Mexican poppy (Argemone ochroleuca subsp. ochroleuca)

Mexican poppy is a small plant with spiky leaves and bright yellow flowers. It is poisonous to livestock and people.


How does this weed affect you?

Mexican poppy is poisonous to stock and humans, but is rarely eaten by stock due to its unpalatable bitter yellow sap. Contamination of stock feed with seeds of Mexican poppy may result in poisoning. It also can invade crops such as sugarcane, cereals and vegetables. 

What does it look like?

Mexican poppy is an erect annual herb growing up to 1.5 m high.

The leaves are alternate, irregularly lobed and up to 12 cm long. They are bluish green or greyish green with white mottling and have small yellow spines at the end of each lobe. Flowers are cream to pale yellow with 6 petals and are 3 - 7 cm in diameter. The fruit is an oval or oblong shaped capsule 2 - 4 cm long with numerous spines. 

Similar looking plants

American poppy Argemone subfusiformis is very similar looking. It has brighter yellow flowers and the capsule has fewer larger spines. 

Scientific name change

This species was previously named Argemone mexicana. 

Where is it found?

Mexican poppy can grow in a wide variety of climates from semiarid to wetter subtropical climates. It tolerates a wide variety of soil types and can grow well in soils with low nutrient levels. It has been found in the far western parts of NSW to the coast and from the Queensland to Victorian borders. 

Mexican poppy is native to Mexico.

How does it spread?

Seeds can be spread in water, mud, fodder and grain, and on machinery.


Parsons, W.T., & Cuthbertson, E. G. (2001). Noxious weeds of Australia. CSIRO publishing.

PlantNET (The NSW Plant Information Network System). Royal Botanic Gardens and Domain Trust, Sydney. Retrieved 16 March 2021 from:

More information

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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.

2,4-D LV ester 680g/L (Estercide® Xtra)
Rate: 800 mL to 1.15 L per ha
Comments: Pastures (non legumes), rights of way and industrial areas.
Withholding period: Do not graze or cut for stock food for 7 days after application.
Herbicide group: 4 (previously group I), Disruptors of plant cell growth (Auxin mimics)
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 pest 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.

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For technical advice and assistance with identification please contact your local council weeds officer.

Reviewed 2018