There are some plants that the Australian gardener should grow and The Golden Wattle (Acacia pycnantha), the Australia's National Flower and Kangaroo Grass (Themeda triandra syn T. australis) is at the very top of that list.

Kangaroo grass (Themeda triandra) often develop a range of attractive leaf colours from blue, grey, red, purple throughout the year and are spectacular when the plants raise the seed heads above garden.

In 1984 when my family first moved to our Cuumbuen country bush block, Kangaroo Grass (Themeda triandra) was to be found growing in small colonies through out the area, but the prolonged periods dries since 1984 has caused many of these colonies to retreat to fewer plants and sites. The Kangaroo grass (Themeda triandra) is one of a number of native grasses suitable for the home gardener.

On one of my numerous field trips through Cuumbuen Country, I found a lonesome (Barbed Wire Grass) Cymbopogon refractus grass plant.  Barbed Wire Grass is a native relative of  the exotic Lemon Grass and is also a C4 grass. The successful germination of a few seeds from that plant spawned a number  of plants that grew and reseeded in a cultivated garden bed.

In recent times even the Cymbopogon refractus has shown that it too is struggling to cope with the dry winters and the prolonged drought.

Kangaroo Grass is a C4 grass and has a unique Calvin-Benson Cycle that allows the leaves to 'recycle' CO2 gas. The C capability to double cycle CO2 was thought by experts (see online article below) to give it an ecological advantage over other grass types. Vast areas of the plains of southern Africa are covered in Themeda australis, a morphological dead ringer for T. triandra.

C4 grasses were thought to be important in fixing CO2 and it was believed that T. triandra had great potential in controlling increases in green house gases. It was believed that Calvin-Benson Cycle of C4 grasses made them better plant competitors over other types of grasses.

Kangaroo Grass grows in small clumps or tussocks that are easily divided into individual plants and potted-on in the late winter. On division of the tussock ensure you cut-back the leaf area but never below the apical bud or growth tip. 

Propagation of Kangaroo grass (Themeda triandra) by seed is reputedly difficult. The propagation of the grass from seed needs to be carefully managed in order to ensure germination and good germination rates.

Collecting Seed. The seed flower head of Kangaroo grass (Themeda triandra) is a complex inflorescence and the collection of seed in summer requires some skill and propitious timing. The grass does not shed all its seeds readily, instead each seed on each plant will ripen over the summer to early autumn making harvesting difficult to strip by machinery.

The seed is a dark brown to black spear like seed with an awn giving  the seed the appearance of a hunting spear.  Colour and feel are the best guides to selecting viable seed. The seed head must be swollen, dark and dry hard to touch and the awn must be black with a dry stiff unyielding feel.

If the seed comes away easily from the flower then you can be assured that the potential for viability and germination will be increased. The very tip of the seed must be dry and sharp to the bare skin.

The fertile lemma is linear stipe-like, firm passing into the awn, bi-sexual and without a palea. The awn is 4-6cm long, geniculate about the middle, the awn column is pubescent (covered with fine soft short hairs) and the bristle scabrous (having or covered with scales or small projections and rough to the touch).

The awn can be removed from the seed. This should be done otherwise after a day the humid awns will twist and mat and the separation of the seed from awn will be more difficult.  The twisting or screwing of the awn is the evolutionary method that awned grasses employ to sow the seed head in to the soil.

Seed viability is not a major concern, but seed viability percentages begs some further research.  Word of mouth has it that good Themeda triandra seed is better easily germinated if sown within a year of collection, however I have had some success with well stored seed more than 15years old.

Sowing the seed

In nature, by natural seed dispersal, Kangaroo grass (Themeda triandra) will be sown from December to May. In the nursery or the home garden, seed can be sown in mid spring (September - March) in free draining, fertiliser neutral seed raising mix such as vermiculite and perlite (1:3), or coarse washed river sand and cocopeat (1:3).  Seeds should be planted 'spear-head' into the mix, ensuring to cover the seeds. The viable seeds will quickly germinate and can be pricked out into pots into a native premium seed potting mix (eg Martins) and coarse washed river sand (3:1). When using Australian Standards Premium Potting mixes a soluble fertiliser need not be added until 5 to 6 weeks after sowing and only from autumn to spring. For other potting mixes the propagator should compare the potting mix contents with Australian Standards Premium Potting mixes.

If sowing the seed with the awn, the awn will absorb moisture from the air or otherwise and naturally twist or screw the seed into the soil.  This intriguing phenomenon can be observed in real time.

When planting Kangaroo grass (Themeda triandra) into the garden or a regeneration area the seedlings will need to be protected from all herbivores (eg Possums, Kangaroos, Feral and Domestic animals). I try not to plant C4 grasses near C3 grasses. It is my observation that C3 grasses can subsume C4 grasses.

Care

Like other C4 grasses, Kangaroo grass (Themeda triandra) may not compete well with native or exotic C3 grasses. Garden plants of Kangaroo grass will need to be weeded until the tussocks are more robust. The plants respond well to fertilisers applied at lower strength every two to three weeks during spring to late summer. A light side dressing of blood and bone during the growing season will assist leaf growth.   Do not fertilise or cut during winter as there is little or no growth.  Remove winter dead leaves in spring. Divide unsightly tussocks and divide plants in early spring. Protect from grazing if required or allow native animals to manage the plants.  I try not to plant C4 grasses near C3 grasses. It is my observation that C3 grasses can subsume C$ grasses.

A note on the following Table 1: Features of C3 and C4 grasses in the article, What are C3 and C4 Native Grass? .

Although Themeda is a C4 grass and is considered a warm season grass, it grows tall and well in the lower Themeda grasslands regions of the Australian Capital Territory (eg Yankee Hat) where the winter temperature often falls to well below -10 degrees C for extended periods over autumn, winter and spring. There are a number of diverse types of Themeda triandra, from tall to short, within the species, with each 'type' adapted to a specific micro-environment.  On the other hand Weeping grass (Microlaena stipoides), a C3 grass and a relative of bamboo, thrives well in warm, moist but shady micro-environments.

 

An online page from the New South Wales Department of Primary Industries Agriculture.

 http://www.dpi.nsw.gov.au/agriculture/field/pastures-and-rangelands/native-pastures/what-are-c3-and-c4-native-grass

The perennial grasses can be classified as either C3 or C4 plants. These terms refer to the different pathways that plants use to capture carbon dioxide during photosynthesis. All species have the more primitive C3 pathway, but the additional C4 pathway evolved in species in the wet and dry tropics. The first product of carbon fixation in C3 plants involves a 3-carbon molecule, whilst C4 plants initially produce a 4-carbon molecule that then enters the C3 cycle. Why are these differences important?

These differences are important because the two pathways are also associated with different growth requirements. C3 plants are adapted to cool season establishment and growth in either wet or dry environments. On the other hand, C4 plants are more adapted to warm or hot seasonal conditions under moist or dry environments.A feature of C3 grasses is their greater tolerance of frost compared to C4 grasses. C3 species also tend to generate less bulk than C4 species; however, feed quality is often higher than C4 grasses. Differences between C3 and C4 species are shown in Table 1.

The presence of both C3 and C4 species can be desirable in a pasture as they can occupy different niches (e.g. C3 species are often more abundant in the shade of trees and on southerly aspects, while C4 species often dominate full-sun conditions and northerly aspects) and thereby provide greater ground cover across a range of conditions. It is not uncommon to find both C3 and C4 species in one paddock. This has advantages in providing a broader spread of production throughout the year for both grazing enterprises and native animals.