Serrated Tussock

What is serrated tussock?

(Nassella trichotoma)
Serrated Tussock, image: Andrew CraneGeneric Weed Distribution Map
  • Serrated tussock is a perennial grass native to South America. It is a serious weed of pastures and native grasslands.
  • Serrated tussock is a declared weed under the Tasmanian Weed Management Act 1999. The importation, sale and distribution of serrated tussock are prohibited in Tasmania.
  • Serrated tussock is also a Weed of National Significance (WONS).


How to identify serrated tussock

  • Serrated tussock is a perennial (long-lived) tussock-forming grass with a deep root system. The leaves of serrated tussock feel rough (or serrated) if the finger and thumb are drawn down the blade. Flower stalks usually appear in spring, but may appear earlier in dry years and later in wetter years. A tussock in full flower presents a distinctly purple appearance due to the large number of purple florets.
  • Serrated tussock is similar to several of Tasmania's native tussock grasses, and is frequently overlooked until it begins to flower, at which time it is easily recognisable. The following characteristics enable serrated tussock to be distinguished from native tussock grasses:
  1. Leaf bases of serrated tussock are more tightly packed and more slender than those of other tussocks and are never purple or blue-green, but a whitish colour (see illustration).
  2. In summer when most other grasses have dried off to a straw-colour, the young serrated tussock plants still retain their bright green colour, except for the tips which are bleached.
  3. At the junction of leaf sheath and blade most grasses carry a small flap known as a 'ligule'. In the case of serrated tussock this is white, papery, rounded at the tip and never hairy (see illustration).
  4. The upward-pointing barbs on the leaf blade, which gives them their rough or serrated texture, are minute and almost invisible to the naked eye. If the leaves appear at all hairy, the plant is not serrated tussock (see illustration).
  5. The seed head breaks off whole. The previous year's seed heads do not generally remain on the plant.
  6. Flowering and seeding heads are a dark purple due to the colour of the two 'glumes' surrounding the seed (see illustration).
  7. Seed of serrated tussock is unlike the seed of any of the other tussock grasses with which it is likely to be confused (see illustration).
  8. For help in identifying serrated tussock, search the Dennis Morris Weeds and Endemic Flora Database for serrated tussock illustrations. If you are still in doubt about the weed you are dealing with, contact your Regional Weed Management Officer on 1300 368 550 for help.
Serrated Tussock, image: Andrew Crane
Image top: Serrated tussock, image: Andrew Crane
Image above: Serrated tussock infestation, image: Andrew Crane

Serrated tussock in Tasmania

  • Large, established populations of serrated tussock are located in the south east of Tasmania, particularly around Rokeby, South Arm, Sandford and Richmond. Other populations are known on the east coast at Swansea and Little Swanport, King Island and more recently recorded infestations are in the southern and northern Midland grazing areas (see map).
  • In Tasmania it is a significant weed of grazing land. The coarse leaves of serrated tussock are unpalatable, and dense infestations in pasture can completely smother all other desirable pasture species, rendering large areas incapable of supporting livestock.
  • Serrated tussock is of very low nutritional value to stock and if grazed, the leaves can form indigestible balls that can result in loss of condition and possible death.
  • Serrated tussock threatens the biodiversity values of Tasmania's native grasslands, displacing native species and often going undetected until infestations reach a large size. Serrated tussock will also invade other vegetation types such as grassy woodlands, and coastal communities.
  • A number of serrated tussock populations are found in the urban areas of Hobart. This may be a potential fire risk.


What is the legal status of serrated tussock in your area?

Detailed management and control guidelines for serrated tussock can be found in the Serrated Tussock Control Guide. Refer also to Herbicides for Serrated Tussock Control. For further information see DPIPWE's Weed Links and Resources.

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