Quick Facts

Quick facts

• Original from the Americas, Pampas Grasses (Cortaderia selloana subspecies) is a large long-lived perennial tussock-forming grass to 4–6.5 m tall and nearly as wide, with a long fluffy flower head.
• It is an invasive coloniser of natural bush-land areas and pastures, mostly in moist areas.
• It was introduced to Australia as a garden plant, an ornamental, windbreak species and a source of fodder.
• Pampas Grass is still grown in some gardens as an ornamental plant, and can spread large distances from these sources of seed.
• Controlled mys manual, mechanical and foliar application of herbicides.

What Does It Look Like?

What is it?

Pampas Grass and Pink Pampas Grass (Cortaderia selloana and its sub-species; subsp. selloana & subsp. jubata) are huge, long-lived tussock-forming grasses to 6.5 metres tall and wide. Roots have been recorded up to 3.5 m deep, and plants have rhizomes, (crown) a type of underground stem that can re-sprouted if the top is removed or if part of the crown is detached from main clump can resprout. The large flowering spikes can protrude just beyond, with the top held above the mass of leaves; or are help on long stalks 1–2 m above or flower heads reaching a final height of up to 6.5 metres tall. Tussocks are dense, 1–4.5 metres tall. Drooping leaves are up to 2 metres long, with fine sharp serration (teeth), bluish-green above and dark green below, or bright green above and below. 

The Inflorescence or flower spikes are panicles, large, white to brownish or pinkish 'fluffy' plumes to 0.8–1 metre long, 20–25 cm wide, borne on erect stems. Each flower plume has up to 100,000 flowers. Individual spikelets in the flower-heads are about 2 mm long and 2–5-flowered. The flowering bracts (glumes) narrow to a short, 1–2mm long awn (bristle) inserted between 2 minute teeth. The female florets are silky hairy, but bisexual florets are hairless (Miles undated; Parsons & Cuthbertson 1992; Navie 2004).

Fruit (seeds) can produced on female or bi-sexual plants, that have normally self-fertilized or apomictic (reproducing without fertilization). 

Pampas Grass (Cortaderia selloana subsp. selloana, which is up to 6.5 m tall when in flower.

Pink Pampas Grass (Cortaderia elloana subsp. jubata) is up to 4.5 m tall when in flower.

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

Flower colour

White, Cream, Pink

Growth form (weed type/habit)

Grass

Where it currently grows? Preferred habitat

An escaped garden species, Pampas Grass grows in a wide variety of soils and climatic ranges, but prefers open sunny conditions with higher rainfall. Wet disturbed roadsides, railway lines, forested plantation sites, mangroves, riparian areas and swampy areas are particularly vulnerable to infestation.

Are there similar species?

Pampas Grass may be confused with a number of native species. The native Common Reed (Phragmites australis) also has seed in plumes, but these are carried at the tip of Bamboo-like leafy stems. P. australis occurs in swamps and along creeks.

Saw-sedges (Gahnia species) have similar very robust tussocks, but they have more open branched seed heads and shiny red or black seeds.

The introduced garden plant, Giant Reed (Arundo donax) also has a large plume-like seed head, but it, like Common Reed, is carried on a Bamboo-like leafy stem. It also sometimes escapes from cultivation in moist situations.

Why Is It A Weed?

What are its impacts?

Pampas 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, Pampas Grass was not included as one of the 20 WONS. However, it remains a weed of potential national significance. Pampas grass is an environmental weed that out-competes native vegetation and also grows in disturbed sites, waste areas, forestry plantations and along roadsides. Due to its large size and abundance of biomass, it is a fire hazard, that can also provides cover for pest animal species. 

Agriculture: Tufted clumps of Pampas and Pink Pampas Grass are of greatest potential weed significance to forestry operations, but are not considered agricultural weeds, because young plants are readily grazed by stock and have no potential to establish in cropping systems. Once established, pampas grass is highly competitive, restricting the replanting of pines (Government of South Australia 2021).

Native ecosystems: Pampas Grass has a number of invasive characteristics – rapid growth, large biomass accumulation, production of numerous seeds, and long distance seed dispersal (up to 30 kilometres). Once established, pampas grass is highly competitive, restricting the regeneration of native trees (Government of South Australia 2021), and can crowd out native plants, competing for light, water, nutrients and space (Parsons & Cuthbertson 1992). Dense stands of Pampas Grass restrict access by native fauna, humans and stock, and create fire hazards (Parsons & Cuthbertson 1992). It has the potential to invade large areas of urban bushland (Starr et al. 2003; Great Lakes Council 2006) and can invade and negatively impact wetlands, swamps and stream banks, bushland, open woodlands, grasslands, and coastal environments. (DPI NSW 20219).

How does it spread?

