Anchored water hyacinth (Eichhornia azurea)

PROHIBITED MATTER: If you see this plant report it. Call the NSW DPI Biosecurity Helpline 1800 680 244

Anchored water hyacinth is an aquatic plant that forms dense mats in and across the surface of water bodies.


How does this weed affect you?

Anchored water hyacinth is an aquatic plant that forms dense mats in and across the surface of water bodies. It can invade still or slow-moving bodies of fresh water such as wetlands, dams and irrigation channels, and mud along river and creek banks.

Anchored water hyacinth can form a smothering mass of plant material in the water column and over the surface of a water body, having detrimental impacts on environmental, aesthetic and recreational values, and obstructing irrigation and navigation. The floating weed masses also harbour mosquitoes and can contribute to water loss through transpiration.

Anchored water hyacinth looks similar and is closely related to water hyacinth (Eichhornia crassipes), that does occur in waterways in eastern Australia and New South Wales (NSW).

Where is it found?

Anchored water hyacinth is a native plant of Mexico, Central America, South America and Jamaica. It is currently found throughout Africa and parts of Texas, where it has been declared as a noxious weed and is the subject of active eradication campaigns. Due to the worldwide weed status of its close relative water hyacinth, anchored water hyacinth is a prohibited plant in many countries.

Anchored water hyacinth is not currently known to occur in NSW. In 2005 it was removed from a retail outlet in northern Sydney, but has not been reported since. It is prohibited from importation into Australia.

Maps and records

  • Recorded presence of Anchored water hyacinth during property inspections (Map: Biosecurity Information System - Weeds, 2017-2020)
    These records are made by authorised officers during property inspections under the Biosecurity Act 2015. Officers record the presence of priority weeds in their council area and provide this to the NSW Department of Primary Industries. Records reflect the presence of the weed on the date of inspection.

  • Estimated distribution of Anchored water hyacinth in NSW (Map: NSW Noxious Weed Local Control Authorities, 2010)
    Map shows weed distribution and density estimated by local council weeds officers in 2010.

How does it spread?

Anchored water hyacinth is able to reproduce both vegetatively (when new daughter plants grow from the stems of the parent plant) and by seed. Infestations spread when daughter plants or pieces of stem break away and move downstream. Whole sections of an infestation can break off and move during floods and periods of high water flow.

Flowering occurs in summer and autumn and seeds can be carried in water and mud, on vehicles and by birds. Seeds germinate in spring.

In countries where anchored water hyacinth is an established weed, humans have contributed to spread by growing it as an ornamental plant in ponds or aquariums and dumping unwanted plants in or near waterways.

What does it look like?

Anchored water hyacinth can be distinguished from water hyacinth by its petioles (leaf stalks) which are slender - not inflated like the stems of water hyacinth.

Submerged stems are smooth and branched. Flowering stems are erect and stand 8–12 cm above the water.

Emergent leaves are variable in size, generally very rounded in shape, 5–16 cm long and 2–16 cm wide. Leaves growing below the water or in heavily shaded areas become elongated, between 6 and 20 cm long and about 1 cm wide.

Flowers are in spikes with several flowers along a hairy stem. The flowers are funnel-shaped with six toothed petals 1–3 cm long. The flowers are mostly white or lavender blue with deep purple centres. The uppermost petal has a distinct yellow spot. Individual flowers open for one day only.

Seeds are small and only 1–2 mm long.

Anchored water hyacinth is also similar to the native plant Monochoria cyanea - a subtropical species rarely found in NSW. In comparison anchored water hyacinth has larger flowers, a longer and denser flower head, a yellow spot on the uppermost petal, and more rounded leaves.

What type of environment does it grow in?

Anchored water hyacinth usually grows rooted in mud or clay beneath the water, and can reach the surface even when rooted at depths of up to 10–15 metres. It can also survive free-floating.


2006 edition prepared by Annie Johnson; 2012 edition reviewed by Rod Ensbey; Edited and prepared by Elissa van Oosterhout.


Department of the Environment (2011) Weeds in Australia, Eichhornia azura, Australian Government. Available at

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Please do not attempt to treat or dispose of this weed yourself. Report this plant if you see it anywhere in NSW by calling the helpline listed at the top of this page immediately.

NSW DPI will lead an initial response for the treatment and disposal of the plant to stop it from spreading

Herbicide options

Users of agricultural or veterinary chemical products must always read the label and any permit, before using the product, and strictly comply with the directions on the label and the conditions of any permit. Users are not absolved from compliance with the directions on the label or the conditions of the permit by reason of any statement made or not made in this information. To view permits or product labels go to the Australian Pesticides and Veterinary Medicines Authority website

See Using herbicides for more information.

PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L (Only products registered for aquatic use)
Rate: Up to 200 mL in 10 L of water
Comments: Spot spray application
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate

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Biosecurity duty

The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.

Area Duty
All of NSW General Biosecurity Duty
All plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable.
All of NSW Prohibited Matter
A person who deals with prohibited matter or a carrier of prohibited matter is guilty of an offence. A person who becomes aware of or suspects the presence of prohibited matter must immediately notify the Department of Primary Industries

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For technical advice and assistance with identification please contact your local council weeds officer.
For further information call the NSW DPI Biosecurity Helpline on 1800 680 244 or send an email to

Reviewed 2018