Submerged Aquatic Weed Identification

Definition: Submerged aquatic plants grow below the water's surface, whether attached to substrate or not. Some submerged aquatic plants may spend part of their life cycle above the water’s surface.

There are also 3 other types of Aquatic Weeds:

Ribbonweed

Species: Vallisneria nana        Family: Hydrocharitaceae 

Distribution
NSW, QLD, NT, WA,

Description
Forms slender trailing stems that root at the base. The leaves are long and strap-like, with narrow translucent sheaths at the base. The blades are also long and narrow with parallel margins, or gradually widening above, erect, but with the top end floating on the surface of the water (between 15-100cm long or longer, 1-3cm broad). The tips are rounded and minutely serrate, green and membranous, often covered with brown slime and silt.

Life Cycle
Perennial

Origin
Native

Mechanical Control

Sea Tassel

Species: Ruppia megacarpa        Family: Potamogetonaceae  

Distribution
NSW, SA, VIC, WA

Description
Found in hypersaline lakes, estuaries and lagoons and coastal areas of cooler climate. Produces leaves on stems up to 2m long. Leaves alternate in zig-zag arrangement. Immature flowers and fruit on coiled stalk.

Life Cycle
Perennial

Origin
Native

Mechanical Control

Giant Arrowhead

Species: Sagittaria montevidensis    Family: Alismataceae

Distribution
NSW

Description
oval/linear shaped leaf blades with pointed tips (arrows), up to 25cm long and 10 cm wide at the top of each stem (leaf stalk). It also has long narrow strap-like submerged leaves up to 50cm long. Flowers appear in whorls or coils and grow on leafless stems. Male flowers are 3cm across with three white petals and yellow centres. Female flowers have no petals, resembling flattened green berries. Flowers appear below the height of the leaves during spring and autumn. 

Life Cycle
Perennial/Annual

Origin
Introduced

Mechanical Control

Blunt Pondweed

Species: Potamogeton ochreatus    Family: Potamogetonaceae

Distribution
NSW, QLD, SA, TAS, VIC, WA

Description
Submerged annual or perennial with cylindrical stems up to 4m long, with stalk less translucent, narrow flat linear leaves up to 10cm long with rounded tips. Inflorescence an emergent, dense spike to 3cm long.

Life Cycle
Perennial/Annual

Origin
Native

Mechanical Control

 

Hornwort

Species: Ceratophyllum demersum    Family: Ceratophyllaceae 

Distribution
NSW, NT, QLD, SA, VIC, WA

Description
It produces leaves and forms a shoot about 80mm long. This breaks off and floats to the surface where it grows floating freely in the water. Stems up to 2m long, leaves whorled, forked 2-4 times.

Life Cycle
Perennial

Origin
Native

Mechanical Control

Water Plantain

Species: Alisma plantago-aquatica    Family: Alismataceae

Distribution
NSW, VIC

Description
It is a hairless plant that grows in shallow water, consists of a fibrous root, several basal long stemmed leaves 15-30cm long, and a triangular stem up to 1m tall. It has branched inflorescence bearing numerous small flowers, 1cm across, with three round or slightly jagged, white or pale purple, petals

Life Cycle
Perennial

Origin
Native

Mechanical Control

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