Weed Identification

Australia > > Water Hyacinth

Water Hyacinth

Eichhornia crassipes

Family: Pontederiaceae.

Form: Water plant

Origin: Native of tropical South America.

Flowers/Seedhead: 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.

Description: 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.

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.


Showy flowers & curved, nearly round
leaves

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:

    Noxious Weeds of Australia. W. Parsons and E. Cuthbertson, 1992; pages 139–144. Biology of Australian Weeds. R. Groves et al. Vol. 1, 1995, pages 111–121.

Web References: Search Australian web sites for further information on this weed.

Germinating seeds
compared with a pin
photo R. Brayne
Gingham Watercourse, Moree, NSW, 1975
Daughter plants produced
on stolons

This weed has been included in the WEEDeck field guide as card W05

More information about WEEDeck is available from Sainty & Associates Pty. Ltd.

 

Australia > > Water Hyacinth

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