Alligator Weed, Alternanthera philoxeroides, has been spotted for the first time in the Upper Manning River at Tibbuc.
Left uncontrolled Alligator Weed is a potentially devastating terrestrial and aquatic weed capable of negatively impacting the agricultural and biodiversity values of a region. Found primarily along rivers, creek and around dams; it is also capable of surviving in drier conditions and competing with pasture.
Alligator weed is a summer growing herb. It has small white papery flower heads 8–10 mm in diameter, generally appearing from November to March. The flowers grow at the end of short stalks which rise from the leaf axils. Alligator weed has leaves occurring in opposite pairs along it’s hollow stems. The leaves are shiny, spear-shaped, sessile (no stalk), entire and about 2–7 cm long and 1–2 cm wide.
Alligator weed has an extensive underground root system. Roots are relatively fine and short in water but become thicker, starchy and rhizome-like in soil, able to penetrate to depths of over 50 cm. Roots and stems have been found growing more than 1 m below the surface. Root storage tissues allow for survival over long dry periods.
For more information, see NSW Weedwise
Alligator weed is a state priority weed, landowners and managers should remain vigilant monitoring river frontages and flood affected pastures. Invasion of pastures, irrigation equipment and pumps can become costly problem if not managed early. Local sightings should be reported to MidCoast Council’s weeds team;
Will McCaffrey will.mccaffrey@midcoast.nsw.gov.au
Ujwal Minocha ujwal.minocha@midcoast.nsw.gov.au
