Quick Facts

Quick facts

  • Giant Parramatta Grass (Sporobolus fertilis) is long-lived grass usually growing 70–160 cm tall, but occasionally reaching up to 2 m in height. It forms large tussocks up to 40 cm across.
  • It is a vigorous, persistent and invasive grass that is well adapted to a wide range of climatic conditions.
  • Giant Parramatta Grass is a particularly serious problem in pastures in the wetter areas on the north coast of New South Wales, but has the potential to invade much of eastern Australia.
  • It is of low palatability and significantly reduces the productivity and carrying capacity of pastures.
  • Giant Parramatta Grass also invades native grasslands, open woodlands, conservation reserves and wetlands. It replaces native plants in these habitats and can eventually change the community structure of, and threaten the biodiversity of, native grasslands and rangelands.

What Does It Look Like?

What is it?

Giant Parramatta Grass (Sporobolus fertilis) is an upright and long-lived grass usually growing 70–160 cm tall, but occasionally reaching up to 2 m in height. It forms large tussocks up to 40 cm across. The hairless flowering stems are relatively slender, but somewhat wiry, and are usually not branched. Its leaves are very narrow with a leaf sheath, which partially encloses the stem, and a spreading leaf blade that may droop towards the ground. The leaf sheaths are hairless, or have some tiny hairs along their margins, and may become separated from the stem as they age. The leaf blades (14–110 cm long and 1.5–5 mm wide) are hairless, may be flat or somewhat rolled inwards, and have pointed tips. Where the leaf sheath meets the leaf blade there is a fringe of tiny hairs (a ligule) about 0.2–0.5 mm long (Simon & Jacobs 1999; Navie & Adkins 2007).

The seed-heads are borne at the top of the stems and are very thin and spike-like in appearance (15–50 cm long and 0.5–2 cm wide). These seed-heads have several relatively long branches (2–8 cm long) that are held closely to the stem. However, some of the lowest branches may droop away slightly from the central stalk of the seed-head.

Each of the seed-head branches bears numerous tiny, densely packed, flower spikelets almost to its base. These dark green or greyish-green flower spikelets (1.5–2 mm long) contain a single tiny flower inside a pair of bracts (known as glumes). The lower glume is 0.4–0.7 mm long and the upper glume is 0.8–1.3 mm long (i.e., at least half the length of the flower spikelet). The tiny seeds turn yellowish-brown or reddish-brown as they mature. These seeds (0.8–1.2 mm long and 0.5–0.75 mm wide) separate from the remainder of the flower spikelet at maturity, leaving behind the pale coloured floral bracts on the seed-head (Simon & Jacobs 1999; Navie & Adkins 2007).

For further information and assistance with identification of Giant Parramatta Grass contact the herbarium in your state or territory.

Flower colour


Growth form (weed type/habit)


Where it currently grows? Preferred habitat

Giant Parramatta Grass is a weed of pastures, roadsides, disturbed sites, waste areas, open woodlands, grasslands and wetlands in the tropical, sub-tropical and warmer temperate regions of Australia (Navie & Adkins 2007).

Are there similar species?

Giant Parramatta Grass is very similar to other introduced grasses including Parramatta Grass (Sporobolus africanus), the Giant Rat's Tail grasses (S. pyramidalis and S. natalensis) and American Rat's Tail Grass (S. jacquemontii). It is also very similar to some of the Native Rat's Tail grasses, particularly the widespread and common slender rat's tail grasses (S. creber and S. elongatus). Distinguishing between these species is often very difficult and a specialist may need to be consulted.

Giant Parramatta Grass is a relatively large plant (usually 80–160 cm tall) with relatively large spike-like seed-heads. These seed-heads have numerous branches (20–80 mm long) that are held close to the main stem. Parramatta Grass is very similar, but is smaller in stature (usually less than 50 cm tall) and its spike-like seed-heads have shorter branches (only 10–20 mm long). The Giant Rat's Tail grasses are similar in stature to Giant Parramatta Grass, but their seed-heads have branches that spread away from the main stem when fully open. American Rat's Tail grass is a smaller plant (usually 50–75 cm tall) and its seed-heads also have branches that spread away from the main stem when fully open (Simon & Jacobs 1999; Navie 2004).

