|Common name:||khaki weed|
|Scientific name:||Alternanthera pungens Kunth.|
|Other scientific name/s:|
|Other common name/s:|
Catchment management authority boundaries
Regionally prohibited in the North East, East Gippsland, Port Phillip and Western Port Catchments
Regionally controlled in the Wimmera, North Central and Goulburn Broken Catchments
Restricted in the Glenelg Hopkins, Mallee, Corangamite and West Gippsland Catchments
Herbaceous plant - Forb (flowering herbaceous plant - not a grass)
Khaki weed is a prostrate, creeping perennial herb and propagates from an underground organ (geophyte).
Khaki weed stems are reddish in colour. They grow in a prostrate manner and trail to 60 cm long. The stems have fine teeth (visible with a microscope) and soft silky hairs.Several stems grow from each crown with roots formed at stem nodes.
Khaki weed has numerous leaves that grow in opposite pairs of unequal size up to 4 cm long. They are oval shaped, have short stalks and sparsely haired.Veins are prominent on the underside of the leaves.
Flowers of khaki weed are inconspicuous and surrounded by sharply-pointed, chaff-coloured bracts, occurring in clusters in the axils of the leaves.
Fruit is a prickly burr about 1 cm long. They are chaff-coloured.
Growth and lifecycle
Method of reproduction and disperal
Most dispersal occurs when khaki weed's prickly burrs attach to animals, equipment, clothing and tyres. The weed spreads very rapidly along roadsides when cars and vehicles travel on road verges.
Cultivation carries these plants, as well as root fragments, to clean areas where they establish if moisture is adequate.
Rate of growth and spread
Patches can quickly increase in size as new plants form at the stem nodes.
Seedbank propagule persistence
Khaki weed is a prolific seeder. The seeds remain viable for many years.
Khaki weed prefers tropical and subtropical regions. The plant grows mainly on light soils in areas with high temperatures.
It is a troublesome weed in rural towns, occurring on nature strips, playing fields, caravan parks and saleyards. It occasionally invades native pastures on sandy soils but usually does not persist.
The plant prefers moist areas for vigorous growth but can tolerate periods of drought due to its deep tap-root.
The icons on the calendar below represent the times of year for flowering, seeding, germination, the dormancy period of Khaki weed and also the optimum time for treatment.
Impact on ecosystems and waterways
Khaki weed occasionally establishes in native pastures where it out-competes other native species. Its presence has a major impact on ground flora.
Agricultural and economic impacts
The seed heads of khaki weed cause damage to the feet and mouths of animals and causes a skin ailment in cattle. The weed is also believed to be poisonous to animals; they however rarely eat it.
The plant contributes to vegetable fault in wool.
Social value and health impacts
The sharp spines of the khaki weed's heads are a great annoyance to bare-footed children and fruit-pickers and may affect some recreational activities.It is known to cause hay fever, asthma and dermatitis in some people.
Prescribed measures for the control of noxious weeds
- Application of a registered herbicide
- Physical removal
Other management techniques
Changes in land use practices and spread prevention may also support khaki weed management after implementing the prescribed measures above.
Parsons WT & Cuthbertson EG 1992, Noxious Weeds of Australia, Inkata Press, Melbourne and Sydney.
Parsons, W.T. and Cuthbertson, E.G. 2001, Noxious Weeds of Australia, 2nd edn, Inkata Press, Melbourne & Sydney.
Department of Primary Industries, Regionally Prohibited Weed Information Sheet - Khaki Weed, February 2010.