Scientific name: Eichhornia crassipes (Mart.) Solms-Laub

Synonyms: Pontederia crassipes Mart; Eichhornia speciosa Kunth

Common name:Water hyacinth

Family: Pontederiaceae

Origin:

Native of tropical America.

Habit:

Aquatic plant forms dense clumps on the surface of the water, spongy petioles provide bouyancy.

Habitat:

Serious pest of waterways where water is still or slow moving, especially when there are high levels of available nutrients.

General description:

Stems and leaves

Stems are creeping, forming runners. Roots are feather-like 2-100 cm long. Plants may have two different types of leaf stalks (petioles) either inflated and spongy 3 cm long or, when the stem becomes congested with leaves, new leaves are long and slender up to 30 cm long. Leaf blades range from elliptical to ovate to round and are of varying size, 2-10 x 2-9 cm. Leaves are glossy and hairless, with semi-parallel veins following the outline of the leaves.

Flowers and fruit

Flowers are showy, zygomorphic, with sepals and petals forming a tube 1-2 cm long with 6 purple lobes 2-4 cm long, the upper lobe with a yellow spot surrounded by blue. Flowers are arranged on an upright spike up to 15 cm long. Fruits are capsules, 1-1.5 cm long, with three compartments containing up to 300 seeds. Seeds are ovoid and ribbed 1.0-1.5 mm long.

Distinguishing characteristics:

A floating plant with showy purple or lilac flowers and leaves with inflated stalks.

Noxious status:

This species is declared a noxious weed in all states and territories of Australia.

Sources:

Kleinschmidt, H.E., Holland, A. and Simpson, P. (1996). Suburban Weeds. 3rd Edition. Department of Primary Industries, Brisbane.

Parsons, W.T. and Cuthbertson, E.G. (1992). Noxious Weeds of Australia. Inkata Press, Melbourne.

Stanley, T.E. and Ross, E.M. (1983-1989). Flora of South-eastern Queensland. Volume 3. Department of Primary Industries, Brisbane.