Australia > All Weeds > Water Hyacinth

Water Hyacinth

Eichhornia crassipes

Origin: Native of tropical South America.

Africa

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Flower by Tim Waters

Family: Pontederiaceae.

Known Hazards: Eating the plant, which is reported to contain HCN, alkaloid, and triterpenoid, may induce itching. Fresh plants contain prickly crystals. Plants sprayed with 2,4-D may accumulate lethal doses of nitrates.

Habitat: Water courses. Moist and boggy areas at elevations of 200 - 1500 metres in Nepal.

Edibility Rating: 2 (1-5)

Medicinal Rating: 0 (1-5)

Physical Characteristics: Free-floating perennial to 65 cm tall. Leaves basal, young plants with leaf stalks to 25 cm long and inflated at the base and older plants with leaf stalks to 60 cm long and without inflated bases. Roots feathery, black to purple, to 1 m long; usually short if water nutrient rich. Seed ovate–oblong, ribbed, about 1 mm long.
Flowers: In clusters on stems mostly taller than leaves. Flowers to 7 cm wide, lasting for 1 to 2 days and when all flowers on the spike have matured the spike turns down into the water. The flowers are hermaphrodite (has both male and female organs)It can fix Nitrogen.

Distinguishing features: Distinguished by pale blue–lavender flowers with darker purple and yellow blotch, and some leaves with a swollen, buoyant base of leaf stalk.

Dispersal: Seeds may germinate within days or may remain dormant for up to 15 or more years. Mainly increases in density by daughter plants produced on stolons.



Edible Uses

Young leaves and petioles - cooked. Virtually tasteless. Said to be used as a carotene-rich table vegetable in Formosa. Javanese sometimes cook and eat the green parts and inflorescence. Flower spikes - cooked.

Medicinal Uses

None known

Other Uses

Biomass; Pollution. Water hyacinths are potentially an excellent source of biomass. Through an anaerobic fermentation process, polluted hyacinths can be converted to the natural gas methane - a costly process that may become more economical as supplies of underground natural gas are depleted. Dried and cleansed plants can be used as fertilizer and plant mulch. Eventually, living aquatic plants might serve aboard long-distance manned spacecraft, absorbing wastes and converting carbon dioxide to oxygen, then being themselves converted into food. The plant can be cultivated for use in wastewater treatment, and can be incorporated into a system where the biomass is harvested for fuel production. Since this biomass is a by-product of wastewater treatment, it has a positive environmental impact, and thus poses no threat as competitor to food, feed, or fibre-producing plants. Wilted water hyacinth, mixed with earth, cow dung, and woodashes in the Chinese compost fashion, can yield useful compost in just two months. Although potential yields are incredible, so are the costs of removal or attempted eradication of this water weed. Standing crops have been estimated to produce 100-120 tonnes per hectare per year. Under ideal conditions, each plant can produce 248 offspring in 90 days. Water hyacinth roots naturally absorb pollutants, including such toxic chemicals as lead, mercury, and strontium 90 (as well as some organic compounds believed to be carcinogenic) in concentrations 10,000 times that in the surrounding water. In Africa, fresh plants are used as cushions in canoes and to plug holes in charcoal sacks.

Notes: Attractive but troublesome plant that has spread worldwide, obstructing waterways, reducing fish production, harbouring mosquitoes, and severely disrupting life in some communities along rivers and lakes, mostly between latitudes 35° north and south of the equator. Luxuriant growth is usually a symptom of nutrient enrichment (eutrophication). Water Hyacinth will not thrive in good quality tap water. Biological control has been effective in some regions, particularly in tropical areas.
References:





Infestation at Eastern Creek, Sydney. Image by Tony


Philippines, image by IRRI

 

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