Weed Identification

Australia > > Glush Weed

Glush Weed

Hygrophila costata

Alternative Name(s): Yerba de hicotea, Hygrophila brasiliensis, Hygrophila guianensis, Ruellia costata

Family: Acanthaceae.

Form: Water plant

Origin: Native from southern Mexico to Argentina.

Flowers/Seedhead: White, about 10 mm long and with sepals joined below half way. Flowers all year round.

Description: Aquatic and semi-aquatic herb to 1.5 m high. Stems hairless to shortly hairy with nonglandular hairs. Leaves narrowly elliptic, 318 cm long, 14 cm wide tapering to the base, margin almost entire. Fruit 68 mm long, with about 20 seeds. Seeds pale brown, round, flattened, about 0.3 mm wide.

Distinguishing features: Distinguished by plants not spiny; stems 4-angled; leaves in opposite pairs; inflorescences of 10 or more flowers in axillary whorls; flowers surrounded at base by sepals 5.56 mm long, petals joined in a2-lipped tube, upper lip shortly 2-lobed and hooded, lower lip 3-lobed, shortly hairy outside but without hairs inside; stamens 4, 2 long and 2 short, joined at the base, all fertile and projecting past the petals; capsule spindle-shaped.

Dispersal: Spread by seed and locally by rooting at nodes.

Confused With: Lycopus australis, Australian Water Horehound, a native species that has leaves with coarsely toothed margins.


Leaves & whorls of flowers,
Lake MacDonald, Qld, March

Notes: Sold as an aquarium plant. Now a significant water weed in northern coastal New South Wales and south eastern Queensland where it displaces most other species in shallow water and neighbouring damp soil.

References:

    Waterplants in Australia. G. Sainty and S. Jacobs, 4th edition, 2003, pages 232233.

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


Root system

White flowers,
Casino, NSW, Jan
photo J.R.Hosking

Infestation on margins of Lake MacDonald, Qld, March

This weed has been included in the WEEDeck field guide as card W20.
More information about WEEDeck is available from Sainty & Associates Pty. Ltd.

It has also been included in the 'Jumping the Garden Fence' report (WWF-Australia PDF - 1.19mb) which examines the impact of invasive garden plants on Australian agricultural land and natural ecosystems.

 

Australia > > Glush Weed

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