential environmental weed in the Northern Territory. It produces dense underwater mats that block light penetration and compete with, and often almost completely displace, native plants. It also depletes oxygen levels and otherwise changes the character of invaded waterways and waterbodies. This can also adversely affect the available habitat for fish and waterfowl.In south-eastern Queensland, where this species is very common in waterways, it is ranked among the top 50 most invasive plant species. It is also widespread in New South Wales, and has become the dominant water plant along about 150 kilometres of the Hawkesbury-Nepean River system. It is also listed as an invasive garden plant in the Greater Adelaide Region, is an aquatic wetland weed in southern Western Australia, and is regarded as a serious threat to one or more vegetation formations in Victoria. Dense waterweed (Egeria densa) is highly invasive in the USA, where it forms dense monospecific surface mats that restrict water movement, trap sediment, and cause fluctuations in water quality. In New Zealand, it has also been observed to rapidly re-colonise de-vegetated waterways following floods.
Location
Location
Characteristics
Characteristics
Similar Species
Similar Species
Dense waterweed (Egeria densa) is regarded as an environmental weed in Queensland, New South Wales, Victoria, South Australia, Western Australia and Tasmania. It is also seen as a potential environmental weed in the Northern Territory. It produces dense underwater mats that block light penetration and compete with, and often almost completely displace, native plants. It also depletes oxygen levels and otherwise changes the character of invaded waterways and waterbodies. This can also adversely affect the available habitat for fish and waterfowl.In south-eastern Queensland, where this species is very common in waterways, it is ranked among the top 50 most invasive plant species. It is also widespread in New South Wales, and has become the dominant water plant along about 150 kilometres of the Hawkesbury-Nepean River system. It is also listed as an invasive garden plant in the Greater Adelaide Region, is an aquatic wetland weed in southern Western Australia, and is regarded as a serious threat to one or more vegetation formations in Victoria. Dense waterweed (Egeria densa) is highly invasive in the USA, where it forms dense monospecific surface mats that restrict water movement, trap sediment, and cause fluctuations in water quality. In New Zealand, it has also been observed to rapidly re-colonise de-vegetated waterways following floods.
