
Click on images to enlarge

infestation (Photo: Trevor James)

habit (Photo: Trevor James)

stem and leaf bases (Photo: Sheldon Navie)

close-up of tip of leaf blade (Photo: Trevor James)

upper leaves and seed-heads (Photo: Trevor James)

seed-head in flower (Photo: Trevor James)

close-up of flower spikelets (Photo: Trevor James)

young plant (Photo: Trevor James)
Scientific Name
Setaria parviflora (Poir.) Kerguelen
Synonyms
Cenchrus parviflorus Poir.
Panicum geniculatum Lam.
Setaria geniculata (Lam.) P. Beauv.
Setaria geniculata (Lam.) P. Beauv. var. geniculata
Setaria geniculata (Lam.) P. Beauv. var. pauciseta Desv.
Setaria gracilis Kunth
Setaria gracilis Kunth var. gracilis
Setaria gracilis Kunth var. pauciseta (Desv.) B. Simon
Family
Gramineae (South Australia)
Poaceae (Queensland, New South Wales, the ACT, Victoria, Tasmania, Western Australia and the Northern Territory)
Common Names
bent pigeon-grass, knotroot bristle grass, knotroot foxtail, marsh bristlegrass, pigeon grass, perennial foxtail, slender pigeon grass, slender pigeon-grass, slender pigeongrass, small-flowered pigeon grass, yellow bristle grass, yellow foxtail
Origin
Native to North America (i.e. the USA and Mexico), Central America (i.e. Belize, Costa Rica, El Salvador, Guatemala, Honduras, Nicaragua and Panama), the Caribbean and South America (i.e. French Guiana, Guyana, Surinam, Venezuela, Brazil, Bolivia, Colombia, Ecuador, Peru, Argentina, Chile, Paraguay and Uruguay).
Naturalised Distribution
Widely naturalised in southern and eastern Australia (i.e. in south-eastern Queensland, eastern and southern New South Wales, the ACT, Victoria, Tasmania, south-eastern South Australia and south-western Western Australia). It is also naturalised on Lord Howe Island.
Notes
Slender pigeon grass (Setaria parviflora) is sometimes regarded as an environmental weed in New South Wales and Victoria.