Quick Facts

Quick facts

  • Buchan Weed (Hirschfeldia incana) is an annual or biennial (occasionally perennial), herb that grows up to 100 cm tall and has pale yellow flowers.
  • It is a widespread weed of roadsides and waste places in south-eastern Australia.
  • It can be a problematic weed in winter growing cereals, competing with the crop, interfering with harvesting and contaminating grain.
  • If grazed, Buchan Weed can taint meat and dairy products.

What Does It Look Like?

What is it?

Buchan Weed (Hirschfeldia incana) is an annual or biennial (occasionally perennial), upright erect herb that grows up to 100 cm tall. The stems and leaves are covered in stiff simple (un-branched) bristle-like hairs. The lower leaves are produced en-mass, are up to 350 mm long, deeply lobed to the stem and sometimes toothed, with the terminal lobe being the largest lobe ovate (egg-shaped, with the widest point at the base), with a leaf stalk .The upper leaves are similar in appearance to the lower leaves, but are smaller, diminishing in size, frequency and lobbing along and up the stems, ultimately becoming un-lobed.  Upper leaves on upper stem are un-stalked (sessile), without lobing, oblanceolate (lance shaped, about 4 times as long as broad, broadest in the upper half, tapering to a narrow base), and toothed.

Many 100s of flowers  are produced along many leggy branching stems on the top half of the plant.  Flowers consist of four pale yellow petals that are often purple-veined. Each petal is 6-9 mm long with a surround whorl of 4 green sepals 3–4 mm long. Numerous Flowers are produced at the tip of the flowering branches and are short lived soon becoming fruits that line the long stems.

The fruits are initially green, circular in cross-section (terete, more or less cylindrical) 0.7-17 mm long, 1-1.5 mm wide, at the end of each fruit, there is small beak (3-6 mm long), appressed to the stem (held against the stem), are usually covered in stiff hairs, and are held on a fruiting-stalk 2–5 mm long. Fruits split open with a central membrane with two valves (sides of fruit) that reveals seeds on each side, with valves slightly constricted between seeds, glabrous (without hairs) or hairy, with the small beak (3-6 mm long)  usually containing a single seed. This character gives the fruit a shape similar to an old fashioned clothes peg. The seeds are small, about 0.5 mm diameter and are reddish brown in colour (Hewson 1982; Rich 1991; Entwisle 1996; VicFlora 2016).

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

Flower colour


Growth form (weed type/habit)


Where it currently grows? Preferred habitat

Buchan Weed is a common weed in south-eastern Australia, where it is most often associated with disturbed habitats such as roadsides and wasteland (Auld & Medd 1987, Parsons & Cuthbertson 2001). It also occurs in degraded pastures, orchards and vineyards (Parsons & Cuthbertson 2001).

Are there similar species?

Buchan Weed may be commonly mistaken for several other yellow flowered cruciferous (Brassica-like) species in the genera; Brassica, Diplotaxis, Raphanus, Rapistrum and Sinapis. The fruits of Buchan Weed are usually held against the stem and have a covering of stiff hairs. At the end of each fruit, there is small beak, which usually contains a single seed, this character gives the fruit a shape similar to an old fashioned clothes peg and is a character that should serve to differentiate it from other similar species. Various weed guides, including Richardson et al. (2006), Auld and Medd (1996), Hussey et al. (2007), Navie (2004) and various regional and state floras should be consulted for further information on differentiating between these species.

Why Is It A Weed?

What are its impacts?

Buchan Weed (Hirschfeldia incana) is a weed of open, disturbed habitats in natural, anthropogenic, and agricultural systems, mostly impacting agricultural Pasture and cropping but also a weed of orchards and vineyards. It is a  weed of disturbed urban areas such as roadsides, rail corridors, fence lines,  gardens and parks in the suburbs, yards and abandoned sites, and some disturbed natural environments.

Agriculture: Buchan Weed is one of the crucifer (Brassicaceae) weeds that compete with broadacre crops and pasture in some situations. Buchan weed populations increase when broad-leaf crops, such as oilseed rape and vegetable seed are grown. In pastures it may be present but not obvious due to grazing. When these pastures are cultivated it may dominate unless controlled by grazing, cultivation or herbicides (Government of South Australia 2014). Buchan weed does not normally invade healthy pastures invading poor pastures and if eaten by stock, can taint meat and dairy products (Parsons & Cuthbertson 2001). It is normally only palatable when young, loosing palatability when flowering and fruiting. It can grow in dense stands replacing and limiting desirable species, and the amount of pasture available. It can sometimes be a serious competitor when growing amongst winter cereals, reducing yields as well as interfering with harvesting and contaminating harvested grain (Parsons & Cuthbertson 2001). Also a weed forming dense stands in orchards and vineyards. It has the potential to become a major cropping weed in Victoria (Dellow et al. 2006)a and is regarded as one of the top nine Brassica weeds in South Australia (Dellow et al. 2006).

