Amazon Frogbit

Other Common Names: Smooth frogbit, West Indian spongeplant. 

Synonyms: ​​Limnobium laevigatum​, Salvinia laevigata.

Reaches maturity in approximately 6 to 12 weeks and grows up to 0.6 m tall. Seeds can remain viable in the soil seedbank for 3 to 4 years.

• Fleshy, berry‑like capsules.
• About up to 13 mm long and up to 5 mm in diameter.
• Each capsule can contain up to about 100 seeds.
• Seeds are about 1 mm long, slightly flattened and covered with fine hairs.

Can be observed in still or slow flowing freshwater ponds, lakes, swamps, drains, canals and rivers as a floating plant. Prefers high light and nutrient-rich, muddy substrates.

​​Spread by seeds and stem fragments. Seeds are germinated underwater then float to the surface, while floating rosettes produce stolons to regenerate new plants. Both floating rosettes and seeds are light so can be easily dispersed by water. Also spread by illegal dumping of the unwanted aquarium plants into waterbodies.​

• Forms dense mats across the water surface.
• Outcompetes native aquatic plants.
• Reduces light, food and shelter for fish and other aquatic animals.
• Blocks waterways, drains and irrigation channels.
• Creates safety hazards by hiding open water and making it look like solid ground.
• Interferes with commercial and recreational use of freshwater systems.
• Increases suitable habitat for mosquitoes.
• Prevents light and gas exchange in the water column, degrading water quality.
• Rapid vegetative growth enables complete coverage of water bodies.

It was initially sold as an ornamental aquatic plant in Australia. Due to its invasive nature, it quickly became widespread across Australia through waterways due to illegal dumping of plants from aquariums or garden water. 

Detected in 2013 at Cannington for the first time in Western Australia. Several severe infestations have been successfuly eradicated in the State. However there are other persistent infestations which are still being managed.