Parrot's feather: declared pest

Page last updated: Thursday, 10 October 2019 - 1:02pm

Please note: This content may be out of date and is currently under review.

Parrot's feather, Brazilian water milfoil (Myriophyllum aquaticum) is a declared pest in Western Australia (WA). This article describes the nature of the plant with links to requirements land owners/occupiers must adhere to and pest control methods.

Form: aquatic

Status: present in WA


A bright green perennial freshwater herb that grows from the banks or rises up through several metres of water, forming vigorously-growing tangled mats. Reproduction in Australia is only by vegetative means. Recorded from Perth, Busselton and Margaret River.

Stems: Yellow-green and slender, two to five metres long, creeping and rooting at the nodes near the base of the plant.

Leaves: Bright green, feathery in appearance, in groups (whorls) of four to six, becoming more densely crowded towards the top of the stem. Each leaf is linear to elliptical in outline, 3-3.5 centimetres long, deeply divided into 10 to 14 pairs of thread-like segments.

Flowers: Solitary, arising on short stalks between two small bracts about 1.5 millimetres long in the upper leaf axils. Petals are absent, sepals (outermost parts of the flower) four in number, white-translucent and 1-1.5 millimetres long.

Agricultural and economic impact

An environmental water weed, it can block irrigation channels.

Declared pest category

The Western Australian Organism List (WAOL) contains information on the area(s) in which this pest is declared and the control and keeping categories to which it has been assigned in Western Australia (WA). Use the external links on this page to reach parrot's feather in WAOL.

Requirements for land owners/occupiers and other persons

Requirements for land owners/occupiers and other persons if this pest is found can be sourced through the declared plant requirements link.

Search > detect > report

Report: this pest by using the MyWeedWatcher smartphone and tablet application or online reporting tool.

Control method

Control methods for this declared plant can be found through the parrot's feather control link.

Contact information

Pest and Disease Information Service (PaDIS)
+61 (0)8 9368 3080