Salvinia (Salvinia molesta) is a State prohibited weed.

Handful of salvinia

If you find salvinia

If you think you may have seen salvinia, please contact us by:

Please do not attempt to treat or dispose of this weed yourself. We will treat, remove and dispose of salvinia safely, at no cost to the land owner.

Why you must report salvinia

Salvinia originated in South America and is a problematic weed in:

  • North America
  • Hawaii
  • Philippines
  • South East Asia
  • PNG
  • India
  • Africa
  • New Zealand

In Australia it is declared as a prohibited weed in all States and Territories.

Salvinia was introduced to Australia as an ornamental, aquarium plant. It has since been found in waterways in QLD, NSW, NT, WA and in isolated open waterways in Victoria.

Salvinia has prolific growth in nutrient rich water when water temperatures are between 20 to 30°C. Dams can be completely covered by salvinia in one growing season. Therefore it is critical that an effective eradication program be implemented as soon as an infestation is discovered, to prevent linked open water systems from becoming infested, and eradication less viable.

Salvinia is a floating fern that can quickly form dense mats and completely cover the water surface by doubling in biomass every few days when conditions are suitable. With this rapid growth, it can block waterways, impede irrigation and prevent recreational activities and impact water quality, resulting in the loss of native flora and fauna.

This is salvinia.

Salvinia has two kinds of leaves one floating and the other submerged. The floating leaves are green oval shaped and covered in waxy hairs which make the leaves water repellent.

The leaf shape varies depending on how crowded the plants are and the growth stage that it is in.

For a crowded plant the leaves are oblong and deeply folded together.

Isolated plants lie flat on the water surface.

Submerged leaves act and look like roots. There is no true root system.

Salvinia has been found in waterways, garden ponds, dams and for sale illegally at markets and online.

Dense mat of salvinia

Water repellent leaves of salvinia

 Salvinia leaves floating on the water

Root-like leaves

Lookalike species

Azolla plants (Azolla spp.) are also small, floating, perennial ferns with long free hanging roots, that are commonly mistaken for salvinia. The key difference is in the leaf shape and colour. Azolla has triangular shaped leaves that become red in colour when exposed to high levels of sunlight.

Salvinia identification

Salvinia molesta is the only recorded species of salvinia present in Victoria. Salvinia molesta is a noxious weed in Victoria, and it is an offence to buy, sell, display or transport this plant. Salvinia species (such as Salvinia molesta, Salvinia minima and Salvinia natans) can appear very similar to each other, and it is only possible to distinguish between salvinia species through DNA testing. Throughout Australia, salvinia plants are advertised for sale on online platforms such as Facebook Marketplace, Gumtree and eBay. Recently we have seen a surge in advertisements listing plants as Salvinia minima (Sal minima, water spangles), despite this species not being present in Australia. To date, twenty-one salvinia specimens advertised for sale as Salvinia minima have been DNA barcoded by Agriculture Victoria. In all cases, results of these tests confirm the plants are, in fact, Salvinia molesta. It is highly likely that all salvinia plants present in Victoria are Salvinia molesta, despite any alternative labelling. Agriculture Victoria is also concerned as to whether any other species of salvinia are present in Victoria, due to the damaging and weedy nature of species within the salvinia genus and this can only be confirmed through DNA testing.

Page last updated: 13 Dec 2022