Sagittaria

Scientific name: Sagittaria platyphylla
Declaration status: Class A and Class C.

Sagittaria is a Weed of National Significance.

For more information go to the Weeds of National Significance website.

Sagittaria is native to North America and was introduced to many continents as an ornamental plant.

It is not known how or why sagittaria was first imported into Australia.

It was first discovered naturalised near Brisbane in 1959, then in 1962 in Victoria and in 1964 in New South Wales.

It now occurs along the East Coast of Australia as far north as Cairns.

It is common in northern Victoria, south-eastern New South Wales and south-eastern Queensland.

It has been found in isolated locations around Adelaide, South Australia, and at Perth and Albany in Western Australia.

Sagittaria is not known to occur in the Northern Territory.

Watch the sagittaria video on youtube.

Impact

Sagittaria is an important weed of rice crops and wetlands in the Eastern States.

It is a threat to waterways and wetlands across Western Australia, especially to the Ord River Irrigation Area.

It is becoming a problem in irrigation channels, drains, creeks and wetlands, where it forms dense patches which obstruct water flow.

Sagittaria can have the following impacts:

  • dense infestations can reduce water flow
  • blocked irrigation channels can increase production costs
  • blocks natural waterways and chokes out native vegetation
  • may restrict access for recreational fishing, boating and swimming.

Identification

You should use this as a guide. There may be other plants or weeds that look similar.

  • aquatic plant rooted in the ground can grow submerged or emerging above the water surface up to 1.2m tall
  • stems are triangular-shaped in cross-section
  • submerged leaves are translucent and strap-like up to 50cm long
  • emergent leaves are lance-shaped up to 28cm long and 10cm wide and are on a long stalk
  • white or sometimes pink flowers appear at the top of a leafless stalk
  • flowers are always below leaf height in 2 to 12 whorls of three flowers arising from the same position on the stem
  • male flowers are at the top and female ones at the bottom, both male and female flowers have three petals
  • fruit is a cluster of one-seeded segments, each segment flattened, winged and 1.5mm to 3mm long.

Sagittaria weedSagittaria stems and branchesSagittaria stemsSagittaria leavesSagittaria leavesSagittaria flowersSagittaria fruit and seeds © User:Show Ryu / Wikimedia Commons / CC-BY-SA-3.0Sagittaria fruit and seed

For more information get the sagittaria identification fact sheet (505.5 kb).

If you are unsure, contact the Weed Management Branch.

Similar looking plants

There are several aquatic and semi-aquatic plants that look similar to sagittaria. If you think you have seen a plant that may be sagittaria, or if you have any doubt about the identification of the plant, contact the Weed Management Branch.

In particular, the plant species Echinodorus looks similar to sagittaria. There are several varieties of Echinodorus - including Echinodorus subalatus and E. longiscapus - growing and being sold in the Darwin region. They look similar to sagittaria but are not considered weeds.

Control

If you think you may have seen sagittaria, or have this weed on your property, do not attempt to control it.

Contact the Weed Management Branch immediately for assistance.

Sagittaria is on the alert list for environmental weeds. This is a list of weeds that threaten biodiversity and cause other environmental damage.

Spread

Sagittaria is a prolific seed producer. Seeds are tiny and can be spread by water or by attaching to water birds.

Spread prevention

If you have sagittaria on your property, and especially if it is flowering or seeding, contact the Weed Management Branch immediately for urgent help.

Last updated: 12 May 2018

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