Weeds of Australia - Fact Sheet

Top Scientific Name Synonyms Family Common Names Origin Naturalised Distribution Notes

Scientific Name

Hygrophila polysperma (Roxb.) T. Anderson

Synonyms

Justicia polysperma Roxb.

Family

Acanthaceae

Common Names

dwarf hygrophila, East Indian hygro, East Indian hygrophila, East Indian swampweed, green hygro, hygro, hygrophila, Indian swamp weed, Indian swampweed, Indian water star, Miramar weed, oriental ludwigia

Origin

Native to the Indian Sub-continent (i.e. Bangladesh, Bhutan, India and Nepal) and south-eastern Asia (i.e. Cambodia, Laos, Myanmar, Thailand and Vietnam).

Naturalised Distribution

Currently only naturalised at a few locations in south-eastern Queensland and north-eastern New South Wales.

Also naturalised overseas in eastern USA (i.e. Florida, Texas and Virginia).

Notes

East Indian hygrophila (Hygrophila polysperma) is regarded as an emerging environmental weed in Queensland and New South Wales. This species was first collected in Australia in August 2005 in the Caboolture River north of Brisbane. It was growing along the riverbank and in the water, both as a submerged aquatic and terrestrial plant. East Indian hygrophila (Hygrophila polysperma) is thought to have escaped cultivation as an aquarium plant and has since been found along the Tweed River and Clarence River in coastal northern New South Wales and along Enoggera Creek in suburban Brisbane.

This species has the potential to become a serious weed of freshwater lakes, ponds and dams in eastern Australia. It prefers flowing water in warmer environments, but may also be found in slow moving waters and lakes. East Indian hygrophila (Hygrophila polysperma) is fast growing invasive plant that out-competes native aquatic plants. It can occupy the entire water column and also creates problems as an emergent plant along the margins of waterbodies.

East Indian hygrophila (Hygrophila polysperma) has replaced hydrilla (Hydrilla verticillata) as the major aquatic weed in some parts of Florida, and is considered by the state's Exotic Pest Plant Council to be one of the most invasive non-indigenous aquatic plants in this part of the USA. It forms dense stands and floating mats of vegetation in waterways, canals and drainage ditches, which obstruct water flow and displace native vegetation. Its ability to form a dense canopy at the water-air interface is of particular concern, because this enables it to shade out all other submerged plants.