Mitchell grass
Identifying the four species
David Phelps, Animal Sciences, and Jenny Milson, West Region, Longreach
The Mitchell grasses (Astrebla spp.)
Mitchell grasses are long lived grasses which grow in clay soils as tussocks of 5 cm to 50 cm in diameter. They were first recognised as a distinct grass genus with an individual botanical name (Astrebla, literally meaning 'straight awned') in 1876. The four individual species of Mitchell grass were recognised and named in 1928. Genus is the first word written in botanical names and always begins with a capital (eg Astrebla). It indicates that one group of grasses is different from another (eg Mitchell and Flinders grasses). Species is the second of the two Latin names written in botanical nomenclature and is always in lower case. It indicates that one grass within a genus is different from another within that genus (eg curly and bull Mitchell). Both botanical names are written in italics to recognise their Latin origins.
Hoop mitchell grass (Astrebla elymoides )
Hoop Mitchell - 50 cm tall with weeping seed heads*.
Hoop Mitchell is distributed throughout most of the Mitchell grasslands. It is often found in wetter, low lying areas as it is more flood tolerant than the other Mitchell grasses.
Hoop Mitchell grows to 50 cm tall. The leaves are hairless and do not curl as the plant hays off. The seed heads are long and narrow and hoop (or weep) towards the ground when mature; in dry years the seed heads may be too short to do so. The individual seeds are narrow (less than 4 mm) and lay hard against the seed head. It is the narrow weeping seed heads which distinguish hoop from the other Mitchell grasses.
Curly Mitchell grass (Astrebla lappacea )
Curly Mitchell - 50 cm tall with wavy backed seed heads.
Curly Mitchell is distributed throughout most of the Mitchell grasslands, although it is rarely found on the Barkly tablelands or central Australia. It is especially common in central Queensland.
Curly Mitchell grows to 50 cm tall. The leaves are mostly hairless and curl distinctly as the plant hays off. The seed heads may be long and curve over slightly, or may be short and straight depending on growing conditions. The individual seeds are wide (greater than 4 mm), bristly and loosely-arranged along the seed head in an alternate pattern. When viewed from behind, the shaft of the seed head appears wavy, helping to distinguish curly from the other Mitchell grasses.
Barley Mitchell grass (Astraleba pectinata )
Barley Mitchell - 80 cm tall with a barley-like seed head.
Barley Mitchell is distributed throughout most of the Mitchell grasslands. It is dominant in drier areas such as the Barkly tablelands and central Australia.
Barley Mitchell forms distinct tussocks and grows to 80 cm tall. The leaves have a sparse covering of long, thin hairs on the upper surface where the leaf joins the stem. These hairs help distinguish barley mitchell from the other Mitchell grasses. The seed heads are short and straight and held erect above the foliage. The individual seeds are wide (greater than 4 mm) and are packed tightly in two distinct rows against the straight seed head, like the ears of barley or wheat.
Bull Mitchell grass (Astrebla squarrosa).
Bull mitchell - 100 cm tall with hairy, prickly seeds.
Bull Mitchell rarely dominates the pasture, although it is especially common in flooded country, and low-lying moister areas. It is also prominent in the northern parts of the Barkly tablelands.
Bull Mitchell forms tussocks to 100 cm tall with coarse, unpalatable-looking stems and leaves. The large, bulky nature of bull Mitchell helps distinguish it from the other Mitchell grasses. The leaves are hairless with a distinct, whitish mid-vein on the upper surface. The large seed heads are short and straight and held on a long stalk which grows erect above the foliage, similar to barley Mitchell. The individual seeds are wide (greater than 4 mm) and prickly (because of hooks on the end of each awn) with long silky hairs at the base. The seeds pack tightly along the straight seed head.
In a nutshell
Curly and hoop are the shortest Mitchell grasses (50 cm). Curly Mitchell has upright seed heads, whilst hoop has long, narrow and weeping seed heads. Curly Mitchell also has distinctly curled leaves when dry.
Barley Mitchell is taller (80 cm), with upright seed heads that are packed in rows like barley or wheat. Unlike the other Mitchell grasses, barley has a sparse covering of long, thin hairs on the upper leaf surface where the leaf joins the stem.
Bull Mitchell is the tallest (100 cm), typically grows in flooded country and has much coarser, less palatable-looking, leaves and stems. The seed heads are tall and erect with large hairy and prickly seeds.
Further information
Copies of the following publications are available from your nearest DPI Client Information Centre or DPI Shop Online: Managing Mitchell Grass - A Grazier's Guide, by Ian Partridge. DPI 1996; Plant Identification in the Arid Zone, by Jenny Milson. DPI 1996; Pasture Plants of Southern Inland Queensland, by D.R.Henry et al. DPI 1995.
Other DPI Notes in this series include Mitchell grass - Australia's own grass, Mitchell grass - long term wool production and grazing pressure and Mitchell grass - safe burning, Mitchell grass - survival during drought and Mitchell grass - enhancing post-drought recovery.
For further information contact the DPI Business Information Centre on 13 25 23 (Queensland residents) or (07) 3404 6999 (non-Queensland residents) between 8 am and 6 pm weekdays, or e-mail callweb@dpi.qld.gov.au or visit the DPI&F web site www.dpi.qld.gov.au. This DPI&F Note is also published on the PrimeNotes CD-ROM.
* Illustrations taken from "Western Grasses" by Roberts, B.R. and Silcock, R.G. (1982). Darling Downs Institute Press. Maps taken from Jozwick, F.X. (1969). Some systematic aspects of mitchell grass. Australian Journal of Botany, Volume 17.
Information contained in this publication is provided as general advice only. For application to specific circumstances, professional advice should be sought. The Department of Primary Industries Queensland has taken all reasonable steps to ensure the information in this publication is accurate at the time of publication. Readers should ensure that they make appropriate inquiries to determine whether new information is available on the particular subject matter.
Created August 1997
Last updated 16 December 2005
