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Alligator weed

Weed Habitat 

  • Native to South America, Alligator weed is an extreme threat to freshwater wetlands and river systems throughout much of Australis.
  • Reproduces via fragments of stem dispersed by flowing water, seed is rarely viable.
  • Tolerant of low level salinity.


  • Perennial plant to 7cm high, grows as a trailing terrestrial or floating aquatic herb.
  • Dark green leaves in opposite pairs along hollow stems, spear-shaped with distinct midrib and smooth edges, no leaf stalk.
  • Small white flowers, papery to touch, carried on short (2-7mm) stalks in leaf axils.
  • On land, produces underground stems to a depth of 1m.
  • Forms sprawling interwoven mats to 1m thick in aquatic situations.


Plant Type

Leaf Arrangement

Other weed identifiers

Plant Life Cycle

Weed Declaration

This species is declared Restricted Matter under the Biosecurity Act 2014
For further information on declaration refer to your Local Government or the Department of Agriculture and Fisheries
It is also a Weed of National Significance.

Weed Spread