Mexican feather grass (Nassella tenuissima)

If you see this plant contact your council weeds officer, the NSW Invasive Plants & Animals Enquiry Line 1800 680 244 or email



Mexican feather grass, is a potentially serious weed of pastures, native grasslands and woodlands. It is a highly adaptable grass that has the potential to infest up to 65% of New South Wales (NSW), causing major economic and environmental damage.

Mexican feather grass is unpalatable to stock, difficult to control and capable of growing in a variety of climates and soil types. It is able to tolerate prolonged periods of drought and can flourish in areas that are heavily grazed.

Mexican feather grass is closely related to serrated tussock (Nassella trichotoma), an invasive weed of temperate grasslands, and can only be distinguished when in flower. Mexican feather grass was initially found in some NSW nurseries, mislabelled and marketed as ‘elegant spear grass’, a name given to the native grass Austrostipa elegantissima.

During 2008, a wholesale nursery based in Victoria imported seed of ornamental stipoid grasses. It is believed that the seed was either mislabelled or contaminated with Mexican feather grass seed, which was then propagated, sold and distributed. The plants may have been sold under the names of Stipa lessingiana, S. capillata, S. capriccio or Stipa Regal Sensation.

Online overseas seed companies have also marketed the plant under various names including Stipa tenuissima, Stipa tenaccissima, elegant spear grass, white tussock, Texas tussock grass and ponytail grass.


Mexican feather grass reproduces by seed. From mid spring to summer it germinates freely on well-drained soils where there is little competition from other vegetation. Seeds can be dispersed by becoming attached to clothing, livestock and vehicles, or from contaminated seed and fodder.


Mexican feather grass is a dense, upright tussock up to 70 cm.

Leaves are 0.25–0.5 mm wide, up to 60 cm long and tightly rolled with overlapped edges. Leaves roll smoothly between the fingers like a needle, but feel coarse when sliding fingers downwards along the leaf blade. The ligule (a small, thin structure at the base of the leaf blade) is 0.5–2.5 mm long, opaque, papery and smooth.

Flowering stems are up to 70 cm high, round, smooth and hairless, with 2–3 unthickened nodes.
The flower head is 15–25 cm long and green or purplish in colour. An identifying feature of the plant is that the flower head does not detach from the plant and it has a leaf-like sheath that encloses its lower section.

Seeds are 2–3 mm long and encased by two purple or reddish-brown glumes, 6–10 mm long. Another distinguishing feature is the awn, which is 4.5–9 cm long and attached centrally to the end of the seed.


Written by Alan Maguire; prepared by Annette McCaffery and Annie Johnson; 2013 edition reviewed by Michael Michelmore; edited by Elissa van Oosterhout.


  • Csurhes S (2008) Mexican feather grass (Nassella tenuissima)—Pest plant risk assessment, Queensland Department of Primary Industries and Fisheries, Brisbane
  • Maguire A (2005) Mexican feather grass. NSW DPI Agfact P7.6.60
  • Victorian Department of Primary Industries (2004) Landcare Notes – Mexican feather grass: State prohibited weed, Frankston.

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Herbicide options

Contact your local council weeds officer for control advice for Mexican feather grass (Nassella tenuissima).

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Legal requirements

The content provided here is for information purposes only and is taken from the Noxious Weeds (Weed Control) Order 2014 published in the NSW Government Gazette, detailing weeds declared noxious in New South Wales, Australia, under the Noxious Weeds Act 1993. The Order lists the weed names, the control class and the control requirements for each species declared in a Local Control Authority area.

Area Class Legal requirements
All of NSW 1 State Prohibited Weed
The plant must be eradicated from the land and that land must be kept free of the plant

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Reviewed 2014

Mexican feather grass plant
Mexican feather grass plant (Photo: Alan Maguire)

Mexican feather grass as an ornamental grass
Mexican feather grass as an ornamental grass (Photo: Alan Maguire)

Mexican feather grass seedling
Mexican feather grass seedling (Photo: Alan Maguire)

Mexican feather grass showing the glumes
Mexican feather grass showing the glumes (Photo: Alan Maguire)

Nassella seeds
Nassella seeds (Photo: Alan Maguire)