Amazon frogbit

• This perennial floating aquatic plant can grow up to 50cm tall.
• Leaves are bright green and up to 4cm wide. They are either floating or emergent and are arranged in basal rosettes along runners (stolons).
• Flowers are white to pale yellow, male or female, and up to 13mm wide.
• Flowers emerge upright, and subsequent fruit develop on the underside of the plant, in the water. Both fruit and flowers are hard to see.
• Fruit are 4–13mm long and 2–5mm wide. Each contains up to 100 highly viable seeds, which are less than 1mm diameter and spherical with a rough surface.
• Fruit are retained on the plant but split when mature, releasing seeds, which mostly sink.

3D model

• View the 3D model to help you identify this plant. You can magnify the image and manipulate the view to inspect the plant from every angle.

• Prefers tropical to subtropical climates.

• The first detection of Amazon frogbit in the Queensland environment was in March 2011. Established plants were found in a Redlands waterway adjoining an urban area.
• This plant has been sold as an aquarium plant for some time. It is likely that its distribution in waterways near urban areas throughout Queensland is a result of escapes or releases from aquariums or garden water features.
• It has also been detected in Gold Coast and Sunshine Coast waterways and a major infestation has occurred in the Barron River catchment in North Queensland.
• This plant is also found in other rivers and creeks. It may become naturalised in dams, lakes and freshwater wetlands throughout Queensland.

• Seed banks can exist in soil for at least 3 years.
• Plants grow from seed and through vegetative reproduction, which is the most important method of propagation.

Environmental

• Forms dense mats that smother native aquatic plants.
• Reduces oxygenation of water.

Economic

• Interferes with watercraft when infestations are large.
• Degrades quality of swimming and fishing.
• Interferes with infrastructure used for water treatment, water management and hydroelectricity (such as on the Barron River).

• Spreads by seeds and stem fragments. Floating rosettes produce runners (stolons), the ends of which grow into juvenile plants.
• Can also be spread by careless dumping of unwanted plants into urban drains leading into waterways. Young plants can easily and quickly be carried along by water.

• Find out how farmers can prevent weed spread.
• Find out how gardeners and outdoor enthusiasts can prevent weed spread.

• The best approach is to combine herbicide and physical control methods. The control methods should suit the specific plant and particular situation.

Physical control

• Remove plants in ponds or small dams by physical or mechanical means, taking care to remove all root mass. Apply follow-up herbicide treatment.

Herbicide control

• The Australian Pesticides and Veterinary Medicines Authority has registered a herbicide for the control of Amazon frogbit in Queensland.
• Read the Amazon frogbit fact sheet for herbicide control and application rates.

• Amazon frogbit is not a prohibited or restricted invasive plant under the Biosecurity Act 2014. However, by law, you have a general biosecurity obligation to take reasonable and practical measures that are under your control to minimise the biosecurity risks associated with invasive plants.
• Each local government must have a biosecurity plan that covers invasive plants in their area. This plan may include actions to be taken on Amazon frogbit. Some of these actions may be required under local laws. Contact your local government for more information.