Weeds of Australia - Fact Sheet

Top Scientific Name Family Common Names Origin Naturalised Distribution Notes

Scientific Name

Iris pseudacorus L.

Family

Iridaceae

Common Names

iris, pale yellow iris, paleyellow iris, water flag, yellow flag, yellow flag iris, yellow iris, yellow water iris

Origin

Native to northern Africa (i.e. Algeria and Morocco), the Madeira Islands, the Canary Islands, Europe and western Asia (i.e. Iran, Syria, Turkey, Azerbaijan and southern Russia).

Naturalised Distribution

Locally naturalised in southern Victoria and sparingly naturalised in south-eastern South Australia.

Naturalised overseas in New Zealand, most of the USA, Canada and southern South America (e.g. Argentina).

Notes

Yellow flag iris (Iris pseudacorus) is regarded as an environmental weed in Victoria and as a "sleeper weed" or potential environmental weed in other parts of southern Australia. It is widely cultivated as a garden ornamental and was first recorded as naturalised in Victoria in 1988. This species grows in shallow water and forms dense stands along waterways and in swamps. It thrives in temperate climates and can out-compete and replace native wetland plants.

In Victoria, yellow flag iris (Iris pseudacorus) has a relatively localised distribution, but grows in medium to large populations in these areas. It is mainly naturalised in riparian vegetation and permanent freshwater wetlands along the Yarra River in Melbourne. At some locations along the upper Yarra River, the understorey vegetation is dominated by yellow flag iris (Iris pseudacorus). It is particularly prevalent at the waterline of the main river channel and probably favoured by the comparatively stable water levels in this waterway.

This species may have the potential invade riparian vegetation and permanent freshwater wetlands over much of southern Australia. It appears on some local environmental weed lists in southern Victoria (e.g. in Banyule City and the The Shire of Yarra Ranges) and has been recorded in Yarra Bend Park in suburban Melbourne.

Yellow flag iris (Iris pseudacorus) is also an invasive aquatic plant in the USA, and is listed on the Global Invasive Species Database. Along the eastern seaboard, in the USA, it often invades open marsh areas and forms large colonies of almost impenetrable thickets.