Perennial tussock forming C3 grass of up to 1m high. Flat leaves 1-5mm diameter, strongly ribbed on adaxial surface with rough margins. Infloresence an open panicle; stem seeds (cleistogenes) are also produced (Gardner, 1998).

Nassella neesiana was previously known as Stipa neesiana. It is difficult to distinguish from native Stipas.

Peak flowering of Chilean needle grass in Australia occurs between November and February (Gardner, 1998), however it has the ability to flower all year round (Ens, 2002). The seed bank has been estimated to potentially persist in the soil for up to 12 years even with annual glyphosate application (Bourdot and Hurrell 1992)!

Good stock feed during winter only

In Australia it invades disturbed grasslands and grassy woodlands of temperate regions with more than 500mm rainfall (Gardner, 1998)

Reproduces by sexual (chasmogamous) and asexual (cleistogamous) seed production. The cleistogenes are formed in the leaf sheaths and culms while the chasmogenes are found in the infloresence (Gardner, 1998). Up to 22,000 chasmogamous seeds/plant/year can be produced (Bourdot and Hurrell 1992). Production of the asexual seeds is a common response following slashing, grazing or fire (Gardner, 1998).

Nassella neesiana has the tendency to replace native flora (Agriculture and Resource Management Council of Australia and New Zealand et al., 2000; Ens, 2002), reduce ant abundance and alter the entire invertebrate community composition in conservation areas (Ens, 2002). Potential distribution overlaps an array of threatened species in Australia (Thorpe and Lynch, 2000). Agricultural productivity is thwarted by the replacement of palatable ground cover, injury to stock, reduction of produce quality and increased management costs (Thorpe and Lynch, 2000). Some sheep graziers in eastern Australia have been forced to switch to beef production (Thorpe and Lynch, 2000).

Preventative measures: A combination of chemical, mechanical, rehabilitation, competition, grazing management, biological control techniques and hygiene regimes are required to eradicate Chilean Needle Grass (Agriculture and Resource Management Council of Australia and New Zealand et al., 2000). As yet there is an absence of an effective herbicide (Agriculture and Resource Management Council of Australia and New Zealand et al. 2000).