Limnocharis

Alert

Have you seen Limnocharis?

Be on the lookout for Limnocharis and report it to Biosecurity Queensland. Early detection and reporting are the key elements in preventing Limnocharis from becoming a major problem in Queensland.

Call us on 13 25 23.

Native to Central and South America (including Mexico, Bolivia, Paraguay and northern Argentina), limnocharis is an anchored aquatic plant. Limnocharis colonises wetlands, restricting water flow and displacing native plants and animals.

Limnocharis is an introduced weed in southern USA and parts of Asia. It is a serious agricultural and biodiversity threat to northern Australia, including the Northern Territory, northern Western Australia, and much of eastern Queensland. Infestations in northern Australia have been found in backyard ponds, ornamental lakes, farm drains and natural waterways.

You must manage the impacts of Limnocharis on your land.

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

You must report all sightings to Biosecurity Queensland within 24 hours.

Scientific name

Limnocharis flava

Other names

  • Bur head, sawah flower rush, sawah lettuce, velvetleaf, yellow burr head

Description

  • Anchored aquatic plant with erect stems (leaves do not lie flat on surface of water body).
  • Plants grow up to 1m above the waterline.
  • Leaves are pale green, velvety, up to 28cm long and 20cm wide, with 11–15 parallel veins.
  • Leaf blade shape varies with age; fairly narrow when young then more oval as plant ages.
  • Triangular stem is a key identification feature (most aquatic plant stems are round) and can be up to 85cm long.
  • Three-petalled yellow flowers are yellow, cup-shaped, on triangular stalks.
  • Each stalk produces 2–15 flowers.
  • Spherical capsules produced after flowering split into 12–18 crescent-shaped pieces called follicles, which may contain up to 115 small brown seeds.

Habitat

  • Grows in saturated, fertile and muddy conditions.
  • Grows as a perennial plant in areas with sufficient moisture.
  • Frost-sensitive as a tropical species.

Distribution

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

Life cycle

  • Can flower year-round.
  • Reproduces by seed and vegetatively from plantlets, detached leaves and stems.
  • Mature fruit can be produced in as little as 46 days. Seeds contained in mature fruit capsules or individual follicles are buoyant and can be distributed by running water.
  • To reproduce vegetatively, ageing fruit capsule bends towards water, allowing seeds to escape. Empty capsule can then develop into vegetative plantlet that either establishes beside parent plant or floats away to establish elsewhere.

Affected animals

  • Native animals
  • Livestock

Impacts

Environmental

  • Colonises shallow wetlands and margins of deeper waterways.
  • Displaces native plants and animals.
  • Restricts water flow and traps silt.

Social

  • Restricts human and livestock access to water.
  • Provides breeding areas for mosquitoes.

How it is spread

  • Seeds spread by running water, waterbirds and animals.
  • Also spread by mud sticking to vehicles, machinery and footwear.

Control

Phone 13 25 23 if you find a plant you suspect may be limnocharis to seek advice on control options.

Physical control

  • Limnocharis is the target of a national eradication program.
  • New infestations must:
    • be reported to Biosecurity Queensland on 13 25 23
    • be identified and removed by approved officers
    • have their locations recorded prior to removal.

Herbicide control

  • No herbicides are registered to specifically control limnocharis.

Biological control

  • No known biological control agents.

Legal requirements

  • Limnocharis is a category 2, 3, 4 and 5 restricted invasive plant under the Biosecurity Act 2014.
  • You must not keep, move, give away, sell or release limnocharis into the environment. Penalties may apply.
  • You must report all sightings to Biosecurity Queensland within 24 hours.
  • You must take all reasonable and practical measures to minimise the biosecurity risks associated with dealing with limnocharis under your control. This is called a general biosecurity obligation (GBO).
  • At a local level, each local council must have a biosecurity plan that covers invasive plants and animals in its area. This plan may include actions to be taken on limnocharis. Some of these actions may be required under local laws. Contact your local council for more information.

Further information