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Graminae
Synonyms
Anthistiria ciliata Linn.; Themeda triandra Forsk.
Common names
Kangaroo grass (Australia).
Description
A perennial, forming leafy tussocks, with culms to 1-1.75 m.
Leaf- sheaths overlapping below, shorter than the internodes on the upper
parts of the culms. Panicle narrow, may or may not nod, brownish; fertile
spikelet, brown- hairy from the callus, the glumes brown to straw coloured,
shining, short pubescent; a geniculate, twisted awn, 3-5 cm long from the
fertile lemma (Henty, 1969). It is very similar to T. triandra.
Distribution
Australia, and throughout New Guinea.
Season of growth
Summer, starting growth in New South Wales in October- November,
i.e. south of 32°S, but growing most of the year in the tropics.
Altitude range
Near sea-level to 2 750 m.
Rainfall requirements
It grows over a wide rainfall range, about 450-1 250 mm.
Drought tolerance
Clumps survive long drought periods and produce rapid new growth.
Soil requirements
It grows over a wide range of soils. It does particularly well
on upland basaltic red earths and prairie soils, but is found on sands
and sandy loams.
Sowing methods
It is not usually sown as the seed is not very viable. Seed
heads, spread to allow stock to trample them in, may provide some new plants.
Seed does not readily pass through a drill, so it is broadcast. It can
be propagated by root division.
Response to defoliation
It will not stand heavy stocking and has disappeared from millions
of hectares of Australian pasture land. It is prominent in enclosed and
protected places such as railway lines. Defoliation during the growing
period reduces its root growth.
Grazing management
Graze lightly during the growing season and more heavily during
the dry season.
Response to fire
It survives fire very well.
Suitability for hay and
silage
It makes reasonably good hay.
Toxicity
No toxicity has been reported.
Main attributes
Its wide adaptability, tolerance to fire, and fair palatability.
Its frost tolerance and long grazing season (Hassall, 1976).
Main deficiencies
Its poor seed production.
Frost tolerance
It is tolerant of frost.
Latitudinal limits
South of 32°S it is a summer grass; further north it grows
year round.
Response to light
It grows very well in lightly shaded woodland.
Palatability
The softer types are very palatable and hence have mainly disappeared.
The coarser western forms are sparsely eaten.
Response to photoperiod
Various strains flower in short, medium and long days (Evans,
Wardlaw & Williams, 1964).
Chemical analysis and
digestibility
Green flowering material showed only 0.95 percent nitrogen,
0.32 percent calcium and 0.17 percent phosphorus (Allen, 1949). In winter
it is low in protein and digestible carbohydrates, and it is difficult
to breed sheep on grazing lands on which this grass is dominant (Moore,
1970).
Natural habitat
Grassland and open forest.
Tolerance to flooding
It is intolerant of flooding.
Genetics and reproduction
The basic chromosome number is x = 10. About 95 percent of
the population are tetraploids (2n=40), though diploid, triploid, tetraploid,
pentaploid and hexaploid plants have been found (Hayman, 1960). The diploid
plants are common in Tasmania and the central highlands of southern Australia.
The tetraploid plants are inland types. Most show both sexual and aposporous
behaviour (Evans & Knox, 1969).
Seed production and harvesting
T. australis seeds in November and forms few perfect seeds.
Many of the spikelets are male and barren, but there is usually one fertile
one in the cluster. The grain often fails to mature. The seeds do not germinate
readily. Hayman (1960) obtained best germination from domestic refrigeration
for 48 hours, then germinating on filter paper moistened with 0.1 percent
solution of potassium nitrate.
Economics
Grassland where T. australis is dominant gives useful pasture
after an initial burn, but under continuous grazing, productivity is likely
to decline, with the entry of small, prostrate grasses and miscellaneous
weeds (Henty, 1969). Conversely, the presence of almost pure stands of
T. australis indicates a light grazing pressure or no grazing, e.g. inside
fenced areas, along railway lines. Over 100 years' grazing, Themeda australis
grass climax grassland has been transformed into a Heteropogon contortus
subclimax; this change is non- reversible due to the loss of the Themeda
seed source. Very few seedlings occur.
Animal production
In northern Australia, Norman (1970) studied the growth of
beef shorthorn steers on a natural pasture dominated by Themeda australis,
Sorghum plumosum, Chrysopogon fallax and Sehima nervosum growing on a lateritic
red earth soil at Katherine. The average rainfall of 925 mm falls in the
four months from December to March. He further studied the effect of adding
Townsville stylo (Stylosanthes humilis) fertilized with 50-100 kg/ha superphosphate.
The native pasture was stocked at 4-12 ha per head and the mixed grass/legume
pasture at 1.2 ha per head. The steers on native pasture gained weight
for only six months of the year, from the start of the wet season until
one to two months after the rains ended. From late May to late November
they lost about 20 percent of their peak May weight. Steers on the grass/legume
pasture gained weight for about 45 weeks of the year. Over a six- to eight-week
period in October/November, from the time of the first early storms until
heavy rains have initiated the main flush of pasture growth, cattle on
all types of standing forage lost weight heavily.
Further reading
Norman, 1970.
Dormancy
T. australis has an after-ripening dormancy of six to ten months;
this time differs with ecotypes. It can be broken by gibberellic acid,
alternating temperatures, scarification or removal of glumes, or palea
and lemma (Groves, 1976).
Value for erosion control
It has been proved useful for stabilizing black soil gullies
at Surat, south-west Queensland.
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