The flowers of both Pampas Grasses can produce over 100 000 seeds per plume, which are dispersed over long distances (up to 25 km) by wind or water. It can also spread by careless dumping of crowns of Pampas Grass plants into bushland. Plumes are often cut for dried flower arrangements, with the result that seed will be spread when they are discarded (Parsons & Cuthbertson 1992).

What is its history in Australia?

Cortaderia selloana was introduced to Australia an ornamental in the 1800s. It is grown as a garden plant, windbreak species and a source of fodder. Cortaderia jubata was introduced into Tasmania also as an ornamental relatively recently and is known to also occur in Victoria (Parsons & Cuthbertson 1992).

How To Manage It?

Best practice management

Pampas Grass and Pink Pampas Grass can be controlled by physical, mechanical, grazing and herbicides.   

Non-chemical control: Mechanical/manual removal of Pampas Grass is the best method of control where possible and should be carried out when the soil is moist, normally after rain. Remove plants when they are small. Make sure to remove all the crown and root system, which spreads out from the plants. Wear long sleeves and gloves as protection from the sharp leaves. Medium sized plants can be dug out taking care to remove all the crown roots and follow-up within 3 to 6 months or when regrowth is visible if following up with a chemical treatment. It is usually easier and safer to slash back the sharp leaves first. If plants are flowering, remove flower heads carefully, placing them in a sealed plastic bag for disposal to prevent further spread of the seed (Anon. undated; Parsons & Cuthbertson 1992). Large plants can be removed by machine. Seed heads should be removed first and placed in a plastic bag for disposal. Slash the plant and dig out the crown and roots. 

Grazing while pampas plants are young (stock avoid it once mature) is effective and follow up with another control method may be required. Grazing can prevent flowers from developing and setting seed. Only graze where the risk of causing new infestations is low.

Chemical control: A number of chemicals (herbicides) are available for the treatment of Pampas Grass as an alternative and useful follow-up to mechanical/manual methods. Foliar spray is the only practical application method.

Please see Invasive Species Unit, Biosecurity SA (2018); DPI NSW (2019); the Australian Pesticides and Veterinary Medicines Authority for chemical information http://www.apvma.gov.au

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Pampas Grass seeds germinate in spring. C. selloana subsp. selloana seedlings grow slowly at first; while C. selloana subsp. jubata seedlings develop rapidly. Both sub-species are sensitive to damage in the seedling stage. Most C. selloana subsp. jubata plants flower in the first year, and C. selloana subsp. selloana  plants may flower in their first year but the majority do not flower until the second or third year. C. selloana subsp. jubata flowers from January to mid-March whereas C. selloana begins flowering in March and continues until May (Parsons & Cuthbertson 1992).

C. jubata plants are all female and produce seeds apomictically (without pollination). The seeds are approaching maturity when the inflorescence emerges from its sheath in January (Parsons & Cuthbertson 1992).

Most cultivated plants of C. selloana on mainland Australia appear to be female clones which do not produce seed unless pollinated by a separate bisexual plant, possibly the reason why C. selloana subsp. selloana has not become widespread as a naturalised species. Where female and bisexual plants occur together the plant spreads more rapidly (Parsons & Cuthbertson 1992). 

Where Is It Found?

Which states and territories is it found?

ACT, NSW, QLD, SA TAS, VIC, WA

What areas within states and territories is it found?

Pampas Grass occurs in moist areas mostly around cities and towns, mainly in temperate parts  and in south-east Queensland and in some drier semi-arid areas, normally near waterways (AVH 2021). Cortaderia selloana subsp. jubata occurs mainly in Tasmania and Victoria, while Cortaderia selloana subsp. selloana is the most commonly occurring Cortaderia species throughout the rest of its weedy range in Australia. It is a problem weed in urban bushland, wet sclerophyll forest and pine plantations on the New South Wales central coast and also in the Mount Loft Ranges near Stirling, South Australia (Parsons & Cuthbertson 1992).

Where does it originate?

Cortaderia selloana subsp. jubata is native to the Andes Mountains of northern Argentina, Bolivia, Peru, and Ecuador, growing mainly at heights between 2800 and 3400 metres above sea level (Parsons & Cuthbertson 1992).

Cortaderia selloana subsp. selloana is native to Argentina, Bolivia Brazil, Chile, Paraguay, and Uruguay (POWO 2021; USDA 2021). It grows mainly on the lower altitude savanna and grassland plains (Parsons & Cuthbertson 1992).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

ACT, SA, TAS

Government weed strategies and lists – Weeds Australia

Is it on the National Alert List for Environmental Weeds?

NO

Government weed strategies and lists – Weeds Australia

Is it on the Agricultural Sleeper List?

NO

Government weed strategies and lists – Weeds Australia

Names And Taxonomy

Main scientific name

Cortaderia selloana 'subsp. selloana' & ‘subsp. jubata'

Other scientific names (synonyms)?

Does it have other known common name(s)?

Pampas Grass, Pink Pampas Grass, Cortaderia, Silvergrass