Quick Facts

Quick facts

• Mission Grass (Cenchrus polystachios) is a large tussock-forming long-lived grass usually growing 2–3 m tall.
• It produces yellowish or brownish coloured seed-heads during late summer and autumn and dies back during the dry season.
• Mission Grass is a common weed of roadsides that also invades summer crops, pastures and native plant communities in the coastal districts of northern Australia.
• Once established, it has a competitive advantage over shorter-lived grasses and replaces native species, threatening the biodiversity of conservation areas.
• Because Mission Grass has a very high fuel load, it can significantly change the fire regime in invaded areas. This results in extremely hot fires that can cause the death of trees and transform natural savanna communities into exotic grasslands.

What Does It Look Like?

What is it?

Mission Grass (Cenchrus polystachios) is a tussock-forming long-lived grass usually growing 2–3 m tall. The flowering stems are upright, may be branched or unbranched, and sometimes root at the lower nodes. Several of these hairless stems arise from the base of the plant. The leaf blades are long and narrow (5–45 cm long and 3–18 mm wide) and are either hairless or somewhat hairy towards the base. Where the leaf sheath meets the leaf blade there is a fringe of hairs (a ligule) 1.5–2 mm long (Navie & Adkins 2007).

The long spike-like seed-heads are actually panicles with very short side branches. These seed-heads (3–35 cm long and 6–26 mm across) are held upright or are slightly drooping in nature. One or sometimes more of these seed-heads are borne at the top of the flowering stems. They are yellowish-green to brown in colour (mostly yellow) and consist of large numbers of densely packed, stalkless, flower spikelets.

Each of the flower spikelets (2–5 mm long) is surrounded by numerous feathery bristles (mostly 4–12 mm long). However, one of the bristles is significantly longer than the others (6–25 mm long). The seeds and seed-heads turn yellowish-brown or straw-coloured when mature. Each seed is 3–5 mm long and is shed from the seed-head with the bristles still surrounding it (Sharp & Simon 2002; Navie & Adkins 2007).

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

Flower colour

Yellow

Growth form (weed type/habit)

Grass

Where it currently grows? Preferred habitat

Mission Grass is a weed of roadsides, waste areas, disturbed sites, grasslands, open woodlands, forests, crops and pastures in tropical and sub-tropical regions (Navie & Adkins 2007).

Are there similar species?

Mission Grass is very similar to numerous other introduced grasses including African Feather Grass (Cenchrus macrourus) [as Pennisetum macrourum], Annual Mission Grass (Cenchrus pedicellatus) [as Pennisetum pedicellatum], Elephant Grass (Cenchrus purpureus) [as Pennisetum purpureum], Buffel Grass (Cenchrus ciliaris) [as Pennisetum ciliare] and South African Pigeon Grass (Setaria sphacelata) (Navie 2004).

Mission Grass can be distinguished from many, but not all, of these species by its yellowish or brownish seed-heads and its robust stature (i.e. often growing 2–3 m tall). It is most often confused with Annual Mission Grass, also known as Deenanth grass, which has purplish coloured seed-heads and is a shorter-lived plant.

Why Is It A Weed?

What are its impacts?

Mission 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, Mission Grass was not included as one of the 20 WoNS, nor was it included in a list of further WoNS in 2012 (Thorp & Wilson 1998–). However, it remains a weed of potential national significance.

Agriculture: Mission Grass is an important roadside weed in the coastal districts of northern Australia and is commonly seen as a dense monoculture on roadsides in the Northern Territory. It also invades cultivation, wastelands, pastures and conservation areas. In the Northern Territory it has been reported to reduce the yield of summer crops (e.g. sorghum, maize and cotton) and the viability of sown pastures (Parsons & Cuthbertson 2001; Miller 2006).

Native ecosystems: Mission Grass is a potentially significant environmental weed in northern Australia, where it is currently listed as a priority environmental weed in three Natural Resource Management regions. It is already having a significant impact in the northern parts of the Northern Territory and is actively managed by community groups in this region (Navie & Adkins 2007). Once established, Mission Grass has a competitive advantage over short-lived grasses and replaces native species, threatening natural biodiversity (Miller 2006).

The main impact this exotic grass has on native vegetation is the change it can have on the fire regime (Smith 2002). The above-ground parts dry off each year and, being very robust in nature, they create a very high fuel load (Douglas et al. 2004). This results in extremely hot fires late in the dry season which carry flames into the canopy of trees. These wildfires accelerate its invasion into native bushland and can result in the death of trees and the replacement of the natural savannas with exotic grasslands (Miller 2006; Navie & Adkins 2007).

