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Pellitory (Parietaria judaica)

Pellitory is widespread around major urban areas in New South Wales, Victoria, South Australia, Queensland and Western Australia, and is particularly common in Sydney. Contact can cause severe skin reactions, while its pollen can cause asthma, conjunctivitis, rhinitis and hay fever.

Key facts

Type: Weed, herb.

Native to: Europe, western and central Asia, and northern Africa.

Established in: NSW, VIC, TAS, SA, WA.

Other names: Wall Pellitory, Asthma Weed, Pellitory-of-the-wall, Sticky Weed.

Best time to act: Look for new growth especially in autumn and spring, and treat plants while actively growing, preferably before flowering.

Identification

  • It is a many-branched perennial herb, usually 30–60 cm high but sometimes reaching 1 m.
  • Its greenish-brown or reddish stems have four evident ridges and are densely covered with irregularly curled hairs.
  • The glossy, prominently veined leaves are wedge-shaped, taper to a point, and are 2–8 cm long; both surfaces are hairy, especially along the veins.
  • Small greenish flowers grow in clusters in the leaf axils, and are mostly bisexual.
  • The fruit is a hard, irregular, dark brown to black, one-seeded structure about 1.2 by 0.8 mm.
  • Look-alike: It can be confused with the delicate annual native species Parietaria debilis and P. cardiostegia; pellitory has diamond-shaped leaves tapering to acute tips and flowers with the stigma on a long, thin stalk.
  • Look-alike: It also resembles the native shade nettle Australina pusilla, which occurs only in moist shady forests and is only slightly hairy.

Where it grows

In Australia it occurs mainly around major urban areas, on waste ground, in moist gullies, around sandstone outcrops, and in disturbed areas, including roadsides, gardens, rock crevices, walls and cracks in cement.

Why it matters

  • Contact with the plant can induce severe skin reactions.
  • Its pollen causes asthma, conjunctivitis, rhinitis and hay fever.
  • It competes strongly with other species and, in the Sydney area, can form dense stands that replace introduced ivy-leaved toadflax and native sickle fern.

How it spreads

  • Mature plants produce thousands of seeds each year, which are spread by wind and water.
  • The plant’s hairs stick to clothing and animals, helping transport flower heads and seeds; seeds also move in soil and mud attached to shoes, tyres and machinery.
  • Spread can also occur through contaminated garden soil, dumped garden waste, container-grown plants, recycled bricks and root pieces that develop into new plants.

Control options

  • Wear long clothing, a dust mask or half-face respirator, eye protection and protective gloves when handling the plant.
  • Hand-pull plants carefully, removing the entire root system, and place them in a plastic bag for disposal in the garbage.
  • Use registered herbicides on actively growing plants, preferably before flowering; herbicide may be needed where roots are firmly caught in cracks in stone walls or concrete.
  • Mulch bare soil, check clothing, tools and gloves for plant pieces, and follow up repeatedly to prevent regrowth.

Hygiene and washdown

  • Check shoes, tyres and machinery for attached soil or mud, which can carry seeds.
  • Check clothing, tools and gloves for plant pieces, and avoid moving contaminated garden soil or garden waste.
  • 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: Not a priority weed. Not a state or regional priority weed in NSW. The general biosecurity duty applies: anyone dealing with it must prevent, eliminate or minimise the risk it poses.
  • 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: Permitted, not declared. Listed as a permitted organism in WA, so it can be brought in, but it is not a declared pest.
  • Tasmania: Not declared. Not a declared weed in Tasmania. Other laws may still apply.
  • Northern Territory: Not declared. Not on the NT A to Z weed list, and Weeds Australia does not list it as declared in the NT. Check the NT declared weeds list before moving or planting it.
  • 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.

  • 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
  • South Australia: Landscape South Australia Act 2019 (SA), administered by the regional landscape board
  • Western Australia: Biosecurity and Agriculture Management Act 2007 (WA), administered by the WA Department of Primary Industries and Regional Development

Sources