Cabomba

Cabomba is a declared Class A and Class C weed and a Weed of National Significance.

Go to the Weeds of National Significance website for more information.

Cabomba also has a statutory weed management plan (927.1 kb) which outlines the legal requirements for control.

Watch the Cabomba eradication program video.

If you think you may have seen cabomba, or have this weed on your property, don't attempt to control it. 

Contact the Weed Management Branch immediately for assistance.

Another name for this plant is Cabomba caroliniana.

Cabomba - infestation 

Identification

You should use this as a guide. There may be other plants or weeds that look similar. 

If you are unsure, contact the Weed Management Branch.

Habit

These features describe the habit of this plant:

  • an attractive aquatic plant formally used in fish tanks and ponds
  • mostly submerged plant, that grows to the surface to flower
  • 2 to 10 metres long and usually rooted to the water body floor.

Cabomba - habit 

Stems and branches

These features can identify the stems and branches:

  • branched stems
  • white or reddish brown hairs on stems
  • elongate and fragile
  • up to 0.4cm in diameter.

Cabomba - stems and branches 

Leaves

These features can identify the leaves:

  • two types of leaves (above and below water surface)
  • below the water surface opposite fan shaped leaves that grow on a 3 cm stem
  • above the water they have 2cm elliptical leaves.

Cabomba - leaves 

Flowers

These features can identify the flowers:

  • white/yellow
  • often a pink tinge on the tips
  • 2cm wide
  • form on short stems near or on the water’s surface
  • may be present all year in the Northern Territory (NT).

Cabomba - flowers 

Seeds

These features can identify the fruit and seeds:

  • can reproduce by seed
  • seeds are approximately 4mm long and 1mm wide
  • dark when mature
  • coated in gelatinous mucus.

Cabomba - fruit and seeds 

Similar looking plants

Hornwort (Ceratophyllum demersum) is a native water plant that looks similar to cabomba. You can tell them apart by looking at the leaf structure, however since cabomba poses such an extreme risk to the NT waterways you should always report any sighting that you think could possibly be cabomba. 

There is no harm in accidentally reporting hornwart. If you think you may have seen cabomba, or have this weed on your property, don't attempt to control it. Contact the Weeds Management Branch immediately for assistance.

Cabomba (left) beside hornwort (right) 

Cabomba (left) beside hornwort (right).

Impact

Cabomba can have all of the following impacts:

  • form dense populations very quickly
  • displace native plants
  • reduce water quality
  • decrease dissolved oxygen levels
  • restrict water flow
  • taint potable water supplies
  • increase irrigation and water supply costs.

Habitat and distribution

Cabomba is native to the Americas, but has been used extensively in the aquarium industry.

Discarded aquarium contents were probably the cause of the only two infestations in the NT, found in 1996 at Marlow Lagoon (eradicated) and in 2004 at Darwin River (persisting).

Cabomba likes to grow in slow moving or stagnant water bodies with silty soil.

This means that billabongs and floodplain areas would be highly susceptible to cabomba if it were to establish more widely in the NT.

Spread prevention 

Cabomba can reproduce and spread by the movement of small plant pieces and seeds. Anything that moves through affected water can sever cabomba's elongate and fragile stems. 

Broken stem fragments, as small as 1cm, and with only one pair of leaves, can take root and grow into new plants. Fishing lures, traps, and outboard motors can produce hundreds of fragments.

Given its historical use in the aquarium trade, positive cabomba identifications have been made in urban ponds and fish tanks. You must report suspected cabomba in these areas.

Cabomba - spread 

Darwin River Cabomba eradication program

The Northern Territory Government has been working to eradicate Cabomba (Cabomba caroliniana) from the Darwin River for more than a decade.

The infestation of Cabomba has now been reduced to less than one percent of its original size and activities have been intensified to finally remove cabomba from the Northern Territory.

The Cabomba Eradication Program includes three key activities:

  1. an integrated control program that includes large-scale treatment of cabomba using the aquatic herbicide, Shark™
  2. the establishment of a legislated quarantine zone in Darwin River between Cox Peninsula Road and Leonino Road to prevent weed spread
  3. powers to take legal action against any person or company that breaches the quarantine zone.

If you think you may have seen cabomba, or have this weed on your property, do not attempt to control it. Contact the Weed Management Branch immediately for assistance.

Cabomba is on the alert list for environmental weeds. This is a list of weeds that threaten biodiversity and cause other environmental damage.

Darwin River quarantine

A quarantine order (225.6 kb) is in place for cabomba affected areas of Darwin River between Cox Peninsula Road and Leonino Road until at least 21 November 2017. 

The quarantine prohibits the movement into or out of this section of river and the five metres of land adjacent to the water's edge. This includes:

  • people
  • objects
  • boats
  • vehicles
  • fishing equipment.

Vehicles are not to pass over causeways at Old Bynoe Road or Reedbeds Road if the river is flowing over these causeways.

Non permitted access into the quarantine zone may incur penalties in excess of $100,000 for individuals and in excess of $500,000 for a body corporate.

Last updated: 13 September 2017