Free-Floating Aquatic Weed Identification

Definition: Free-Floating Aquatic Weeds have roots that are not attached to substrate and float on the water's surface. The most common Australian Free-Floating Aquatic Weeds are: Duckweed, Azolla, Liverwort, Salvinia, Water Lettuce and Water Soldier.

There are also 3 other types of Aquatic Weeds:

Duckweed

Species: Duckweeds Family: Lemnaceae

Distribution

NSW, QLD, VIC, SA, NT, ACT, WA, TAS

Description

This tiny floating aquatic plant with distinctive fern type leafed appearance grows in size from 1cm to 3cm in diameter, with roots trailing down on the bottom side of the plant up to 4cm long.

Life Cycle

Perennial

Origin

Native

Options

Ferny Azolla

Species: Azolla Filiculoides/Pinnata Family: Azollaceae

Distribution

NSW, QLD, VIC, SA, NT, ACT, WA, TAS

Description

From 1-2.5cm in diameter. Older plants in full sunlight are reddish, whereas plants in shade are greenish.

Life Cycle

Perennial

Origin

Native

Options

Liverwort

Species: Ricciocarpus Natans Family: Ricciaceae

Distribution

QLD, NSW, VIC, TAS

Description

Green with blackish outer edges. Appearance of leaf growing side-by-side or divided into two. Underside leaf bears purplish scales. Often found floating with Duckweeds on still water.

Life Cycle

Perennial/Annual

Origin

Native

Options

Salvinia

Species: Salvinia Molesta Family: Salviniaceae

Distribution

TAS, VIC, ACT, NSW, QLD, NT, SA, WA,

Description

Has floating leaves covered with tiny hairs which makes the weed waterproof. Has been known to double it's size extremely quickly in as little as 5-10 days. Prefers to grow in slow moving water bodies, Can spread through water fowl. Is a threat to biodiversity, including fish, insects or any plants underneath it's mat.

Life Cycle

Perennial

Origin

Introduced

Options

Water Lettuce

Species: Pistia Stratiotes Family: Araceae

Distribution

NSW, QLD, VIC, SA, NT, ACT, WA, TAS

Description

Also known as water cabbage. It can completely cover water bodies, reducing oxygen, killing fish & attracting mosquito's. Can be 10cm tall and 30 cm wide. Reproduces rapidly by offshoots. Occurs in slow moving waterways in tropical and subtropical warmer temperate regions.