Quick Facts

Quick facts

• Starburr (Acanthospermum hispidum) is a native plant of Central and South America that is now widely naturalised throughout northern and eastern Australia.
• Starburr is an upright, roughly hairy annual herb that grows up to 1 m high, with stalkless, oval to elliptic or tongue-shaped leaves and small, yellowish green flower heads.
• The fruits develop into a star-shaped prickly burr.
• The bristly burrs cling to animals, clothing and other objects to be transported to other areas.
• The sharp and irritating burrs cause a nuisance, and plants compete with crops, pasture and native vegetation.
• Once introduced, infestations can spread rapidly and persist throughout an area.

What Does It Look Like?

What is it?

Starburr (Acanthospermum hispidum) is an upright, rough to touch (due to being covered with stiff white hairs), branched annual (short lived) herb growing up to 1 m high and is a member of the daisy family. The dull to pale yellowish green leaves are usually opposite, up to 12.5 cm long and mostly 1-3 cm wide, and lack stalks. They are oval to elliptic or tongue-shaped, irregularly shallow-toothed/serrated to lobed on the margins and dotted with glands.

The small green to yellow coloured flower heads are solitary, 4-6 mm wide when in flower (10-18 mm wide in fruit), about 5 mm long and held by a cup of bracts (modified leaves below flower head).The longer inner bracts become spiny and form a star-like burr around the fruits with this appearance giving rise to its common name.

The wedge-shaped fruits are up to 7 mm long and are covered with short hooked prickles as well as having 2 spreading spines at the tip that are stouter and longer than the prickles (Kleinschmidt & Johnson 1977; Friend 1983; Stanley & Ross 1986; Murray 1992; Holm et al. 1997; Hussey et al. 1997; Miller & Schultz 1997; Parsons & Cuthbertson 2001; PIER 2007).

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

Flower colour

Yellow, Green

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Starburr is found in the humid and subhumid tropics in a wide range of habitats and is commonly a weed of disturbed ground and areas, especially near settlements. It occurs on roadsides, in waste places, stockyards, around silos, stock routes, in pastures and cultivation, as well as natural vegetation areas such as grassland and woodland. It is often found on creek flats, alluvial flats and usually on sandy soils, but may also occur on heavier clay soils (Kleinschmidt & Johnson 1977; Stanley & Ross 1986; Murray 1992; Weed Technical Working Group 1999; Parsons & Cuthbertson 2001; Smith 2002).

Are there similar species?

Starburr is characterised by its hairy stem, yellow-green florets, opposite leaves and burr fruits that are arranged in the form of flat stars with hooked spines and with two longer than the rest arising from the apex (Holm et al. 1997). The related Paraguayan Starburr (Acanthospermum australe), also known as Paraguay Burr, Paraguay-bur, Paraquay-starbur or Sheepbur, is a prostrate herb with shorter leaves and the burr lacks the two spreading spines at the tip (Auld & Medd 1992; Murray 1992).

Why Is It A Weed?

What are its impacts?

Starburr is A weed of pastures, crops, disturbed sites, roadsides and waste areas in the warmer (i.e. tropical, sub-tropical and semi-arid) climatic regions of northern Australia (Biosecurity Queensland 2016).

Agriculture: Starburr has various impacts on agriculture. It invades and competes with crops (e.g. sugarcane, pineapple, cotton, soybeans, sunflowers, rice, wheat, peanuts and vegetables in overseas countries; tobacco, sugarcane, maize and sorghum in northern Australia) and pastures, and will take over disturbed land, overgrazed areas, riverbanks and areas around bores and yards (Holm et al. 1997; Miller & Schultz 1997; Parsons & Cuthbertson 2001; Smith 2002). Competition from weeds for space, light, water and nutrients reduces agricultural yields and productivity. Dense patches in pastures reduce the area available for grazing. It is not grazed by stock and it can impede harvesting (Weed Technical Working Group 1999; Parsons & Cuthbertson 2001). It is also contaminant of harvested material such as hay (Miller & Schultz 1997). The seeds and leaves contain chemical compounds called phenolic acids that leach out from them and inhibit germination and the root and shoot growth of some crops (Holm et al. 1997).

The burrs are a troublesome and serious contaminant in wool (Kleinschmidt & Johnson 1977; Parsons & Cuthbertson 2001) and are a possible contaminant of crop and pasture seeds (Friend 1983). The sharp spines on the burr cause discomfort to humans and animals (Miller & Schultz 1997). Its presence in seedling stage at maize-harvesting time is a nuisance to harvesters (Kleinschmidt & Johnson 1977). The burrs injure stock by penetrating the hooves which may lead to the wound getting infected and result in lameness (Parsons & Cuthbertson 2001). The spines can also cause skin lesions (Holm et al. 1997).

Plants may cause stock poisoning due to their nitrate levels (Holm et al. 1997; Parsons & Cuthbertson 2001). It can be toxic to animals, e.g. mice and goats, when consumed daily (Holm et al. 1997).

It acts as an alternative host to a number of plant pests and diseases that attack crops, including the cotton insect pest Calidea dregii, a tomato leaf curl transmitted by white flies, and the wilt-causing pathogen Verticillium albo-atrum (Friend 1983; Holm et al. 1997; Parsons & Cuthbertson 2001).

Native ecosystems: Where Starburr invades natural vegetation it may form dense infestations that out-compete the more desirable native species (Smith 2002). It is known to invade native rangeland pastures and out-compete more desirable native species, particularly along waterways and on nearby floodplains. This not only has a negative impact on the productivity of these pastures but also effects their biodiversity. Starrburr has also invaded national parks and aboriginal lands, where it may cause even more significant environmental damage. For example, it is seen as a threat to the Flora River Nature Park in the northern parts of the Northern Territory because it is common in surrounding areas and could easily invade the park through flood waters, feral animals, wandering stock, vehicles and visitor activities (Biosecurity Queensland 2016).

How does it spread?

Starburr reproduces by seed that is dispersed in the spiny burrs. The burrs have hooked spines that readily adhere to fur, clothing, wool bales and other fibrous materials (Holm et al. 1997; Miller & Schultz 1997; Parsons & Cuthbertson 2001; Smith 2002). Seed can also be spread as a contaminant of hay and fodder, as well as in soil, plant waste and straw and by adhering to vehicle tyres (Weed Technical Working Group 1999; Parsons & Cuthbertson 2001; Smith 2002). The burrs can also float and may be dispersed by water moving down streams and by floodwaters, germinating as the water recedes (Parsons & Cuthbertson 2001; Smith 2002; PIER 2007).

What is its history in Australia?

Starburr may have been introduced to Queensland late in the 19th century. It was recorded as naturalised at Townsville in 1906 and it has subsequently spread: to many parts of Queensland and to northern New South Wales, the Northern Territory and tropical Western Australia. It may have been introduced to the Northern Territory as a contaminant in chaff or hay (Parsons & Cuthbertson 2001).

How To Manage It?

Best practice management

Chemical control: There are many herbicides that can be directly applied to control Starburr (an extensive list is provide heree https://www.cabi.org/isc/datasheet/2465). Please see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Non-chemical control: Isolated plants and small populations can be physically controlled by removing the plants by hand or digging and then burning or deeply burying the material. Monitoring of the area and follow-up controls may be required to remove any new seedlings. Starburr is an annual, so preventing it from seeding will eventually eliminate it. Cultivation or slashing is effective if undertaken prior to seed set, but if left till after seed set these actions could spread the plant instead. Where cultivation is practicable, the field needs to be ploughed to bury any existing seeds at least 10 cm below the surface and then sown with a suitable perennial pasture, preferably a species that provides a dense surface cover and shading. Any weed seedlings sprouting from the newly sown pasture must be removed as soon as practicable. Plants can also be effectively controlled by chemicals (Kleinschmidt & Johnson 1977; Miller & Schultz 1997; Parsons & Cuthbertson 2001).

Quarantine will be an integral part of any control program. All animals brought on to a property, as well as those moved from infested to burr-free parts of the property, must be checked and any burrs removed (Parsons & Cuthbertson 2001). The spread to uninfested 'clean' areas can be controlled by only using hay that is free of the weed and its seed (Miller & Schultz 1997).

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Starburr is an annual herb that flowers and fruits mainly during summer-autumn, with fruiting often occurring into winter (Murray 1992; National Herbarium of New South Wales 2008). Seed is shed when it is fully mature and plants usually die in autumn-early winter. Plants that germinate at the beginning of the growth season tend to produce many dormant seeds, while plants that germinate later in the growth season tend to produce fewer seeds that in turn germinate immediately. Seeds germinate after the first spring or early summer rains or, in moist areas, when temperatures are high enough (20 to 30^oC); and young fertile plants can occur in July-August. Subsequent growth is rapid, with fruit appearing as early as 35 days after emergence and seeds maturing about 45-50 days later. Starburr is a prolific seeder and its seeds remain viable for about 3 years to up to 8 years depending on the depth of burial (Parsons & Cuthbertson 2001).

Where Is It Found?

Which states and territories is it found?

NSW, NT, QLD, WA

What areas within states and territories is it found?

Starburr often grows in areas with summer rainfall. It occurs from mainly north-eastern Western Australia (the Kimberley region), but it is also recorded from Kenwick near Perth and near Karratha, through much of the Northern Territory (especially in the Top End) and Queensland to north-eastern New South Wales (north from Kendall) (Kleinschmidt & Johnson 1977; Stanley & Ross 1986; Murray 1992; Miller & Schultz 1997; Parsons & Cuthbertson 2001; Western Australian Herbarium 2007).

Starburr has been recorded in Victoria on a property in the Maffra-Briagolong region in 2005. This occurrence was the result of seed being transported in peanut straw from Queensland that then germinated in this new area. It is unknown if the species has become naturalised (National Herbarium of Victoria 2008).

It is now widely distributed throughout tropical and subtropical areas of the world (Holm et al. 1997; Parsons & Cuthbertson 2001). It occurs in parts of South, Central and North America, Hawaii, Africa, India, Madagascar, Mauritius, the Caribbean, Thailand, Indonesia, Papua New Guinea and Australia (Holm et al. 1997; Weed Technical Working Group 1999; Parsons & Cuthbertson 2001; PIER 2007).

Where does it originate?

Starburr is native to Central America (i.e. Costa Rica, El Salvador, Guatemala, Honduras and Nicaragua), parts of the Caribbean and tropical South America (i.e. French Guiana, Guyana, Surinam, Venezuela, Brazil, Bolivia, Colombia, Peru, Paraguay, Uruguay and northern Argentina) (Parsons & Cuthbertson 2001; Biosecurity Queensland 2016).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NT, WA

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

Acanthospermum hispidum

Other scientific names (synonyms)?

Does it have other known common name(s)?

Star-burr, Goat's Head, Star Burr, Bristly Starburr, Donkieklits, Sterklits, Upright Starburr, Hispid Starbur, Slingshot Weed, Texas Cockspur