Weeds of Australia - Fact Sheet

Top Scientific Name Synonyms Family Common Names Origin Naturalised Distribution Notes

Scientific Name

Cyperus congestus Vahl

Synonyms

Mariscus congestus (Vahl) C.B. Clarke

Family

Cyperaceae

Common Names

clustered flatsedge, dense flat sedge, dense flat-sedge, dense flatsedge

Origin

Native to southern Africa (i.e. Lesotho, Namibia and South Africa).

Naturalised Distribution

This species is widely naturalised in the wetter regions of southern Australia (i.e. in eastern New South Wales, southern and eastern Victoria, Tasmania, south-eastern South Australia and south-western Western Australia).

It is possibly also naturalised in Brisbane in south-eastern Queensland, and is naturalised overseas in New Zealand and Hawaii.

Notes

This species, like many other sedges, is commonly a weed of roadsides, disturbed sites and damp ground. It also invades wetlands and waterways, and is regarded as an environmental weed in parts of Western Australia, Victoria, South Australia and New South Wales. It is regarded as an aquatic and wetland weed in Western Australia and listed as a moderately invasive species in WeedBase (i.e. a database of the environmental weeds of Western Australia).

Dense flat-sedge (Cyperus congestus) is also listed as an environmental weed in the wider Sydney and Blue Mountains region and in the Goulburn Broken Catchment in Victoria. In South Australia it has been recorded in the Onkaparinga River Recreation Park and is listed as a priority weed in the Pine Gully Reserve, near Adelaide.