Common Name: Water Lettuce

General Information

Pistia stratiotes is a small, evergreen perennial plant with feathery roots[]. Free-floating in lakes, ponds etc, the plant forms rosettes of leaves up to 10cm wide and 6cm tall with a flowering stem up to 12cm tall[]. The plant can spread quickly, especially in still water, to form quite extensive clumps.
The plant is sometimes used locally for food, but only usually where nothing better is available. It has a range of medicinal applications and is also used as a source of organic matter and to remove toxins from polluted water. It is sometimes grown as an ornamental in the tropics and as an indoor aquatic ornamental in temperate regions.

Known Hazards

All parts of the plant contain calcium oxalate crystals plus unknown toxins[]. Ingestion, in large quantities, can cause an intense burning and swelling of the lips, tongue, and throat; nausea and vomiting. Diarrhoea may also occur[].

Botanical References

,

Range

Tropical and subtropical areas of Africa; Asia to New Guinea and N. Australia; southern N. America, S. America, the Caribbean and Central America.

Habitat

Water fields, lakes, ponds[]. Found in a wide range of aquatic habitats at elevations from sea level to over 1,000 metres[].

Properties

Weed Potential	Yes
Edibility Rating
Medicinal Rating
Other Uses Rating
Habit	Evergreen Perennial
Height	0.10 m
Growth Rate	Fast
Pollinators	Insects
Cultivation Status	Ornamental, Wild

Cultivation Details

Found though much of the tropics and subtropics at elevations from sea level to more than 1,000 metres. The optimal growth temperature range for the plant is 22 - 30°c[]. Plants cannot tolerate frosts[].
A free-floating, aquatic plant, succeeding in full sun or partial shade[, ]. Requires a lime-free water with a pH preferably in the range 6.5 - 7[]. Plants can survive in a dwarf form if stranded in wet soil[].
Plants can spread rapidly in warm climates, where they can become invasive[]. They are considered to be noxious weeds in many areas[]. Like Water hyacinth (Eichhornia crassipes), this plant also blocks irrigation canals; provides a breeding ground for mosquitoes; and chokes fishery waters[].
The plant provides a useful cover for spawning fish[].

Edible Uses

Leaves - cooked[]. The leaves are sometimes added to soups, but they need to be parboiled first in order to remove the acrid calcium oxalate crystals[]. The young leaves have been cooked and eaten, but their taste is first nondescript and then sharp because of the calcium oxalate crystals[].
The plant has been used as a famine food, but people do not generally find it very palatable[].

The ashes of the burnt plants can be used as a salt substitute[].

Medicinal

The plant is used to treat swellings and urinary tract infections[].

The leaves are diuretic, emollient, expectorant, laxative and stomachic[]. They are used in the treatment of dysuria and stomach problems[]. They are mixed with rice and coconut milk in the treatment of dysentery; and mixed with rose water and sugar for treating coughs and asthma[]. The leaves are used in the treatment of gonorrhoea, probably because they act as a diuretic[].
The leaves are used externally to treat skin diseases, such as boils, piles and syphilitic sores[]. They are also applied to haemorrhoids[]. A decoction is added to bathwater to treat oedema[].

The roots are used externally to treat burns. They are pounded and applied as a poultice[].

Some caution should be exercised in the use of this plant, an overdose may cause acute diarrhoea[].

Agroforestry Uses:

The plant is used as a manure, especially for its high potash content[].
Experiments have shown that the plant is a good waste water-cleaning agent, as it takes up nitrogen and phosphorous compounds, as well as heavy metals, and harbours active microbial organisms[].

Other Uses

The plant can be used with soap for taking stains out of clothing, probably because of its potash content[].

The leaves have insecticidal properties[].

Propagation

Seed - it needs to be kept moist. In nature, the seeds float in the water for a few days, after which they sink and germinate. The seedling appears at the surface in 5 days[].
Division of the new plants formed at the ends of stolons radiating out from the mother plant[].

Add a Comment:

If you have any useful information about this plant, please leave a comment. Comments have to be approved before they are shown here.

Name:

Email(Private):

Message:

Captcha: what is lesser, 17 or 71?