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King devil hawkweed (Pilosella piloselloides)

King devil hawkweed is a significant threat to alpine biodiversity in Australia, where it can form dense stands and outcompete native plants and pasture. It is present in Victoria but has not been found in NSW, and all species in the genus Pilosella are prohibited matter in NSW.

Key facts

Type: Weed, herb.

Native to: Europe and Asia.

Established in: VIC.

Best time to act: Look for flowers in summer; listed spray options specify application from October to May, but report the plant rather than attempting treatment yourself.

Identification

  • This perennial herb grows up to 75 cm tall, and broken stems or leaves release milky sap.
  • Leaves form a basal rosette and also grow along stolons, with sometimes 1–4 leaves low on the flower stem; they are bluish-green, stalkless, hairy, and 1.5–20 cm long by 0.5–3 cm wide.
  • Bright yellow, daisy-like flowers have square-ended petals, are 1–2 cm across, and grow in branched clusters of 3–35; flowering occurs in summer.
  • Flower stems grow up to 30 cm long and have short, stiff hairs; seeds are dark brown to purplish black, ribbed and tapered, about 2 mm long, with a short whitish pappus.
  • Look-alike: Mouse-ear hawkweed (Pilosella officinarum) is much shorter and has only one yellow flower per stem; wall hawkweed (Hieracium murorum) has leaves on stalks up to 4 cm long.
  • Look-alike: Dandelions (Taraxacum officinale) often have deeply divided leaves up to 35 cm long and one yellow flower per stem; flatweeds (Hypochaeris species) have one flowerhead per branched, hairless stem.

Where it grows

In Australia it is present in Victoria and has not been found in NSW; it is frost tolerant, favours cool climates with annual rainfall above 500 mm, and is most likely to sprout on disturbed sites with moist soils.

Why it matters

  • It forms dense stands with thousands of plants per square metre and is a significant threat to biodiversity in Australia's alpine regions.
  • It can outcompete native plants, especially alpine native grasses, and reduce food and habitat for native animals.
  • It competes with pastures and can reduce grazing productivity.

How it spreads

  • A stem can produce over 240 seeds; most germinate within a month on the soil surface, usually in summer, while some can remain viable in soil for up to five years.
  • Hairy seeds are carried by wind, usually an average of 2.6 m from the parent plant, though they may occasionally travel over 1 km; they can also spread by water and contaminated seed.
  • Seeds can be moved on boots, clothing and recreational equipment, attached to animals, or by vehicles, ski machinery and slashers.

Control options

  • Do not attempt to treat or dispose of this weed yourself; report any sighting in NSW immediately to the NSW Biosecurity Helpline on 1800 680 244.
  • NSW DPIRD, Agriculture and Biosecurity, will lead the initial response for treatment and disposal.
  • Contact your local council weeds officer for technical advice and identification assistance.

Hygiene and washdown

  • Check and clean boots, clothing, camping and recreational equipment, vehicles, ski machinery and slashers to avoid moving seeds.
  • Avoid moving contaminated seed or soil, and be aware that seeds can also spread by water and on animals.
  • 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): No national listing. Managed under state and territory law.
  • 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: Not declared. Not declared under the Catchment and Land Protection Act 1994. Other Victorian laws may still apply.
  • 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: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • 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: Not declared. Not declared under the Biosecurity Act 2023 (ACT). A general biosecurity duty still applies.

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.

  • Victoria: Catchment and Land Protection Act 1994 (Vic), administered by Agriculture Victoria

Sources