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Mouse-ear hawkweed (Pilosella officinarum)

Mouse-ear hawkweed is a prohibited invasive plant recorded in alpine areas of NSW, including the South East and Murray regions. It forms dense mats that threaten native biodiversity and can reduce pasture productivity.

Key facts

Type: Weed, herb.

Native to: Northern and central Europe.

Established in: NSW, VIC, TAS.

Other names: Hieracium pilosella.

Identification

  • This perennial herb grows up to 30 cm tall, usually 10–20 cm, and releases milky sap when its stems or leaves are broken.
  • Its hairy leaves form a rosette and may also grow along stolons; they are dull green above and whitish underneath.
  • Pale yellow, daisy-like flowers are 1–2 cm across and usually occur singly on unbranched stems, mostly in spring and summer.
  • Hairy stolons grow horizontally above ground, reach up to 30 cm long and form roots at their nodes.
  • Look-alike: Wall hawkweed is taller and has stalked leaves; king devil hawkweed is taller and has multiple flowers on branched stems. Dandelions have often deeply lobed leaves, while flatweed has deeply toothed or lobed leaves; neither has stolons.
  • Look-alike: When young, mouse-ear hawkweed can resemble native felted buttercup, but felted buttercup leaves are up to 3 cm long and lack the pale underside, and its flowers have five petals and are up to 3.5 cm across.

Where it grows

In NSW it occurs in alpine areas of the South East and Murray regions, including grasslands, eucalyptus woodlands with grassy understorey and pastures, often where soil has been disturbed.

Why it matters

  • Dense mats can outcompete native plants in native grasslands and reduce food and habitat for native animals.
  • It competes with pasture plants and reduces grazing productivity.
  • It can invade gardens and roadsides and increase soil acidity.
  • It is a threat to biodiversity in Australia's alpine regions.

How it spreads

  • Plants spread in dense mats through rhizomes and stolons, and new plants can grow from root fragments.
  • Infestations can produce up to 40,000 seeds per square metre; some seeds remain viable in soil for up to five years, and plants can mature in about five months.
  • Seeds can travel by wind and water, attach to boots, clothing, recreational gear, animals, vehicles, ski machinery and slashers, or move with contaminated seed.

Control options

  • Do not attempt to treat or dispose of this weed yourself.
  • Report any sighting immediately to the NSW Biosecurity Helpline on 1800 680 244; all species in the genus Pilosella are Prohibited Matter.
  • NSW DPIRD, Agriculture and Biosecurity will lead the initial treatment and disposal response.

Hygiene and washdown

  • Check and clean boots, clothing, camping and recreational gear, vehicles and machinery to avoid carrying seeds to new sites.
  • Avoid moving contaminated seed, soil or plant material.
  • Inspect and clean vehicles, plant and footwear before leaving an infested area, paying attention to tyres, radiators, belly plates, tracks and floor mats.
  • Wash down at a designated bay where runoff is contained and can be monitored for seedlings.
  • Record each washdown so the client has evidence of clean entry and exit.

Classification by state

  • Australia (national): National priority exotic pest. On the National Priority List of Exotic Environmental Pests, Weeds and Diseases, so any new detection should be reported straight away.
  • Queensland: Not prohibited or restricted. Not listed as prohibited or restricted matter in Queensland. Everyone must also take all reasonable and practical steps to minimise its risks (the general biosecurity obligation).
  • New South Wales: Prohibited matter. It is an offence to deal with it, and you must notify NSW DPIRD as soon as you become aware of it.
  • Victoria: State prohibited weed. State prohibited weeds are the highest priority: the Victorian Government is responsible for eradicating them, so report any sighting to Agriculture Victoria.
  • South Australia: Not declared. Not declared under the Landscape South Australia Act 2019. Other laws may still apply.
  • Western Australia: Not listed. Not found in the Western Australian Organism List. Check with DPIRD before moving or keeping it.
  • Tasmania: Declared weed. Property managers are required by law to control declared weeds, and their import and sale are prohibited.
  • Northern Territory: Check NT list. There is no NT weed profile for it. Check the NT declared weeds list for its current status.
  • Australian Capital Territory: Declared pest, notifiable, prohibited. It is a declared pest throughout the ACT. You must report it to ACT Biosecurity. Dealing with it, such as selling, moving or keeping it, is prohibited.

Legal obligations

Every state and territory places a duty on landholders and people working on land to prevent the spread of invasive species, such as the general biosecurity obligation in Queensland and the general biosecurity duty in New South Wales. Declarations and control requirements differ between states and local government areas, so check the current official list before work starts.

  • New South Wales: Biosecurity Act 2015 (NSW), administered by NSW Department of Primary Industries and Regional Development
  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria
  • Tasmania: Biosecurity Act 2019 (Tas), administered by Biosecurity Tasmania

Sources