Native ecosystems: As Buchan Weed is  a weed of disturbed sites it does not normally invade intact native vegetation. However, it can invade disturbed open vegetation, examples being; creek-lines; grassy woodlands, open coastal dense; and especially on margins and tracks of  other native variegation types in agricultural areas where the weed is common.  

Urban areas: Invades roadsides, rail corridors, disturbed areas and parks.

How does it spread?

The sole means of reproduction for Buchan Weed is via the production of seed. Seeds of this weed spread in the same manner as other weedy members of the Brassicaceae family such as Wild Radish (Raphanus raphanistrum) and Sand Rocket (Diplotaxis tenuifolia). The seed is spread by water, especially where plants grow in riparian habitats and on steep terrain where erosion and run-off occurs. Significant vectors for seed transport to new sites occur in contaminated soil, fodder, vehicles and cultivation equipment. Seeds may also be readily dispersed along roadsides during roadside maintenance works. Dispersal via contaminated agricultural produce is another important means of spread (Baker 2008 pers. comm.).

What is its history in Australia?

Herbarium records indicate that Buchan Weed was first recorded in Australia in 1880 from Port Lincoln in South Australia. 

In 1903 it was recorded from Bathurst, New South Wales, and then in 1910 from, Cooma-Monaro.

First recorded in Victoria in 1911 from Moonee Valley.

It was recorded several years later from ACT in Canberra in 1930.

It was first recorded from Queensland in 1966 near Harrisville,

First from Tasmania, from Derwent Valley in 1975 (AVH 2021) and from Hamelin Bay, Western Australia, in 1988 (AVH 2021Western Australian Herbarium 2007).

It is not known how the species arrived in Australia. It was possibly introduced as a contaminant of agricultural produce, such as crop seeds (Baker 2008 pers. comm.).

How To Manage It?

Best practice management

Can be control by herbicides and physical and mechanical methods. Also prevention of seed onto un-infested areas employing good weed hygiene, and dense healthy pastures helps prevents establishment.

Chemical control: Chemical control of Buchan Weed can be successful (Parsons & Cuthbertson 2001) with only a a few herbicides provide effective control of this species, and several of the herbicides used on other annual and perennial members of the Brasicaceae are less effective on H. incana.

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

Non-chemical control: Physical control: Single plants can be hand-pulled, but care must be taken to remove as much of the taproot as possible because plants readily re-shoot from pieces of root left in the soil (Parsons & Cuthbertson 2001).

Mechanical control: Deep ploughing effectively controls Buchan Weed by burying the taproot, with further cultivation usually required to control seedlings that subsequently emerge.

Competition and management: Sowing with a vigorous pasture species should prevent re-infestation (Parsons & Cuthbertson 2001). Although neither method has been tested for the management of H. incana, grazing or prescribed burning are not expected to be effective for the control of this species (DiTommaso et al., 2013).

Does it have a biological control agent?


When does it grow? (lifecycle/growth calendar)

Buchan Weed (Hirschfeldia incana) is an annual (lives for one year) or biennial (a plant that lives for two years) and occasionally perennial (a plant that lives for over two years) herb. Seeds of Buchan Weed lie dormant for about one month after being shed. Seeds germinate throughout autumn and grow slowly until mid-winter when flowering stems develop. Flowering starts in September and continues through to February. The stems and leaves die down at this time. New growth comes from the rootstock when autumn rains return (Parsons & Cuthbertson 2001).

Where Is It Found?

Which states and territories is it found?


What areas within states and territories is it found?

Buchan Weed is a widespread weed in south-eastern Australia and is naturalised in Queensland, New South Wales, Victoria, Tasmania and South Australia.

In South Australia, it is common in the south-east of the state, including around Adelaide all the way to the Victorian border to the the South East, and lower Eyre Peninsula  (eFlora 2021).

In Victoria, it is occurs mainly around the eastern districts, in particular the north east, Gippsland and central regions (VicFlora 2016).

In Queensland, it is confined to the south-east of the state (AVH 2021).

In New South Wales, it has spread throughout the Central Coast, Southern and Central Tablelands, Central Western and North Western Slopes, and the North Western and South Western Plains regions (National Herbarium of New South Wales 2007).

In Tasmania, it is a common roadside weed around Hobart and it has been recorded on King Island (Baker 2008 pers. comm.).

In Western Australia, the species is known only from one record at Hamelin Bay in the State's south-west (Hussey et al. 2007).

Where does it originate?

Buchan Weed is native to the Mediterranean region (Hewson 1982).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?


Where is it a declared weed?


Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?


Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?


Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Hirschfeldia incana

Other scientific names (synonyms)?

  • Brassica adpressa Boiss.
  • Brassica geniculata (Desf.) Benth.
  • Brassica incana (L.) Meigen
  • Hirschfeldia adpressa Moench
  • Sinapis geniculata Desf.
  • Sinapis incana L.

Does it have other known common name(s)?

Hairy Brassica, Hoary Mustard, shortpod mustard.

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