Canadian Food Inspection Agency
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Serrated Tussock - Nassella trichotoma
Figure 1: Tussock of serrated tussock
Serrated tussock is one of the worst invasive plants in Australia and is difficult to control. Mature plants can produce up to 140,000 seeds per year which can stay viable for many years in the soil.
The plant invades grasslands and competes with other species, reducing biodiversity. It is indigestible to livestock and thus decreases pasture productivity. It also contributes to increased fire risk.
Key Points:
- Not yet found in Canada.
- One of the worst perennial invasive plants in Australia.
- Infestations can result in loss of crops and livestock.
- Considered a fire hazard.
- A prohibited noxious weed in the Weed Seeds Order under the Seeds Act.
Where it's found
Serrated tussock has not yet been found in Canada.
Over the last century, since its initial introduction, it has gradually spread over millions of hectares of pasture in south-eastern Australia. Serrated tussock, native to South America, tends to grow along roadsides and in pastures.
What it looks like
Serrated tussock is a perennial grass with thin, bright-green, hairless leaves and long purplish, branched seed heads that weep toward the ground. Each plant can grow to a height of up to 70 centimetres. Its leaves are thin, tightly rolled (will roll smoothly like a needle between index finger and thumb), and have small, easily-felt serrations along their edges.
How it spreads
Serrated tussock has branched clusters of flowers (panicles) that break off from the parent plant and are easily carried by the wind for over 20 kilometres. As the panicles move, seeds are dropped. Seeds can also be transported in soil, by the muddy wheels of vehicles, in contaminated hay, in seed lots, and on animals and clothing. Seeds can remain dormant in soil for several years and germinate to form seedlings after the soil is disturbed. It is less likely to invade healthy, well managed grasslands.
Legislation
Serrated tussock is listed as a prohibited noxious weed in the Weed Seeds Order under the Seeds Act. Its presence in domestic and imported seed for planting is prohibited.
What we can do about it
There are steps you can take to help stop the spread of this weed in Canada:
- Use certified seed.
- Use clean grain, hay and straw; and,
- Look for serrated tussock in crops and in disturbed areas.
Reporting this invasive plant should be done through your local CFIA office. For a list of offices please call 1-800-442-2342 or visit the the CFIA website at: www.inspection.gc.ca.
Click on image for larger view
Figure 2 - Flower and seed heads
Figure 3 - Serrated tussock seeds
Figure 4 - Flower heads
Photo Credits
Figure 1: Tussock of serrated tussock
Photo Courtesy: Bill Strong. 2008
Figure 2: Flower seed heads
Photo Courtesy: Bill Strong, 2008
Figure 3: Serrated tussock seeds.
Photo Courtesy: USDA APHIS PPQ Archive, USDA APHIS PPQ, Bugwood.org
Figure 4: Flower heads
Photo Courtesy: Julia Scher, USDA APHIS PPQ, Bugwood.org
Invasive plants are plant species that spread when introduced outside of their natural past or present distribution and cause serious and often irreversible damage to Canada’s ecosystems, economy and society.
