Quick Facts

Quick facts

• Originally from Southern America, Khaki Weed (Alternanthera pungens) is a fairly hardy species that is adaptable to dry and moist conditions.
• It successfully invades a variety of habitats, particularly in degraded areas and around towns and is a weed of agriculture.
• The sharp spiny fruit cause mechanical damage to the feet and mouths of stock and working animals when present in hay and pasture.
• The nature of the spiny fruit is such that once embedded in rubber soled shoes or tyres it can travel great distances to new potential habitat.
• Its spiny presence in lawns, caravan parks, recreation areas, nature strips and orchards creates great annoyance to humans frequenting these areas.
• Can be controlled by herbicide and cultivation of soil

What Does It Look Like?

What is it?

Khaki Weed (Alternanthera pungens) is a prostrate (matt forming) creeping perennial (occasionally annual) herb with a deep woody taproot. The spreading stems are up to 500 – 600 mm long, reddish with soft silky hairs, often forming extensive mats and rooting at the nodes (leaf joints on the stem). Leaves are in opposite pairs of unequal size, 10-40 mm long, 10-20 cm wide, obovate (egg-shaped with the widest part near the tip) or circular, occasionally ovate (egg-shaped with the widest part near the base). Leaves are hairless or sparsely hairy especially near the base, prominently veined on underside, and shortly petiolate (with a short leaf stalk). Leaf margins are entire (without teeth), often with a short point at the tip VicFlora (2016).

The flowers are in axillary ovoid clusters, 6-10 mm long. Flowers surrounded by 3 bracts (leaf-like structures) and bracteoles 2–3 mm long, and are clustered together in between the leaves and the stem. The spikes are white, yellow or greenish when young and become straw coloured when mature. Each flower is 3.5–5 mm long and has 5 unequal segments with the 2 longest segments sharply pointed.

The fruit matures within the flower segments and bracts and the entire spike then detaches from the stem forming a prickly burr to about 10 mm long. This then breaks up into individual prickly fruit. There is one yellowish amber or brown, globular seed per fruit, 1-3 mm diameter (Miller & Schultz 1997; Parsons & Cuthbertson 2001; Navie 2004).

Recognition: This species can normally be recognised by the combination of the following characters; an annual prostrate (matt forming) herb; leaves – opposite pairs of unequal size, 10-40 mm long, 10-20 cm wide egg-sapped, deep green, hairless or sparsely hairy leaves; cream flowers are in ovoid clusters, 6-10 mm long with sharp points.

For further information and assistance with identification of Khaki Weed, contact the herbarium in your state or territory.

Flower colour

White, yellow or green.

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Khaki Weed (Alternanthera pungens) is found in tropical and subtropical regions growing mainly on light soils in areas of high temperatures. It also grows in cool temperate areas in southern Australia. Khaki Weed does particularly well colonising bare or disturbed areas and can be found in and around towns commonly occurring on nature strips, lawns, playing fields, caravan parks and saleyards (Parsons & Cuthbertson 2001). It is also found along road verges, crop and farm land, degraded pastures and disturbed natural vegetation (Spooner et al. 2007).

Are there similar species?

Khaki Weed (Alternanthera pungens) is somewhat similar to Bindy Eye (Soliva sessilis) and some of the Joyweeds (e.g. Alternanthera denticulata, Alternanthera nodiflora and Alternanthera nana). It is also similar to Gomphrena Weed or Soft Khaki Weed (Gomphrena celosioides) (Navie 2004), and small matweed (Guilleminea densa). 

Gomphrena weed (Gomphrena celosioides) and small matweed (Guilleminea densa) may be distinguished by their lack of prickles, and gomphrena weed (Gomphrena celosioides) also by its larger whitish flower clusters that are borne at the tips of its branches (Brisbane City Council 2020).

Bindy Eye (Soliva sessilis) is a low-growing (i.e. prostrate) plant that produces prickles from its flower parts. However this species has very different, highly divided, leaves. Lesser Joyweed (Alternanthera denticulata), Common Joyweed (Alternanthera nodiflora) and Hairy Joyweed (Alternanthera nana) may have a low creeping habit and very similar flower clusters to Khaki Weed, but these species do not produce prickles. Gomphrena Weed may also be distinguished by its lack of prickles and by its larger, whitish-coloured, flower clusters that are borne at the tips of its branches (Navie 2004).

Why Is It A Weed?

What are its impacts?

Khaki Weed (Alternanthera pungens) is a thick ground cover with spiny burrs that can injure people and animals. It is claimed to also cause hay fever, asthma and dermatitis in some people (Parsons & Cuthbertson 2001).

Agriculture: It can contaminate crops and devalue wool (DPI NSW 2019). In New South Wales Khaki Weed competes with both irrigated and dryland lucerne crops and the spiny burrs contaminate lucerne hay (Parsons & Cuthbertson 2001). Khaki Weed is seldom a problem in well managed sown pastures but establishes occasionally in native pasture where it out-competes most other species (Parsons & Cuthbertson 2001).  The sharp spines of the fruit cause mechanical damage to the feet and mouths of stock and dogs and contribute to faults in wool (Parsons & Cuthbertson 2001). Khaki Weed is believed to be poisonous to animals and to cause skin aliment in cattle. It is not readily eaten but sometimes young plants are consumed by sheep, apparently without ill effect (Parsons & Cuthbertson 2001).

