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Water Soldier

Stratiotes aloides

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Plant Profile

Flowering Months:
Hydrocharitaceae (Naiad)
Life Cycle:
Maximum Size:
50 centimetres tall
Ditches, ponds, water.

White, 3 petals
Pinkish-white, 3-petalled flowers. Male flowers exist in small clusters of 1 to 3. Female flowers are solitary. Up to 4cm in diameter.
The fruit is a capsule.
An aquatic water plant, usually submerged. Dark greenish-brown, sword-shaped leaves. The margins of the leaves are spiny-toothed. Perennial.
Other Names:
Crab's Claw, Freshwater Soldier, Knight's Pondwort, Knight's Wort, Knight's Woundwort, Soldier's Yarrow, Wading Pondweed, Water Aloe, Water Houseleek, Water Pineapple, Water Sengreen, Water Soldiers.
Frequency (UK):
Occasionally seen  

Other Information


Stratiotes aloides, commonly known as water soldier or water aloe, is a species of aquatic plant in the family Alismataceae. It is native to Europe and Asia, and can be found in slow-moving or still freshwater, such as ponds, lakes, and ditches. It has long, narrow, spiky leaves that are arranged in a rosette and rise above the water surface. The leaves are typically green, but can turn red in low light conditions. The plant reproduces through small, inconspicuous flowers that appear on spikes above the water surface, and also through vegetative reproduction, by which small rosettes form on the tips of the leaves which will detach and become new plants. It is considered an invasive species in some parts of the world.


Water Soldier (Stratiotes aloides) is a unique aquatic plant that is native to Europe, Asia, and North Africa. Also known as water aloe, it is a member of the family Hydrocharitaceae and is often mistaken for a succulent due to its spiky, aloe-like appearance.

Appearance and Habitat

Water Soldier is a perennial plant that grows up to 30 cm long and has a rosette of stiff, green leaves that grow in a circular pattern. Each leaf is covered in sharp spines, which protect the plant from herbivores and make it difficult to handle. The leaves are buoyant, allowing the plant to float on the surface of the water, and they are covered in a wax-like coating that repels water.

Water Soldier prefers still or slow-moving freshwater, such as ponds and lakes, and is often found growing in shallow water up to 3 meters deep. It can also tolerate brackish water and is sometimes found in estuaries and coastal lagoons. The plant is a good indicator of the quality of the water in which it grows, as it is sensitive to pollution and will not survive in water that is heavily contaminated.

Ecological Importance

Water Soldier is an important plant in freshwater ecosystems, as it provides habitat and food for a variety of aquatic animals. Its floating leaves provide shade and shelter for fish, frogs, and other aquatic creatures, while its submerged roots provide a substrate for other aquatic plants to grow on.

The plant is also an important food source for waterfowl, such as ducks and swans, which eat the leaves and use the plant as nesting material. In addition, the plant's ability to absorb nutrients from the water makes it an important component of nutrient cycling in freshwater ecosystems.

Conservation Status

Although Water Soldier is not currently listed as endangered, it is considered rare in many parts of its range, and its populations are declining due to habitat loss and water pollution. In some areas, the plant is also threatened by the introduction of non-native species, such as the invasive Zebra Mussel (Dreissena polymorpha), which can attach to and damage the plant's leaves.

In conclusion, Water Soldier is a fascinating and important aquatic plant that plays a crucial role in freshwater ecosystems. It is a valuable indicator of water quality, and its decline should be of concern to conservationists and environmentalists alike. By protecting the habitats in which it grows, we can help ensure the survival of this unique and important plant for future generations.


Water Soldier reproduces both sexually and asexually. It produces small white flowers that emerge from the center of the rosette, usually in June or July. The flowers are pollinated by insects, and the resulting seeds are dispersed by water currents or animals. The plant can also reproduce asexually by producing daughter rosettes, or "offsets", which break away from the parent plant and grow independently.


Water Soldier has a long history of medicinal use in traditional medicine. The plant contains several biologically active compounds, including saponins, flavonoids, and tannins, which are believed to have a variety of therapeutic effects. It has been used to treat skin conditions, respiratory infections, and digestive problems, among other ailments.

In addition to its medicinal properties, Water Soldier is also valued as an ornamental plant for its unique appearance. It is sometimes cultivated in garden ponds or water features, although it can be difficult to grow outside of its natural habitat.


Water Soldier is threatened by a number of factors, including habitat loss, water pollution, and the introduction of non-native species. Human activities such as agriculture, urbanization, and industrialization can lead to the degradation of freshwater habitats, making them unsuitable for the plant to grow in. In addition, invasive species can outcompete Water Soldier for resources or damage its leaves, reducing its ability to survive and reproduce.

Conservation Efforts

Efforts to conserve Water Soldier have focused on protecting its habitat and controlling the spread of invasive species. In some areas, the plant has been designated as a protected species, and conservationists are working to restore degraded habitats and reduce pollution levels in waterways.

In addition, there are ongoing efforts to study the plant's biology and ecology, in order to better understand its role in freshwater ecosystems and develop effective conservation strategies. By working to protect this unique and valuable plant, we can help ensure the health and vitality of our freshwater environments.

Additional Facts about Water Soldier

Here are some additional interesting facts about Water Soldier:

  • Water Soldier is a popular plant in the aquarium trade due to its unique appearance and ease of care. However, it can be difficult to maintain in an aquarium because it requires a large amount of space and can produce a lot of organic matter, which can lead to poor water quality.

  • In some parts of Europe, Water Soldier was traditionally used as a substitute for soap. The plant contains saponins, which can create a lather when agitated in water, making it useful for washing clothes or cleaning surfaces.

  • Water Soldier is sometimes called "horned water starwort" or "water pineapple" due to its spiky appearance.

  • The spines on Water Soldier's leaves are actually modified leaves called stipules, which are a type of appendage that grows at the base of the leaf. Stipules are found on many plant species and can take on a variety of shapes and functions.

  • Water Soldier is sometimes confused with another aquatic plant called Water Chestnut (Trapa natans), which also has spiky leaves and grows on the surface of the water. However, Water Chestnut is a completely different plant species, and is considered invasive in many areas where it has been introduced.

Distribution Map

Reproduced by kind permission of the BSBI.

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