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Water Soldier

Stratiotes aloides
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What is Ontario Doing?

To prevent the further spread and introduction of this unwanted invader in the province, Ontario has regulated water soldier as a prohibited invasive species under the Invasive Species Act, 2015. For more information on the Act, visit

The Ontario Ministry of Natural Resources and Forestry has developed a prevention and response plan to enable people and organizations to undertake low risk activities to monitor, control, and in some cases eradicate these invasive plants without the need for an authorization under the Invasive Species Act, 2015. The plan also includes detailed best management practices for water soldier.

To view the prevention and response plan for water soldier, follow this link: Water Soldier Prevention and Response Plan PDF


Water soldier is an invasive aquatic perennial plant that is native to Europe and Northwest Asia. The populations that occur in Ontario are within the Trent-Severn Waterway, the Black River (near Sutton, ON) and in Red Horse Lake north of Gananoque. Prior to being regulated as a prohibited invasive species under Ontario’s Invasive Species Act, water soldier was sold for use as an ornamental plant in water gardens, which is the most likely source of its introduction to the wild.

For an up to date distribution map of water soldier in Ontario, visit

Impacts of Water Soldier

  • Forms dense mats of floating vegetation, creating stagnant waters
  • Crowds out native vegetation resulting in decreased plant biodiversity.
  • Has the potential to alter surrounding water chemistry, which may harm phytoplankton and other important aquatic organisms.
  • Dense floating mats of water soldier can hinder recreational activities, such as boating, angling, and swimming.
  • Sharp serrated leaf edges can cut swimmers and individuals who handle water soldier plants. Caution should be taken if you come in contact with the plant.

Since water soldier has been listed as a prohibited species under the Invasive Species Act, 2015, it is important to prevent the plant’s further introduction and spread to new locations. To prevent further spread, an inter-agency working group consisting of the Ontario Federation of Anglers and Hunters, Parks Canada, the Ministry of Natural Resources and Forestry, Ministry of Environment, Conservation and Parks, Trent University, Lower Trent Conservation authority are monitoring and tracking the spread of water soldier within Ontario waterbodies and undertaking a variety of control measures to prevent its spread.

How to Identify Water Soldier

Identifying features and characteristics of this plant include the following:

  • It is a submerged aquatic plant, which becomes buoyant during the summer months. As the leaves mature, they become waterlogged and the plant sinks below the water’s surface.
  • Leaves can reach up to 40 cm (1.3 ft) long, are sword-shaped, bright green, with sharp spines, and form a large ‘rosette’ or group of leaves arranged in a circle.
  • Flowers, if present, are white with three petals. Flowering of water soldier is exceptionally rare in Ontario, so this should not be used as a main identification characteristic.
  • Roots can be lightly rooted, but are not always attached to the mud at the bottom.
  • Plants can be found growing in depths of up to 5 m (16 ft).
  • Mature water soldier plants produce offsets or clones, which are similar to those produced by the household spider plant.

Water soldier is similar in appearance to an aloe plant, household spider plant, or the top of a pineapple. Water soldier may be confused with other aquatic plants in Ontario, such as native bur-reeds, arrowheads, or eel-grass. However, none of these plants have serrated leaf edges, which can be used to easily distinguish water soldier from these other aquatic plants.

What You Can Do

  • Learn how to identify water soldier and how to prevent accidentally spreading this plant with your watercraft or fishing equipment. This is especially important if you are planning to do work or participate in recreational activities in infested areas of the Trent-Severn Waterway or other areas that contain water soldier.
  • Never buy or keep water soldier in your water garden or aquarium. It is against the law to import, possess, deposit, release, transport, breed/grow, buy, sell, lease, or trade water soldier in Ontario.
  • Avoid infested areas and reduce your speed when travelling near water soldier infestations. You must take all reasonable precautions to avoid spreading water soldier to new areas of a waterbody.
  • Clean, Drain, Dry your boat, trailer, and other equipment after each use.
  • Never deposit unwanted aquarium or water garden plants into Ontario’s lakes or rivers. Dispose of them in the garbage or away from any waterbody.
  • If you have any information about the illegal importation, distribution, or sale of water soldier, report it immediately to the MNRF at 1-877-847-7667, toll-free anytime. You can also call Crime Stoppers anonymously at 1-800-222-TIPS (8477).
  • If you find  water soldier or another invasive species in the wild, please contact the toll-free Invading Species Hotline at 1-800-563-7711, visit EDDMapS, or search for the ‘Invasive Species in Ontario’ project on to report a sighting.

Resource Files


OFAH/OMNRF Invading Species Awareness Program. (2021). Water Soldier. Retrieved from:
This factsheet may be reproduced for non-commercial purposes.

Header photo by Matt Smith, MNRF

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