Water hyacinth

Water hyacinth 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.

Another name for this plant is Eichhornia crassipes.

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

Water hyacinth - 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:

  • upright, free-floating aquatic plant
  • sometimes rooted in shallow water
  • perennial herb
  • grows to 60cm high.

Water hyacinth - habit

Stems and branches

These features can identify the stems and branches:

  • leaf stalks have a distinctive bulbous, inflated base that allows them to float on water
  • young plants have leaf stalks up to 25cm long
  • older plants have leaf stalks to 60cm long that are no longer inflated
  • roots are feathery, black to purple and up to 1m long
  • roots can be short if water is nutrient rich.

Water hyacinth - stems and branches

Leaves

These features can identify the leaves:

  • distinctive spoon shaped leaves
  • fleshy
  • shining vibrant green
  • in a basal rosette on dark green stems.

Water hyacinth - leaves

Flowers

These features can identify the flowers:

  • flower heads grow from the middle of rosettes
  • flowers are 5 to 35cm, bluish purple or white
  • flowers bloom from October to July.

Water hyacinth - flowers

Fruit and seeds

These features can identify the fruit and seeds:

  • water hyacinth can reproduce both vegetatively and through seeds
  • seeds are ovate-oblong, ribbed and about 1mm long
  • seed is viable for up to 20 years.

Water hyacinth - fruit and seeds

Similar looking plants

The following plant species look similar to water hyacinth:

There are four native species of aquatic plants in the genus Monochoria which look similar to water hyacinth. 

However, if you think you may have seen water hyacinth, or have this weed on your property, don't attempt to control it. 

Contact the Weeds Management Branch immediately for assistance.

Impact

Water hyacinth can have all of the following impacts:

  • aggressive invader of permanent freshwater bodies
  • can grow quickly to form large, dense mats over the water surface
  • infestations can double in size in a few weeks
  • a single plant can reproduce to cover 600m² in one year
  • can destroy freshwater wetlands and the native plants and animals that live in them
  • can block waterways and reduce water quality, increase water storage of dams and interfere with irrigation
  • can restrict recreational activities including swimming, boating and fishing
  • can create an environment that encourages mosquito breeding.

Habitat and distribution

Water hyacinth is native to Brazil, and was introduced into Australia in the 1890s as an ornamental plant for ponds and aquariums.

Established in coastal Queensland and New South Wales where it prefers fresh, static or slow flowing water with high organic content.

Six infestations have been recorded and eradicated in the Northern Territory (NT). 

There are currently no known establishments in the NT.

Control

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

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

Last updated: 27 June 2017