The Slender Rat's Tail grasses are moderately-sized plants (usually 50–100 cm tall) and are distinguished by their very slender spike-like seed-heads. These seed-heads have short to long branches (5–80 mm long) that are always held closely to the main stem and are often widely spaced near the base of the seed-head (Simon & Jacobs 1999; Navie 2004).

Why Is It A Weed?

What are its impacts?

Giant Parramatta Grass was included in the list of 71 species that were nominated by state and territory governments for assessment as Weeds of National Significance (WONS). Following an assessment process, Giant Parrametta Grass was not included as one of the 20 WONS. However, it remains a weed of potential national significance.Giant Parramatta Grass is a vigorous, persistent and invasive grass that is well adapted to a wide range of climatic conditions.

Agriculture: It is a particularly serious problem in pastures in the wetter areas on the north coast of New South Wales. It is of low palatability and reduces the productivity of agricultural land by completely displacing desirable pasture species. The productivity and carrying capacity of invaded pastures can be significantly reduced, and farmers have reported losses in carrying capacity ranging from 10–80% depending on the density of the infestation. Cattle grazing in pastures infested with Giant Parramatta Grass also take significantly longer to reach equivalent weights to those grazing in uninfested pastures and the tough, fibrous nature of the stems can also increase teeth wear in livestock (Walton 2001; Navie & Adkins 2007).

The economic costs incurred in managing this species are also quite high and heavily infested areas have reduced land values. Giant Parramatta Grass can have other less obvious impacts, such as causing damage to asphalt on roadsides and tracks and decreasing the aesthetic appeal of infested areas. Large infestations may also affect fire intensity and/or frequency, particularly in winter and spring (Walton 2001).

Native ecosystems: Giant Parramatta Grass is also regarded as a significant environmental weed in New South Wales and Queensland. It invades native grasslands, open woodlands, conservation reserves and wetland areas and when fully established it excludes native plants. Giant Parramatta Grass is one of the exotic perennial grass species invading native plant communities in New South Wales that have been listed as a "key threatening process" (Navie & Adkins 2007). It is also ranked among the top 50 environmental weeds in south-eastern Queensland (Batianoff & Butler 2002) and is thought to pose a significant threat to rangeland biodiversity in central and northern Queensland.

How does it spread?

Giant Parramatta Grass produces large quantities of tiny seeds, which become somewhat sticky when wet. These seeds may become attached to animals and vehicles and can also pass through animals intact. They are also dispersed by water, in mud and in contaminated agricultural produce (Navie & Adkins 2007). Giant Parramatta Grass seeds are regular contaminants of pasture grass seed lots.

What is its history in Australia?

Giant Parramatta Grass was introduced accidentally into Australia, although it has been documented as being native to Australia in the past (Simon & Jacobs 1999). It was first recorded as being present in Australia in 1886 (in Brisbane and Sydney) and had appeared at Nana Glen in northern New South Wales by the 1920s. It has spread greatly from these early records and now infests a total of 250 000 hectares in New South Wales (Walton 2001).

How To Manage It?

Best practice management

Non-chemical control: Maintaining pastures in good condition reduces the chance of invasion and increases competition against Giant Parramatta Grass. Heavy grazing will not control Giant Parramatta Grass and may actually favour its spread, so an appropriate grazing regime is important in any management strategy. Good hygiene and quarantine are also important to prevent the spread of seeds to uninfested areas. Moving stock from infested areas into clean areas is not recommended, unless they are spelled for at least five days in holding yards (Land Protection 2006).

