Quick Facts

Quick facts

• Originally from Mediterranean region through Asia Minor to western Asia, Onion Weed (Asphodelus fistulosus) is an upright annual to short-lived perennial herb
• Soft herb with a flowering stem growing to 80 cm high. It has hollow leaves and 6-petalled white or pink flowers with a brown or reddish stripe along the centre of each petal.
• It occurs on roadsides, railway lines, neglected areas and poorer pastures, in semi-arid areas and sandy coastal environments across most of Australia.
• Onion Weed invades degraded areas and degraded pastures, is unpalatable to livestock, competes successfully with cereal crops and invades relatively undisturbed woodland.
• Onion Weed may be controlled manually by hand-pulling or cultivation, or with the use of herbicides.
• Does not invade well managed pastures or cropping lands.
• Onion Weed can be confused with the closely related Trachyandra divaricata and other non-related species, also commonly known as 'Onion Weed'.

What Does It Look Like?

What is it?

Onion Weed (Asphodelus fistulosus) is an upright, biennial or short-lived perennial sometimes annual herb, with a flowering stem to 80 cm high. Roots are fibrous and yellow in colour. The many leaves, sometimes a hundred or more are hollow, round, 33–50mcm long to 1.5–4 mm wide, all growing from the base of the plant, minutely scabrous (rough to the touch) along margins, often somewhat glaucous ( blue-green in colour with a whitish bloom). Although it is called Onion weed it has no onion smell.

The flowers are arranged alternately along the branches of the flower stem in a panicle (a flower spike in which the flowers are borne on branches of the main axis or on further branches of these). Flowers are borne individually and are white or pink, 15-20 mm diameter, with 6 petals shortly fused at the base, each with a brown or reddish stripe along the centre. The flower stem is hollow, 30-800 mm long, 2.5–7 mm diameter and branched towards the top. The anthers (pollen producers) are orange.

The fruit is an almost globular capsule, wrinkled, 4–7 mm diameter, pale red-brown to sandy-brown, with 3-6 brown or black seeds, 3-4 mm long, wrinkled and pitted. (Godden 1993; Parsons & Cuthbertson 2001; Storrie 2003).

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

Flower colour

White or Pink

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Onion Weed occurs on roadsides, railway lines, neglected areas and poorer pastures, in semi-arid areas and sandy coastal environments. It establishes most readily in disturbed situations where there is little competition and shows a distinct preference for sandy alkaline soils of low fertility and in areas with an annual rainfall of 250-500 mm, usually with a winter dominance (DAFWA 2007; Parsons & Cuthbertson 2001). Onion Weed will establish readily in areas disturbed by cultivation such as roadside grading and cable laying trenches (DAFWA 2007).

Are there similar species?

In Western Australia and South Australia, Onion Weed (Asphodelus fistulosus) is often confused with the closely related Strapweed or Dune Onion Weed (Trachyandra divaricata) (DAFWA 2007; Rippey & Rowland 2004), also an introduced weed. Onion Weed can be distinguished from this species as its leaves are hollow and upright, rather than flat and sprawling as in Dune Onion Weed, and having a flower head that is narrow and compact, rather than much-branched and wide-spreading as in Dune Onion Weed (Rippey & Rowland 2004).

A number of different, unrelated species have the common name 'Onion Weed'. These include Allium triquetrum and Nothoscordum borbonicum [as Nothoscordum gracile], which are mostly weeds of gardens and cultivation, and Romulea rosea, which is a weed of lawns, pastures and woodlands.

Asphodelus fistulosus is the only one of these with cylindrical hollow stems and the only one of these that doesn't grow from bulbs or corms. Of these four species, Allium triquetrum is the only one that smells of onion or garlic when the leaves are crushed (CRC for Australian Weed Management 2003). Individual weed profiles for other species known as 'Onion Weed' are also available on this web site.

Why Is It A Weed?

What are its impacts?

Onion Weed (Asphodelus fistulosus) establishes in disturbed situations, favouring alkaline sandy soils. It is a weed of overgrazed pastures and rangelands, degraded and open native vegetation and coastal areas, along roadsides and tracks and some other native habitats. For example, it has been observed to invade relatively undisturbed open woodland communities as well as dry coastal vegetation, mallee shrubland, lowland grasslands, grassy woodlands and rocky outcrop vegetation. (Queensland Government 2016), and is now widespread and common from coast to arid inland (DPI NSW 2019).

Agriculture: A weed of cereal crops and a major threat to arid rangelands. Because of its prolific seed production and tolerance of dry conditions, Onion Weed invades degraded pastures, competing strongly with other species. It is unpalatable to livestock, so the carrying capacity of grazing land is significantly reduced (Storrie 2003). Overcropping or overgrazing allows Onion Weed to dominate by lowering fertility and degrading natural pastures. Low soil nitrogen is a critical factor that prevent other plants growing on areas dominated by onion weed. It is a very conspicuous pioneer plant on bare sandy soils and rapidly occupies paddocks where the pasture has become sparse, leading to an assumption that it was a cause of the pasture's decline. On abandoned farmland in the Victorian mallee region, it is one of the species that dominates at first but declines as the native vegetation regenerates and almost disappears after about 5 years. It does not compete effectively with vigorous pasture, and cannot dominate where sustainable farming systems are practiced (Government of South Australia 2015).

Onion Weed is of value to the honey industry, producing plentiful pollen which is important when establishing hives (Parsons & Cuthbertson 2001).

Native ecosystems: It will also invade relatively undisturbed woodland (Storrie 2003), but thrives in degraded and open native vegetation on stony or sandy calcareous soils. Onion Weed does not invade undisturbed dry mallee vegetation due to the competition from the root systems of established trees and shrubs, but does invaded some open dry inland native vegetation that have been degraded by decades over grazing, or on the edge of intact healthy vegetation  Invades roadside vegetation, especially in dry or some coastal areas.

Urban areas: Common along roadsides, abandoned land, and open degraded dry areas, especially on stony or sandy calcareous soils. It is thought to cause dermatitis in some people (Parsons & Cuthbertson 2001).

How does it spread?

Onion Weed reproduces wholly by seed which is dispersed mainly by the wind, blowing dead plants that still bear seeds. Seed may also be spread by water, on vehicles, farm machinery, animals, wool, clothing, and in produce (Parsons & Cuthbertson 2001).

What is its history in Australia?

The earliest Australian records of Onion Weed are from the Botanic Gardens in Melbourne and Adelaide, where it was grown in 1857 and 1858 respectively, probably having been introduced as an ornamental species (Parsons & Cuthbertson 2001). The earliest collection of wild plants as weeds from these states was 1881 for South Australia; and 1884 for Victoria. The first collections for WA and NSW was in 1907 (AVH 2021) and collections from most other states followed within a decade.

How To Manage It?

Best practice management

Onion Weed (Asphodelus fistulosus) may be controlled manually or with the use of herbicides.  Prevention of spread, and targeting new infestations, is the best management approach with this species (Storrie 2003).  Onion Weed does not (or rarely) invade well managed pastures or cropping areas.

Chemical control: Onion Weed may be controlled with the use of herbicides. Several herbicides are registered for the control of Onion Weed. Broad scale use of the herbicides is expensive and research is continuing to test for products that will either control the plant or inhibit seed production to restrict the spread (DAFWA 2007). For further information please see: DPI NSW (2019); Western Australian Herbarium (1998–). 

Please see the Australian Pesticides and Veterinary Medicines Authority for further chemical information http://www.apvma.gov.au .

Non-chemical control: Physical control: Onion Weed may be controlled manually by hand-pulling or cultivation.

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Onion Weed seeds germinate all year round, but mainly in late summer and autumn. Plants do not usually flower until they are about 18 months old. Flowering occurs from June to October (Paczkowska 1994) after which the flower stems die back but most leaves remain alive through summer. In the following autumn, new leaves and stems are produced from the base of the plant. Under favourable conditions, some plants flower and die in the first year and are annuals, while others become biennials or short-lived perennials (Parsons & Cuthbertson 2001). The seeds are thought to remain viable in the soil for many years (Storrie 2003). In the more arid areas, many Onion Weed seedlings fail to survive the first summer, but of the surviving seedlings, once established, they are quite drought-hardy (Parsons & Cuthbertson 2001).

Where Is It Found?

Which states and territories is it found?

Found in all Australian state and territories.

What areas within states and territories is it found?

Onion Weed has been widespread in the Victorian mallee and South Australia since the 1930s. By the early 1980s, it was recognised as a problem north of Carnarvon in Western Australia, and is now found from Exmouth to Eucla. In New South Wales, where it continues to spread, it was first seen in the Carrathool Shire in the mid 1980s, having spread from south-western New South Wales. It was first found in the Northern Territory in 1974 (Storrie 2003). Scattered infestations are also found in south-eastern Queensland (Navie 2004). The distribution of onion weed in Tasmania is relatively limited at this time. It occurs as an occasional weed on King Island, Flinders Island and around Hobart (DPIW 2008).

Where does it originate?

Onion Weed is native to the Mediterranean region through Asia Minor to western Asia and northern India (Parsons & Cuthbertson 2001).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NT, TAS

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

Asphodelus fistulosus

Other scientific names (synonyms)?

Does it have other known common name(s)?

Asphodel, Hollow-stemmed Asphodel, Wild Onion