Native to Mexico and Argentina, hygrophila is a flowering, erect herb that grows on creekbanks and in shallow freshwater wetlands.

Hygrophila has now naturalised in New South Wales and is an emerging problem for Queensland's waterways. The main danger is that aggressive hygrophila growth will pose a competitive threat to native water plants.

You must manage the impacts of hygrophila on your land.

You must not give away, sell or release hygrophila into the environment.

Scientific name

Hygrophila costata

Other names

  • Gulf swamp weed, glush weed


  • Erect, emergent herb up to about 1m tall.
  • Leaves opposite, simple, 3–18cm long, 1–5cm wide, oblong to elliptic, coarse in texture, with prominent veins and distinct midrib.
  • Papery, white flowers, 9–11mm wide, produced in clusters where leaf joins stem.
  • Spreading stems sprout new roots from nodes where they contact soil.
  • Larger stems can be quite robust.
  • Fruit is a 2-valved capsule, 14–17mm long.
  • Each capsule has 12–18 seeds.
  • Seeds are pale brown, round, flattened, smooth, 0.3–1mm long.


  • Found along creekbanks and in shallow, freshwater wetlands.


  • Visit the Weeds Australia website and click on the distribution tab to access the distribution map.

Life cycle

  • Flowering and fruit production occurs from December–March.



  • Grows aggressively and competes with native water plants.
  • Forms mats of dense, floating growth at the edges of freshwater lakes.

How it is spread

  • Can spread by floodwaters.


Herbicide control

Legal requirements

  • Hygrophila is a category 3 restricted invasive plant under the Biosecurity Act 2014.
  • You must not give away, sell, or release into the environment. Penalties may apply.
  • You must take all reasonable and practical measures to minimise the biosecurity risks associated with dealing with hygrophila under your control. This is called a general biosecurity obligation (GBO).
  • At a local level, each local government agency must have a biosecurity plan that covers invasive plants in its area. This plan may include actions to be taken on hygrophila. Some of these actions may be required under local laws. Contact your local council for more information.

Further information