Sagittaria

(Sagittaria platyphylla, syn. Sagittaria graminea)

Status of sagittaria in Tasmania

Sagittaria is a declared weed in Tasmania under the Tasmanian Biosecurity Act 2019 and associated Regulations. The importation, sale and distribution of sagittaria are prohibited in Tasmania.
The legal responsibilities of landholders and other stakeholders in dealing with sagittaria are laid out in the Sagittaria Weed Management Plan.

What does sagittaria look like?

Sagittaria is a perennial (long-lived), emergent aquatic herb that grows to around 1.2 metres high in shallow permanent water bodies. Unlike most other species of this genus (for example the weed arrowhead, S. montevidensis), the above-water leaves do not have basal lobes giving them an arrow-like shape. Instead the leaves are ovate in shape, 25 cm long and 8 cm wide. Sagittaria also produces submerged leaves that are strap-like and grow to 50 cm long.
The flowering stems are erect and bear whorls of three at the apex. The flowers are white and have three petals. Sagittaria has fibrous roots and fleshy rhizomes (underground stems). The leaves and flowering stems arise from the rhizomes.
Spread is via seed. Seed is spread in water, and in mud adhering to machinery, boots and animals. Sagittaria has also been spread as part of the ornamental plant trade.

Sagittaria platyphylla flowers & plants, © Hugh Wilson.

Impacts of sagittaria

Sagittaria is a serious weed of irrigation channels and drainage ditches.

Where does sagittaria occur

Sagittaria is a native of North America. On mainland Australia, sagittaria has naturalised in New South Wales, Victoria and South Australia.
Sagittaria has not naturalised in Tasmania.

What you need to do

If you locate sagittaria anywhere in Tasmania, or if you find a plant that you think could be sagittaria, immediately contact Biosecurity Tasmania on 03 6165 3777 to report this weed.

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