Quick Facts

Quick facts

• Pellitory (Parietaria judaica) is a many-branched perennial herb that grows to 60 cm high, with stems and leaves covered with irregularly curled hairs.
• It is found in New South Wales, Victoria, South Australia, Queensland and Western Australia around the major urban areas and is particularly widespread in Sydney.
• Pellitory is common on waste ground, in moist gullies, on sandstone outcrops, and as a groundcover. It is also found growing out of rock crevices, walls and cracks in cement.
• Contact with the plant can induce severe skin reactions. Its pollen causes asthma, conjunctivitis, rhinitis and hay fever.
• Control involves hand-pulling and the use of herbicides, and should be carried out with care.

What Does It Look Like?

What is it?

Pellitory (Parietaria judaica) is a many-branched perennial herb that usually grows 30-60 cm high and sometimes up to 1 m. Stems are greenish brown or reddish, 4-angled (having 4 evident ridges) and densely covered in irregularly curled hairs. Leaves are glossy, wedge-shaped and tapering to a point at the apex, 2-8 cm long, prominently veined, hairy on both surfaces especially along the veins, with a leaf stalk 5-20 mm long.

Flowers are small, greenish, in clusters in the leaf axils (the angle between leaf and stalk), mostly bisexual but some are unisexual.

The fruit is 1-seeded, irregular, hard, dark brown to black, 1.2 by 0.8 mm in size and enclosed by the remains of the flower. The rootstock is woody with fibrous lateral roots (Harden 2000; Blood 2001; Parsons & Cuthbertson 2001).

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

Flower colour

Green

Growth form (weed type/habit)

Herb

Where it currently grows? Preferred habitat

Pellitory is common on waste ground, in moist gullies, in and around sandstone outcrops, and as a groundcover in disturbed areas. It is also found growing out of rock crevices, walls and cracks in cement. It is a common weed on roadsides and in gardens, especially where there is water seepage (Sydney Central Regional Weeds Committee 2003; Thorp & Wilson 1998-). It tolerates drought, sun, shade, frost and desiccation (Blood 2001).

Are there similar species?

Parietaria judaica is commonly confused with the more delicate annual native species, P. debilis and P. cardiostegia, but differs in having leaf blades tapering to acute tips, being diamond-shaped rather than egg-shaped, and having flowers with the stigma (the part that receives the pollen) on top of a long thin stalk rather than being almost stalkless (Harden 2000; Spooner et al. 2007).

It also looks similar to the native shade nettle Australina pusilla which is found only in moist shady forests and is only slightly hairy (Harden 2000; Blood 2001).

Why Is It A Weed?

What are its impacts?

Human impacts: The main impact of Pellitory is on human health. Contact with the plant can induce severe skin reactions. Its pollen causes asthma, conjunctivitis, rhinitis and hay fever (Sydney Weeds Committees undated A). It also competes strongly with other species.

Native ecosystems: In the Sydney area it replaces the introduced ivy-leaved toadflax Cymbalaria muralis, and the native sickle fern Pellea falcata, resulting in dense, single species Pellitory stands (Parsons & Cuthbertson 2001).

How does it spread?

Every year, mature Pellitory plants produce thousands of seeds which are spread by both wind and water. The hairs covering the plant also stick to clothing and animals, allowing the flower heads to be transported and facilitating further spread of the seeds (Sydney Central Regional Weeds Committee 2003). Seeds are also spread in soil and mud attached to shoes, tyres and machinery (Sydney Weeds Committees undated A). Pellitory can be spread by the movement of contaminated garden soil and from dumped garden waste (Blood 2001). Pellitory is a common contaminant of container-grown plants and is often spread via recycled bricks (Blood 2001). There is some local spread from pieces of root that develop into whole new plants (Thorp & Wilson 1998-).

What is its history in Australia?

Pellitory has the dubious honour of being reported as one of the first introduced weeds in Australia. Although entry into Australia is not clear, it has been suggested that it was initially introduced at Woolloomooloo, Sydney, during the early 19th century on marble used for head stones in cemeteries (Sydney Central Regional Weeds Committee 2003).

How To Manage It?

Best practice management

Pellitory is a serious noxious weed in the Sydney Metropolitan region. A project has commenced in some council areas to develop and distribute educational material and incentives kits to help residents identify and remove this weed from their gardens. A free Asthma Weed Removal Kit and guide are available from the Randwick Council (Sydney Weeds Committees undated B). It is recommended that long clothing, a dust mask or half face respirator, eye protection and protective gloves be worn when handling this weed (Sydney Weeds Committees undated A).

Non-chemical control: Physical control: Control involves hand-pulling plants, taking care to remove the entire root system to prevent reshooting. Plants should be placed in a plastic bag and put in the garbage. Clothing, tools and gloves should be checked for pieces of the plant, to prevent further spread. Bare soils should be mulched to reduce regrowth. Repeated follow up treatment is needed to eradicate this weed. If roots are firmly caught in cracks in stone walls or concrete, herbicide may be required.

Chemical control: Herbicide should be applied to the plants while actively growing, and prior to flowering if possible (Sydney Weeds Committees undated A). Before commencing any chemical control program, contact your local council's weeds officer or see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au 

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Germination of Pellitory can occur at any time of the year but mainly occurs in autumn and spring. Plants that germinate in autumn grow at a moderate rate during winter, and flowering starts in spring, continues through summer, and in warmer areas, into winter. Plants that germinate in spring and summer may not flower in the first year. In established plants, flowering may be continuous throughout the year with new growth appearing in autumn and spring (Parsons & Cuthbertson 2001).

Plants grow and produce seed very rapidly, within 2-3 weeks under favorable conditions. Regrowth is persistent, and plants can flower and set seed most of the year (Sydney Weeds Committees undated A). Fresh disturbance seems to stimulate mass germination and it is not uncommon to see solid carpets of Pellitory on building sites (Blood 2001).

Where Is It Found?

Which states and territories is it found?

NSW, QLD, SA, VIC, WA

What areas within states and territories is it found?

Pellitory is present in New South Wales, Victoria, South Australia, Queensland and Western Australia, mainly in and around the major urban areas. In Sydney, New South Wales, the weed is widespread over the Inner Sydney region, continuing to spread through the North Shore, the Western Suburbs to Mount Druitt and to Sutherland in the south. In Sydney, P. judaica is commonly known as Asthma Weed (Sydney Central Regional Weeds Committee 2003). In Western Australia it is naturalised at Fremantle on wasteland and old walls, and also on cliffs, such as along the Swan River (Hussey et al. 1997). It is also found in south-east South Australia and south-east Queensland (AVH 2008).

Where does it originate?

Pellitory is native to Europe, western and central Asia and northern Africa (Thorp & Wilson 1998-).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NSW, WA

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

Parietaria judaica

Other scientific names (synonyms)?

Parietaria diffusa Mert. & Koch (misapplied by Beadle, N.C.W., Evans, O.D. & Carolin, R.C. 1962, Handbook of the Vascular Plants of the Sydney District and Blue Mountains. 302.; Willis, J.H. 1973, A Handbook to Plants in Victoria Edn 2. 2: 31.)

Does it have other known common name(s)?

Wall Pellitory, Asthma Weed, Pellitory-of-the-wall, Sticky Weed, Kirribilli Curse, Dead Nettle