Asthma weed, Parietaria judaica
Asthma weed, also known as pellitory of the wall and sticky weed, is a native of Europe, central and western Asia and northern Africa. It has invaded and is common in some part of eastern New South Wales, southern Victoria and south-eastern South Australia, as well as being present in other states and Lord Howe Island.
It can be found growing in urban areas (i.e. in walls, footpaths, embankments, etc.). It also inhabits gardens, rocky crevices, cliffs, coastal environs, riparian vegetation, waste areas and roadsides. In Helensburgh, it is present in damper areas, e.g. along creek and drainage lines, but is spreading.
As well as competing with our native species, it also has an impact on human health. Contact with the plant can induce severe skin reactions. Its pollen causes asthma, conjunctivitis, rhinitis and hay fever.
Pellitory has inconspicuous small flowers in spring and into summer. Plants mainly spread by abundant seeds, which are dispersed by wind, water and by attachment to humans and animals by sticky hairs.
Carefully remove by hand being sure to dig out all the roots. Where roots are anchored in walls or rocks, herbicide may need to be used. For large areas spraying with herbicide will be necessary.
For more information: https://weeds.dpi.nsw.gov.au/Weeds/Pellitory