Alligator weed is a State prohibited weed
State prohibited weeds are the highest category of declared noxious weeds in Victoria.
By definition they are either not yet in Victoria, or are here in small numbers, where their eradication is still possible.
All sightings should be reported to Agriculture Victoria immediately by calling 136 186 or emailing firstname.lastname@example.org.
Why is it important to report alligator weed sightings to Agriculture Victoria?
Alligator weed is a native of South America and is regarded as one of the worst weeds. It is a declared noxious weed in all States and Territories of Australia because of its potential to cause harm to the economy and environment.
Infestation mats can cover an extensive area, causing major blockages of waterways that impact on irrigation practices and recreational activities.
How to identify alligator weed
Alligator weed is a perennial herb with stolons that can grow on land or water.
On water it can be free floating or attached to the bank.
On land it can grow upright, creeping amongst other vegetation or grow flat along the ground.
Flowers are papery and ball shaped, silvery-white in colour and grow on individual stalks.
Roots grow from joints in the stem. These can break off and form new plants downstream.
The leaves of alligator weed are bright green and spear shaped. They grow in opposite pairs along a hollow stem.
These can break off and form new plants downstream.
What should you do if you find alligator weed?
If you think you may have seen alligator weed, please contact Agriculture Victoria immediately on 136 186 or send an email to email@example.com.
Please do not attempt to treat or dispose of this weed yourself. Agriculture Victoria will treat, remove and dispose of alligator weed safely, at no cost to the land owner.
Alligator weed has predominantly been found in south east Melbourne backyards, although a few regional backyard infestations have also been detected. Waterway infestations have also been found in Melbourne and in regional Victoria, at Bendigo and Warragul.
Alligator weed is a particularly hard weed to eradicate because it invades both land and water. In waterways, it can grow from plant fragments dispersed from a parent infestation and produce new infestations downstream.
Alligator weed can be mistaken for other species, such as lesser joy weed (Alternanthera denticulata), an Australian native. However, the leaves of lesser joy weed are not as green or glossy as those of alligator weed and the flowers are in the leaf axil, not on flower stalks.
Mukunuwenna or sessile joy weed (Altenanthera sessilis) is also similar, however the leaves are short and round. Mukunuwenna is grown as a vegetable and in the past, alligator weed has been mistakenly grown in its place.
Wandering trad (Tradescantia fluminensis) is also sometimes confused with alligator weed but has an alternating leaf arrangement and not an opposing arrangement like alligator weed.