Water soldiers

Stratiotes aloides
Aquatic
Whorled
Simple
White
Green

Water soldier is mainly invisible as it grows under the water and attaches itself to the bed. During its flowering time the stem breaks off and rises to the surface, and the tips of the leaves and the inflorescence rise above the surface of the water. The smell of decomposing flesh that the flower emits attracts flies and perhaps some butterflies to pollinate it.

Common names 
Also known as: water pineapple, water aloe,
Family 
Hydrocharitaceae
Deciduous 
No
Flowering time 
summer
Native/Exotic 
Exotic
Origin 
Native to Europe
Notifiable 
Yes
State declaration 
Category 1
Council declaration 
As per State Declaration
Known distribution 

Not yet naturalised or cultivated in Australia.

Habitat 

Stratiotes aloides usually inhabits shallow stagnant waters, mainly eutrophic and mesotrophic, with substratum of mud and organic deposits. Stratiotes aloides can grow in depths of up to 6.5m. Stratiotes aloides is found mainly in sheltered bays of larger lakes, backwater ponds, ditches and canals. Stratiotes aloides is limited to freshwater. 

Habit 

Water soldier has an unusual growth habit. It is a submerged plant except in summer when it rises to the water surface to flower. The new leaves that grow in spring contain air pockets allowing the plant to float. As the older leaves die back in autumn they become waterlogged which causes the plant to sink again.

Water soldier can remain submerged all year round and can grow in depths of up to 5 m.

Potential to become serious pest if introduced and planted in aquariums or outdoor ponds.S. aloides can form dense mats of floating vegetation that crowds out native plant species. It can change water chemistry. The large dense mats and the serrated sharply pointed foliage of S. aloides can restrict recreational use of the water and pose a danger to swimmers and other people that handle the plant.

Stem and leaves 

Submerged leaves are thin, brittle and droop at an angle. Submerged leaves can grow up to 60 cm (or rarely 110 cm long) and up to 1 cm wide with somewhat weak spines. Emergent leaves are thick, rigid, brittle, and dark green and are usually less than 40 cm long and 1-4 cm wide, with well-developed spines along leaf margins. The emergent form develops rosettes at the surface of the water. The roots of S. aloides can be up to 180 cm long but are usually less.

Flowers and fruits 

The flowers have three white to pinkish petals. Fruits are fleshy berries that can each contain up to 24 seeds. It also spreads by offsets on the stolons.

Reproduction and dispersal 

Reproduces mainly by vegetative means, as mature plants produce plantlets which detach and are carried downstream to take root in other locations. Plants also produce seed encased in a berry-like fruit, so that when the plant submerges again the seeds float downstream, but is this method of spread is less common.