Common Name:

General Information

Trapa natans quadrispinosa is an annual aquatic herb with a rosette of floating leaves and submerged, paired but not opposite, pinnatisect and leaf-like adventitious roots[]. The plant can be free-floating in the water, or rooting in the mud in shallow water. It is also able to grow out of water in very wet, muddy soils[].
Often called water chestnut (though this name properly refers to a quite different plant, Eleocharis dulcis). The plant has a long history of use, with evidence showing that the seeds were a major component of the human diet several thousand years ago, Its use as a food crop has greatly declined in recent times in Europe, but it is a very important crop in many parts of Asia, especially China and India where it is widely cultivated for its nutritious, edible seeds and has various medicinal properties[, ]. The plant is also grown as an ornamental in aquaria and outdoor ponds.

Known Hazards

None known

Botanical References

Range

E. Asia - northern India, Nepal, Thailand, eastern and southeastern China, Japan, Russian Far East

Habitat

Stagnant or sluggish fresh water[].

Properties

Height	0.00 m
Cultivation Status	Cultivated, Ornamental, Wild

Cultivation Details

Trapa natans quadrispinosa is found mainly in the temperate zone s of the Himalayas, southeast China, Japan and the Russian Far East, also growing in Thailand. It grows best in areas where annual daytime temperatures are within the range 15 - 25°c, but can tolerate 10 - 35°c[]. When dormant, the plant (in the form of a seed) can survive temperatures down to about -25°c, but young growth can be severely damaged at 0°c[].
A water plant, usually growing in water up to 60cm deep, but recorded to tolerate depths from 30 - 360cm[]. It requires a sunny position in slightly acidic water[]. Dislikes calcium rich water[]. Prefers a rich soil[, , ]. Prefers a pH in the range 5.5 - 7.5, tolerating 5 - 8.2[].
In India, the fruit is broadcast in 30 - 69 cm deep nursery ponds and pressed into the mud, transplanted at the 4 - 5 leaf stage and replanted when 4 - 5 months old. Lateral pruning is carried out to accelerate flowering and fruiting[]. In China, the water chestnut is cultivated in running water[].
The plant is known to fix nitrogen from the water[].

Edible Uses

Seed - raw, cooked or dried and ground into a powder[, , , , , , , ]. A sweet floury and agreeable flavour[], similar in taste to sweet chestnuts (Castanea spp)[]. The seed contains up to 50% starch according to one report[], 16% starch, 3% protein in another report[] and 15% protein, 7.5% fat in a third[]. (Are all these reports talking about the same thing?). One report says that the raw nut contains toxins that are destroyed by cooking the seed[].

Medicinal

The fruit (seed) is used in Ayurvedic medicine as an antidiarrhoeal, aphrodisiac, appetizer, astringent, diuretic, nutrient, refrigerant and tonic. It is also useful in the treatment of lumbago, sore throat, bronchitis, bilious affections, fatigue and inflammation[, , ].
The fruits are used in the preparation of liniments to treat elephantiasis, pestilent fevers, rheumatism, sores, sunburn and skin complaints[, , ].

The juice of the stems is used to treat eye disorders[].

The plant is used medicinally to treat rabies, poisonous animal bites, diarrhoea, amoebic dysentery and other complications[]. It has allso been used in a herbal mixture that has proven to provide relief from the symptoms associated with recurrent herpes genitalis and labialis[].

The flowers are astringent in fluxes[].

The rind of the fruit has been discovered to have antibacterial activity, and is primarily effective against gram negative bacteria[]. A methanol extract of the fruit rind has shown a hypoglycaemic and antidiabetic activity, reducing and normalizing blood glucose levels[].

Agroforestry Uses:

The plant is known to fix nitrogen and phosphorus from the water[]. It has the potential to be used as a tool to reduce eutrophication, however, the vegetation must be removed annually prior to its decay in order to prevent the subsequent release of these sequestered nutrients back into the water[].
The plant may also be used in environmental reclamation projects, as it is capable of accumulating heavy metals, although not at levels as high as some other species commonly used in this capacity[].

Other Uses

The seeds are sometimes used as beads in necklaces and rosaries[, ].

The plant is a potential source of biomass. It has been recommended for use as paper pulp, fertilizer, compost and biofuel[].

Propagation

Seed - harvest in late summer and store overwinter in a jar of water in a cold but frost-free place. The seed can remain viable for up to 10 years at the bottom of a pond, but quickly loses its vitality if it is allowed to become dry. Sow in spring, placing one seed in each pot and submerging them under a few centimetres of water.