Cenchrus purpurascens (Swamp Foxtail)

Further reference:

https://keyserver.lucidcentral.org/weeds/data/media/Html/cenchrus_purpurascens.htm

Swamp foxtail (Cenchrus purpurascens) is a native plant which is of no concern localy when in the wild. But it can be come a problem weed when it is planted in gardens or used in landscaping, especially in moist habitats.

A quote from the above source:

"Swamp foxtail (Cenchrus purpurascens) is sometimes regarded as an environmental weed in Queensland and New South Wales. It is also regarded as an environmental weed in Victoria, and as a potential environmental weed in Tasmania and Western Australia. It has recently become popular as an ornamental grass that is often planted in gardens and amenity areas. As the common name suggests, swamp foxtail (Cenchrus purpurascens) generally invades moist sites such as river flats, swamps, marshes and low-lying pastures."

Regional distribution

Cenchrus purpurascens is listed in the following regions: