Salvinia

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Salvinia (Salvinia molesta) is a State prohibited weed.

Handful of salvinia

Why you must report salvinia

Salvinia is banned in Victoria and across Australia.

Brought here for its beauty as a plant for fish tanks and ponds, salvinia is now in rivers and lakes in Queensland, New South Wales, the Northern Territory, and Western Australia.

Salvinia likes to grow fast when the water is nutrient rich, and the temperature is between 20 and 30°C.

In just one season, it can cover a whole dam, making it important to get rid of it as soon as you see it, to stop it from establishing and spreading .

Salvinia is a plant that floats on water and can cover large areas. It can clog up rivers, stop water from going where it should, and mess up fun activities like swimming and fishing. Plus, it is bad for the plants and animals that live in the water.Salvinia originated in South America and is a problematic weed in:

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

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.

Salvinia has small, oval shaped leaves that grow in pairs and are covered in eggbeater shaped waxy hairs that repel water.

When crowded, leaves become tightly packed and deeply folded. Isolated plants have leaves that are oblong to oval or round, and lie flat on the water surface.

Submerged leaves look like roots, with short brown hairy stalks ending in hairy filaments that can grow up to 30 cm long.

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

n Victoria, we only have one kind of salvinia, and it is called Salvinia molesta. This plant is a big problem in Victoria, and it is against the law to buy, sell, show, or move this plant.

Some salvinia plants might look a lot like each other, Salvinia molesta looks a lot like other plants, such as Salvinia minima, and Salvinia natans. You cannot tell them apart just by looking at them. You need to use DNA tests to be sure.

People selling salvinia plants on websites like Facebook Marketplace, Gumtree, and eBay all over Australia. Lately, there have been many ads saying they are selling Salvinia minima (also called water spangles), even though this  species has not been found  in Australia.

Agriculture Victoria checked over 30 of these plants with DNA tests, and every time, they turned out to be Salvinia molesta. It is very likely that all the salvinia plants in Victoria are the same, even if they are advertised as something else.

Have you seen this weed?

Page last updated: 11 Dec 2023