Quick Facts

Quick facts

• Originally from the warmer parts of Europe, Whorled Pigeon Grass (Setaria verticillata) is a loosely-tufted annual, that grows to 1m tall with flat green leaves, and cylindrical sticky flower/seed head.
• It is a weed of gardens, cultivated and disturbed land across all states and territories of Australia.
• Whorled Pigeon Grass is mainly dispersed by its seeds with their backwards facing barbed bristles, which readily adhere to clothing and the coats of animals.
• It can be controlled by cultivation and chemicals.

What Does It Look Like?

What is it?

Whorled Pigeon Grass (Setaria verticillata) is a loosely-tufted annual growing to 1m high. The stems are erect to bent abruptly like a knee-joint and erect plants often collapse during drying. The leaf blades are flat, 3–25 cm long and 3–12 mm wide, rough to the touch on both surfaces. Leaves have a leaf-sheath rolled around the stem where the blade meets the stem. The ligule a fringe of hairs about 1–2 mm long, 0.2–2 mm long, at the junction of the leaf blade and the leaf sheath meet on the stem. The ligule can be located by tracing a leaf down to where it joins the sheath and bending the leaf back at this point.

The Inflorescence or flower clusters (seed-head) is round and  spike-like, erect or nodding, dense, cylindrical a 3–12 cm long sometimes interrupted near base, branches to 10 mm long, or not. The spikelets (groups of flowers) are 1.7–2.4 mm long, most subtended by 1 bristles sometimes mores. The bristles are 3–15 mm long, more than twice as long as the spikelets covered with backwards-facing barbs. The bristles remain attached to the branches of the seed-head after the clusters break apart (Paterson 1992). Glumes (outer bracts) are small 1–3-nerved, with the lower (first) glume from one-third to one-half as long as spikelet; upper glume 5–7-nerved, sub-equal or equal to spikelet. Contained within the glumes is a lemma which becomes the husk of the seed.

The seeds are green about equal in length to the spikelet 1.7–2.4 mm long. 

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

Flower colour

Green

Growth form (weed type/habit)

Grass

Where it currently grows? Preferred habitat

Whorled Pigeon Grass is a weed of cultivated and disturbed land (Jacobs & Hastings 1993) and of irrigated areas (Lazarides 2002) waste land riparian areas and cultivation. Setaria species tolerate a broad range of environmental conditions and grow in moist or dry soils. They are common on roadsides, ditch banks, fields, pastures, cropland, orchards, vineyards and gardens (CDFA 2008).

Are there similar species?

Whorled Pigeon Grass can be distinguished from other Setaria species by the reflexed barbs on the bristles. The barbs in other species point forwards not backwards (Jessop et al. 2006; CDFA 2008).

Why Is It A Weed?

What are its impacts?

Where Whorled Pigeon Grass found growing it can form dense stands on roadsides and is a weed of crops, orchards, vineyards, pastures, lawns, waste areas and disturbed sites, but also invades coastal areas, open woodlands and riparian vegetation. Seeds of Whorled Pigeon Grass are well adapted to dispersal by animals because of the retrorse barbs on the bristles of the inflorescences. The fruiting panicle attaches itself to the fur of passing animals by means of the retrorsely-barbed bristles and thereby achieves wide distribution of the seeds.

Agriculture: Whorled Pigeon Grass is a potential seed contaminant (GRIN 2008) and a crop weed, especially of maize. As well as competing with a very wide range of tropical and temperate crops, it can cause difficulties during harvesting when the inflorescences become entangled with themselves and with the crop (CABI 2021). Not a problem in pastures as it is palatable.

Urban environments: It is also a nuisance weed of gardens, roadsides, footpaths and wasteland (Edgar & Connor 2000).

How does it spread?

Whorled Pigeon Grass is mainly dispersed by its seeds which, with their backwards facing barbed bristle, readily adhere to clothing and the coats of animals (Lazarides 2002). As with other Setaria species, seeds disperse with agricultural and other human activities, water, soil movement, animals and as crop seed and hay contaminants (CDFA 2008).

What is its history in Australia?

It is not known how or when Whorled Pigeon Grass arrived in Australia. It was first recorded in South Australia in 1904 (AVH 2021; Jessop et al. 2006).

How To Manage It?

Best practice management

Control as with any other grass depending on situation the plant or population is growing. 

Non-chemical control: plants can be hand-pulled and this method is employed by gardeners as Whorled Pigeon Grass is a common weed of gardens from cool temperate to tropical areas. Physical or mechanical control with other weeds where young plants are cultivated into the soils. Grazing is an effective way to control is grass as it is palatable to stock and other animals.

Chemical control: Herbicides can be used to control this grass in crops and on roadsides. 

Does it have a biological control agent?

NO

When does it grow? (lifecycle/growth calendar)

Whorled Pigeon Grass flowers in all months but especially in mid to late summer (Jessop et al. 2006).

Where Is It Found?

Which states and territories is it found?

Found in all Australian states and territories

What areas within states and territories is it found?

Whorled Pigeon Grass occurs in all states and territories of Australia (Jessop et al. 2006).

Where does it originate?

Whorled Pigeon Grass is a native of the warmer parts of Europe (Rominger 2007), and is now widely distributed across the world as a weed.

National And State Weed Listings

Is it a Weed of National Significance (WONS)?

NO

Where is it a declared weed?

Not declared in any states or territories. 

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

Setaria verticillata

Other scientific names (synonyms)?

• Panicum adhaerans Forssk.
• Panicum verticillatum L.
• Pennisetum verticillatum (L.) R.Br. ex F.Muell.
• Setaria adhaerens (Forssk.) Chiov.
• Setaria carnei Hitchc.

Does it have other known common name(s)?

Bristle Pigeon Grass, Burr Bristle Grass, Lovegrass, Rough Bristle Grass, Sticky Grass, Bristly Foxtail