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Water lettuce

Pistia stratiotes
Landscape: , | Plant Form:
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Water lettuce is a perennial stoloniferous aquatic herb to 20 cm above water level with feathery roots.

Leaves are wedge-shaped, pale green, buoyant towards base, to 15 cm long and to 8 cm wide.

Flowers are small and partly concealed at the base of the plant. Flowers occur on a column surrounded by a whitish slit funnel-shaped bract (spathe).

A large number of unbranched feathery roots up to 80 cm long are submersed in water beneath the leaves of the plant.

Water lettuce is dispersed by seed and vegetatively by daughter plants at the end of stolons. Seeds, seedlings and mature plants are moved by water and wind.

Water lettuce grows best on still or slow moving bodies of fresh water such as farm dams, reservoirs, lakes, rivers and creeks.  It will tolerate temperatures between 15°C and 35°C; however optimum temperatures for growth range between 22°C and 30°C.

Water lettuce is frost sensitive and growth is limited in temperate zones by long cool winters.

It can survive for long periods on mud banks or in other damp locations such as roadside culverts.

 

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