Water soldier is a water weed that can grow above the water in summer but is submerged for the rest of the year. It can overrun waterways, displacing other plants and animals.
Water soldier forms dense stands in waterways. It:
Water soldier is a perennial plant that can grow in water up to 5 m deep. For most of the year it grows under water. In spring the new leaves contain air pockets which help the plant float. In summer the plant flowers above the water. As older leaves die back in autumn they become waterlogged which causes the plant to sink again.
Water soldier can remain submerged all year round if there is not enough sunlight reaching the underwater plants.
Leaves above water are:
Underwater leaves are:
The flowers smell foul. Female and male flowers are usually on separate plants.
Female flowers:
Male flowers:
Water soldier does not currently grow in Australia. If it was introduced to NSW, it could invade freshwater ponds, lakes and streams.
It is native to Europe and central Asia.
Water soldier grows in temperate regions. Plants can grow in still or slow-moving fresh water up to 5 m deep but do not grow in water if the levels fluctuate. It tolerates water with a wide variety of pH values.
Seeds are released from the fruit in a pulp that sinks to the bottom. The seeds eventually float downstream. Seed production can be limited when male and female plants are not growing close to each other.
In summer, stolons produced from the base of the parent plant break away to form new rosettes. Up to 10 plants can form around each parent plant.
Cook, C. D., & Urmi-König, K. (1983). A revision of the genus Stratiotes (Hydrocharitaceae). Aquatic botany, 16(3), 213-249.
Efremov, A. N., Sviridenko, B. F., Toma, C., Mesterházy, A., & Murashko, Y. A. (2019). Ecology of Stratiotes aloides L.(Hydrocharitaceae) in Eurasia. Flora, 253, 116-126.
Government of South Australian (2014). Declared Plant Policy under the Natural Resources Management Act 2004 water soldier (Stratiotes aloides). Retrieved 30 July 2020 from: https://pir.sa.gov.au/__data/assets/pdf_file/0016/137320/water_soldier_policy.pdf
Harpenslager, S. F., Smolders, A. J., Kieskamp, A. A., Roelofs, J. G., & Lamers, L. P. (2015). To float or not to float: how interactions between light and dissolved inorganic carbon species determine the buoyancy of Stratiotes aloides. PLoS One, 10(4), e0124026.
Mulderij, G., Mooij, W. M., Smolders, A. J. P., & Van Donk, E. (2005). Allelopathic inhibition of phytoplankton by exudates from Stratiotes aloides. Aquatic Botany, 82(4), 284-296.
Sainty, G. R., & Jacobs, S. W. (2003). Waterplants in Australia (No. Ed. 4). Sainty and Associates Pty Ltd.
Snyder, E., Francis, A., & Darbyshire, S. J. (2016). Biology of invasive alien plants in Canada. 13. Stratiotes aloides L. Canadian Journal of Plant Science, 96(2), 225-242.
Please do not attempt to treat or dispose of this weed yourself. Report this plant if you see it anywhere in NSW by calling the helpline listed at the top of this page immediately.
NSW DPI will lead an initial response for the treatment and disposal of the plant to stop it from spreading.
See Using herbicides for more information.
PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L
(Only products registered for aquatic use)
Rate: One part product to 50 parts water
Comments: Spot spray
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate
PERMIT 9907 Expires 31/03/2025
Glyphosate 360 g/L
(Only products registered for aquatic use)
Rate: One part product to 9 parts water
Comments: Splatter gun
Withholding period: Nil.
Herbicide group: M, Inhibitors of EPSP synthase
Resistance risk: Moderate
The content provided here is for information purposes only and is taken from the Biosecurity Act 2015 and its subordinate legislation, and the Regional Strategic Weed Management Plans (published by each Local Land Services region in NSW). It describes the state and regional priorities for weeds in New South Wales, Australia.
Area | Duty |
---|---|
All of NSW | General Biosecurity Duty All pest plants are regulated with a general biosecurity duty to prevent, eliminate or minimise any biosecurity risk they may pose. Any person who deals with any plant, who knows (or ought to know) of any biosecurity risk, has a duty to ensure the risk is prevented, eliminated or minimised, so far as is reasonably practicable. |
All of NSW |
Prohibited Matter
A person who deals with prohibited matter or a carrier of prohibited matter is guilty of an offence. A person who becomes aware of or suspects the presence of prohibited matter must immediately notify the Department of Primary Industries |
Reviewed 2020