Small infestations or isolated plants can be dug out or spot-sprayed with herbicide. Cut any seed-heads off and put them in a bag for destruction before digging out or spraying the plants in order to prevent spreading the seed. After removing Giant Parramatta Grass plants, the runners or seeds of useful grasses should be planted in the divot to provide competition with any Giant Parramatta Grass seedlings (Betts & Officer 2001).

With larger or heavier infestations it needs to be decided whether to keep the existing pasture and manage the Giant Parramatta Grass to reduce its effects, or to remove the existing pasture and replace it with more competitive and productive species. Replacing the existing pasture by cultivating the soil and planting an appropriate sown pasture or crop is a more intensive approach and is usually only practical in better quality country (Betts & Officer 2001).

Where the existing pasture is to be kept, it should be managed is such a way to encourage a strong, competitive pasture understorey to replace the Giant Parramatta Grass. This management strategy should involve appropriate levels of grazing, the selective application of herbicides, and possibly also slashing or burning to precondition the stand. Slashing when Giant Parramatta Grass is in seed can rapidly spread the seed, and is only recommended where the grass is already dominant in a pasture.

Chemical control: The use of a pressurised wick wiper to selectively apply herbicide to Giant Parramatta Grass is probably the most useful tool in managing this species. It can be used to apply herbicides at a low rate to reduce seeding and improve grazing quality and is often cheaper and more effective than slashing (Betts & Officer 2001).

To get the most effective results with a pressurised wick wiper, a package of three treatments should be applied over an 18 month period. The first treatment should be applied in mid summer, when the Giant Parramatta Grass is actively growing. Make sure there is a significant height difference between the Giant Parramatta Grass and other pasture plants by allowing livestock to selectively graze down the good pasture plants. A second treatment should be applied in late summer or early autumn to prevent seeding, and a follow-up treatment should be applied the next summer (Land Protection 2006).

Check with your local council or state/territory government agency about its requirements for the control of Giant Parramatta Grass.

Also see the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au

Does it have a biological control agent?


When does it grow? (lifecycle/growth calendar)

Giant Parramatta Grass seedlings mainly emerge in spring or early summer, depending on rainfall, but some may emerge throughout the year if soil moisture is adequate. Plants mainly flower in mid to late summer in temperate areas, but may flower year round depending on moisture availability in tropical regions. The majority of seed are set during late summer, though seeds can also be present year round. Seed viability is very high and the seeds can remain viable in the soil for many years (Walton 2001).

Where Is It Found?

Which states and territories is it found?


What areas within states and territories is it found?

Giant Parramatta Grass is widely naturalised in the eastern parts of Australia and is most common in the coastal regions of New South Wales and Queensland. It is occasionally also naturalised in the ACT, Victoria, and the inland parts of New South Wales and Queensland. It is also present on Christmas Island and the Cocos Islands, though it may be native to these offshore islands (Navie & Adkins 2007).

In New South Wales the heaviest infestations presently occur in the mid north coast region, between the Grafton and Kempsey districts. However, it is rapidly spreading north and south along the coast. Isolated infestations also occur around Dubbo, Cowra and Hay. In Queensland the largest infestations are found in the Mackay and Proserpine districts, in coastal central Queensland (Walton 2001).

Where does it originate?

Giant Parramatta Grass is native to the Indian sub-continent (India and Sri Lanka), eastern and south-eastern Asia (China, Japan, Korea, Taiwan, Myanmar, Indonesia, Malaysia, the Philippines and Papua New Guinea) and some islands in the western Pacific (GRIN 2007).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?


Where is it a declared weed?


Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?


Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?


Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Sporobolus fertilis

Other scientific names (synonyms)?

  • Agrostis fertilis Steud.
  • Sporobolus diandrus var. major Buse
  • Sporobolus indicus var. fertilis (Steud.) Jovet & Guedes
  • Sporobolus indicus var. major (Buse) Baaijens


Does it have other known common name(s)?

Rat-tail Grass, Smutgrass, Australian Smutgrass, Bloomsbury Grass

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