Urban areas: The deep tap root enables plants to survive drought conditions, but ample moisture in well irrigated recreation areas and caravan parks leads to vigorous growth. Attachment of the spiny fruit to animals, human footwear and car tyres is an important method of transport allowing Khaki Weed to quickly invade lawns, parklands, around bores, along river banks and wasteland areas (Miller & Schultz 1997; Parsons & Cuthbertson 2001). Widespread in wasteland, caravan parks, and recreation areas. Spines are a problem with dogs and stock but are particularly troublesome to humans and readily penetrate skin (DPI NSW 2019).  Barefooted humans also suffer from the spines penetrating the skin.  (Parsons & Cuthbertson 2001).

Native ecosystems: Not a known weed in native vegetation in Southern Australia but can be a weed in and occasionally also native pastures and grasslands and is regarded as an environmental weed in large parts of northern Australia (i.e. in northern Queensland, the Northern Territory and northern Western Australia (Brisbane City Council 2020; DEEDI 2020).

How does it spread?

The seeds of Khaki Weed are dispersed either as a prickly burr of many fruit or as individual spiny fruit. In both instances they can easily attach to animals, equipment, clothing, rubber soled shoes and tyres. Stems of Khaki Weed also root at the nodes so patch sizes can increase greatly. Any sort of cultivation can carry stem and root fragments to other areas and given adequate moisture they can easily become established (Miller & Schultz 1997; Thorp & Wilson 1998; Parsons & Cuthbertson 2001).

What is its history in Australia?

Khaki Weed was first recorded in New South Wales in 1898 but the circumstances of its introduction are not known. Its association with horses returning from the South African War (the Boer War) is suspected for later introductions. It was recorded in Queensland by 1910 and has been known around Alice Springs in the Northern Territory since 1957 (Parsons & Cuthbertson 2001).

How To Manage It?

Best practice management

Khaki Weed (Alternanthera pungens) can be controlled by chemical and physical methods. Care should be taken when mowing and walking through infested areas as this will spread the seed (Miller & Schultz 1997).

Chemical control: Several chemicals are also available to control this weed (DPI NSW 2019; Miller & Schultz 1997; Parsons & Cuthbertson 2001) and can be used as foliar spray. Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Non-chemical control: Physical control: Hand hoeing is effective if the bulk of the tap root can be removed. (Parsons & Cuthbertson 2001). Weeds, including their roots, are physically pulled out of the ground by hand or using hand tools. This is an effective method of control for individual weeds and recent outbreaks that haven’t released seeds yet, but it requires a lot of labour.

Cultivation: Cultivation of the soil will destroy seedlings and established Khaki Weed plants but roots must be cut well below the soil surface to reduce the chance of regrowth. Follow-up cultivation is necessary to destroy new seedlings and any pieces of the new plants that survive.

Fire: Burning of an area after removal is effective in reducing the seed population.

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Seeds germinate after spring and summer rains. A stout taproot and prostrate stems then develop during late spring and summer. Roots form at stem nodes producing new plants and a dense ground cover. Plants flower and seed in summer and autumn and the aerial growth dies off by late autumn. New shoots are produced from the crown each spring (Parsons & Cuthbertson 2001).

Where Is It Found?

Which states and territories is it found?

ACT, NSW, NT, QLD, SA, VIC, WA.

What areas within states and territories is it found?

Khaki Weed occurs in all mainland states and territories. In New South Wales it occurs in towns in a broad band running north to south through the state and Australian Capital Territory, in coastal areas north of Sydney and also agricultural regions in the central and north-west of the state. In Victoria and South Australia, Khaki Weed is confined to towns in the more arid areas (Parsons & Cuthbertson 2001). In the Northern Territory, it occurs in the Darwin, Gulf, Katherine, Victoria River and Alice Springs districts (Miller & Schultz 1997). Khaki Weed is widespread in Queensland particularly around towns in the south-east (Parsons & Cuthbertson 2001). In Western Australia, Khaki Weed can be found in and around towns in the Kimberley and Pilbara regions and around Perth and other centres in the south-west (Spooner et al. 2007).

Where does it originate?

Khaki Weed is native to Southern America, from Brazil, Ecuador, Peru and Venezuela (Thorp & Wilson 1998 -). It has become widely distributed throughout the temperate and tropical world (Parsons & Cuthbertson 2001).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NT, SA, VIC.

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Alternanthera pungens

Other scientific names (synonyms)?

• Achyranthes repens L.
• Alternanthera achyrantha var. echinata (Sm.) Maiden
• Alternanthera achyrantha var. leiantha Seub.
• Alternanthera echinata Sm.
• Illecebrum achyrantha L.
• Alternanthera achyrantha (L.) Sweet (misapplied by Maiden, J.H. 1910, Agricultural Gazette of New South Wales. 21: 1001.)
• Alternanthera repens (L.) Link (misapplied by White, C.T. 1934, Queensland Agricultural Journal Series 2. 42: 583-584, t. 241.)

Does it have other known common name(s)?

Creeping Chaffweed, Khakiklits