Water poppy (Hydrocleys nymphoides)

Water poppy is a perennial aquatic plant, found in still to slow moving water bodies up to 1 metre deep. It can form dense infestations that choke waterways.

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How does this weed affect you?

Water poppy can form dense infestations that choke waterways, impacting native fauna and flora. Heavy infestations can decrease the recreational value of waterways and worsen flooding. 

What does it look like?

Water poppy is a perennial aquatic water plant. Leaves and roots grow from nodes along the stem. Stems can be up to several metres long.

Leaves:

• dark green and shiny
• up to 12 cm across
• heart-shaped to round
• either float on the water surface or emerge up to 40 cm above the water. 

Flowers:

• have 3 petals
• yellow and poppy-like
• with a brownish-to-purple centre
• are 5-8 cm wide
• protrude above the water surface on stalks up to 30 cm long
• occur throughout summer.

Fruit:

• a capsule
• 15 mm long with a beak.

Seeds:

• are small (1 mm)
• horseshoe-shaped.

Where is it found?

Water poppy is native to Central and South America, and was introduced to Australia as an ornamental pond plant. It has become naturalised in parts of Australia, New Zealand, South Africa, Fiji, New Caledonia, French Polynesia, and several states in the south of the United States of America.

In New South Wales water poppy has naturalised at Coffs Harbour, the Central Coast, Albury and in the Port Hacking river in Sutherland shire. These infestations have been eradicated or are under control programs.

Maps and records

• Recorded presence of Water poppy during property inspections (Map: Biosecurity Information System - Weeds, 2017-2021)
  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.
  
  

How does it spread?

Water poppy spreads via stolons that take root in the soil at the nodes, and by the production of new plantlets that form and break away from the main plant.

What type of environment does it grow in?

Water poppy is mainly found in still to slow moving water bodies up to 1 metre deep. It grows best in full sun and in nutrient rich waterways but can tolerate cooler climates.

Acknowledgements

Author: Charlie Mifsud

Technical review: Rod Ensbey

References

Buhle Mthembu October 2011. Hydrocleys nymphoides weed alert South African National Biodiversity Institute (SANBI) 

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 2021 from: https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Hydrocleys~nymphoides

Sainty, G.R and Jacobs, S.W.L (1981). Water plants of New South Wales. Water Resources Commission of New South Wales.

New Zealand Weed Busters (nd). Water Poppy (Hydrocleys nymphoides) Weedbusters fact sheet. www.weedbusters.org.nz

More information

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Control

Herbicide options

See Using herbicides for more information.

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PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L (Only products registered for aquatic use)
Rate: One part product to 50 parts water
Comments: Spot spray
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate

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PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L (Only products registered for aquatic use)
Rate: One part product to 9 parts water
Comments: Splatter gun
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.
Greater Sydney Exclusion zone: All lands and waters in the region except for the core infestation area of the Hacking River catchment.	Regional Recommended Measure* Whole region:The plant should not be bought, sold, grown, carried or released into the environment. Exclusion zone: The plant should be eradicated from the land and the land kept free of the plant. Notify Local Control Authority if found. Core infestation: Land managers should mitigate the risk of new weeds being introduced to their land. Land managers should mitigate spread from their land.
Murray	Regional Recommended Measure* Land managers should mitigate the risk of new weeds being introduced to their land. The plant should not be bought, sold, grown, carried or released into the environment. Notify local control authority if found.
Riverina	Regional Recommended Measure* Land managers should mitigate the risk of the plant being introduced to their land. Land managers should mitigate spread from their land. Notify local control authority if found.
	*To see the Regional Strategic Weeds Management Plans containing demonstrated outcomes that fulfil the general biosecurity duty for this weed click here

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Reviewed 2019