Water Soldier (Stratiotes aloides)
French common name: Aloès d’eau

Water soldier resembles the aloe plant or the top of a pineapple.

The serrated edges on the stem are a key characteristic in identifying water soldier.

Order: Alismatales
Family: Hydrocharitaceae

Did you know? One of the only known water soldier populations in North America is in the Trent River in eastern Ontario.

Water soldier is a submerged, perennial aquatic plant that has long, thin, serrated leaves that grow in a rosette formation. When present, flowers rise above the plant and have three white/green sepals and three white petals. Male and female flowers occur on separate plants and look similar. Fruit is a barrel-shaped, berry-like capsule. Vegetative reproduction is believed to be the primary means of spread in North America, although sexual reproduction may be possible. The dense mats that form crowd out other vegetation and alter water chemistry, causing decreased biodiversity of native aquatic species. Water soldier can be submerged up to 5 m but floats to the surface in summer. This poses a threat to summer recreational activities such as fishing, boating, and swimming. Boat motors can break up plants allowing them to spread and invade new areas. Learn to identify water soldier and avoid spreading it by slowing down when boating through areas it is present and by cleaning recreational equipment after use. The only population in North America is in the Trent River (Ontario) and there are many efforts in place to control and prevent its spread.

Water soldier is similar in appearance to an aloe plant, spider plant, or the top of a pineapple. Water soldier can be mistaken for common native species such as bur-reed, arrowhead, or eelgrass.

The leaves of this plant are 40 cm long and shaped like thin swords with very sharp serrated edges. The leaves form a large circle and are bright green in colour. In Ontario water soldier rarely produces flowers. However, if present, the flowers are white with three petals. 

Currently the largest population of water soldier is located in the Trent River in Ontario. It is extremely important that the population stays isolated and does not spread. The Ministry of Natural Resources and Forestry, with support from the Ontario Federation of Anglers and Hunters, Lower Trent Conservation, Parks Canada, and the Ontario Ministry of the Environment, Conservation and Parks conduct monitoring and and input control measures to stop the spread of water soldier.

Map of invasive water soldier distribution in 2015 in the Lake Seymour area, Ontario (Canada), estimated by means of boat-based surveys (produced by the Ontario Ministry of Natural Resources and Forestry; © Queen’s Printer for Ontario 2015). Red zones, dense colonies; beige zones, scattered plants; yellow zones, single plants; black rectangle, study area where UAS aerial imagery was collected.

Water soldier has several negative impacts (Ontario, 2018): 

– Forms dense mats of floating vegetation

– Crowds out native vegetation resulting in decreased plant biodiversity

– Has the potential to alter surrounding water chemistry, which may harm phytoplankton and other aquatic organisms

– Dense floating mats can hinder recreational activities such as boating, angling, and swimming

– Sharp serrated leaf edges can cut swimmers and individuals who handle this plants. Caution should be taken whenever handling the plant.

You can help prevent the spread of water soldier by learning how to identify it and avoid accidentally spreading it with your watercraft.

– Avoid infested areas or reduce your speed when traveling by infestations. Boat wake can dislodge plants and offsets and allow them to spread to new areas.

– Inspect your boat, trailer, and equipment after each use. Remove all plants, animals, and mud before moving to a new waterbody.

– Avoid planting water soldier in your water garden or aquarium. Water gardeners should only use native or non-invasive plants and are encouraged to ask garden centers for plants that are not invasive.

In the province of Ontario, it is illegal to import, possess, deposit, release, transport, breed/grow, buy, sell, lease or trade water soldier under the Ontario Invasive Species Act.

Report sightings to the Invading Species Hotline 1-800-563-7711 or visit Invading Species. 






Fact Sheets


Water soldier Stratiotes aloides L.(Hydrocharitaceae) as a substratum for macroinvertebrates in a shallow eutrophic lake

M Tarkowska-Kukuryk – Polish Journal of Ecology, 2006 – infona.pl
The importance of water soldier (Stratiotes aloides L.) as a colonization substratum for
epiphytic and mining fauna has been investigated in the shallow, eutrophic lake in East
Poland. Samples were taken in May, July and October in 2000-2001. Studies focused on …

Carbon source of the water soldier, Stratiotes aloides L.

HBA Prins, MB De Guia – Aquatic botany, 1986 – Elsevier
Stratiotes aloides L. is one of the aquatic plants in The Netherlands which is being
threatened by anthropogenic manipulation of aquatic ecosystems. S. aloides normally grows
in water with a high content of dissolved inorganic carbon (DIC), moderate pH and high free …

Biodiversity of zooplankton (Rotifera and Crustacea) in water soldier (Stratiotes aloides) habitats

M Karpowicz, J Ejsmont-Karabin, M Strzałek – Biologia, 2016 – degruyter.com
The qualitative and quantitative structure of rotifer and crustacean zooplankton inhabiting
Stratiotes beds and pelagial zone have been studied in different types of lakes. In 12 lakes
we recorded 151 rotifer and 52 crustacean species, with more than 90% of them being …

[PDF] An investigation of the reproductive ecology of crab’s-claw in the Trent River, Ontario, Canada

Weissflog, N., and E. Sager. 2016.  An investigation of the reproductive ecology of water soldier in the Trent River, Ontario, Canada. Journal of Aquatic Plant Management 54: 72-77

Crab’s-claw (Stratiotes aloides L.) is an aquatic macrophyte native to northern Eurasia and often sold in North America in the aquarium and water garden plant trade. In 2008, the first wild crab’s-claw population in North America was discovered in the Trent-Severn Waterway in Ontario…

Current Initiatives

Further Reading

The Invasive Species Centre aims to connect stakeholders. The following information below link to resources that have been created by external organizations.