Mission Grass invasions into savanna woodlands were shown to lead to a decrease in species richness and abundance of native species (Brooks et al. 2010). The invasion of Mission Grass and other exotic grasses in the Wildman and Mary River catchments, and in Kakadu National Park, is also known to be threatening the survival of some native animals. For example, it has caused a decline in the quality of the habitat available to the endangered Yellow-snouted Ground Gecko (Diplodactylus occultus), making its geographic distribution limited and its survival precarious (Navie & Adkins 2007).

How does it spread?

Mission Grass generally only reproduces by seed. These light and fluffy seeds are dispersed by water and wind, and may become attached to animals, clothing and vehicles. They may also be spread as a contaminant of agricultural produce (e.g., in hay and grain) (Parsons & Cuthbertson 2001; Navie & Adkins 2007).

What is its history in Australia?

Mission Grass has been widely cultivated as an ornamental throughout the tropical regions of the world, and this may have also been the case in northern Australia (Parsons & Cuthbertson 2001). However, it is known to have been one of several grasses introduced into Australia in the 1940s and 1950s for testing as pasture grasses. The first observations of it as a weed in the Northern Territory were in the Darwin area in 1970, where it was already well established, and the first herbarium collection was made in 1974. It has spread subsequently south to Katherine, east into Arnhem Land, southwest to the Daly River and north to the Tiwi Islands (Miller 2006).

How To Manage It?

Best practice management

Control programs should aim to restrict the spread of Mission Grass, prevent its entry to clean areas, reduce the fire hazard, and to reduce competition in crops and pastures. Small infestations can be hand-pulled or dug out with a hoe (Miller 2006). Check with your local council or state/territory government agency about its requirements for the control of Mission Grass. 

Non-chemical control: In cultivation, mature plants can be ploughed in prior to planting sown pastures or crops (Miller 2006), and a combination of cultivation and herbicide application usually gives the best results. In pastures, a combination of herbicide application and grazing management gives the best results (Parsons and Cuthbertson 2001). Slashing the plants before seed maturity will lessen the fire hazard and can be particularly useful along roadsides, as long as mature seeds are not present to be spread about by the machinery (Miller 2006).

Chemical control: Herbicides should be applied to Mission Grass that is actively growing prior to seeding, using spot sprays, rope wicks or boom sprays. Spot spraying is useful in newly infested areas or in areas of light infestation, while rope wicks and boom sprayers are more applicable to larger and denser infestations. Areas that have been recently slashed or burned provide an actively growing infestation with a reduced surface area, and this is the best situation for the application of herbicides (Miller 2006). However, fire should be used carefully as it can promote Mission Grass invasion if it is used at the wrong time of year (i.e. when fuel loads are very high).

See 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)

Mission Grass seeds usually germinate at the onset of the wet season in northern Australia (during October and November), though they may germinate at any time if adequate moisture is available. Flowering occurs mainly from late summer through to early winter, though some seed-heads may begin to appear with the first rains in spring. The main seeding period is from April to June and the aerial growth usually dies back during the dry season (Parsons & Cuthbertson 2001; Miller 2006).

Where Is It Found?

Which states and territories is it found?

NT, QLD

What areas within states and territories is it found?

Mission Grass is widely naturalised in northern and eastern Australia. It is most common in the northern parts of the Northern Territory and in northern Queensland. Also occasionally naturalised in central and south-eastern Queensland and in the southern parts of the Northern Territory (Navie & Adkins 2007).

Where does it originate?

Mission Grass is thought to be native to tropical and sub-tropical Africa (from Ethiopia and west tropical Africa south to Mozambique), and possibly also tropical Asia. It is now present throughout all the tropical regions of the world (i.e., it is pan-tropical) (Parsons & Cuthbertson 2001; GRIN 2007).

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

NT, WA

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

Cenchrus polystachios

Other scientific names (synonyms)?

• Cenchrus polystachios (L.) Morrone subsp. polystachios
• Panicum polystachion L.
• Pennisetum polystachion (L.) Schult.
• Pennisetum polystachion (L.) Schult. subsp. polystachion
• Pennisetum polystachyon A.D.Chapm. (incorrect spelling)
• Pennisetum polystachyum Schult. (incorrect spelling)

Does it have other known common name(s)?

Perennial Mission Grass, Missiongrass, Feathery Pennisetum, Feather Pennisetum, Thin Napier Grass, West Indian Pennisetum, Blue Buffel Grass