Grasses: Habits and Habitats
This is the text of a brochure available from Friends of Grasslands. Contact Us for printed copies.
A key aim of Friends of Grasslands (FoG) is to encourage conservation of our natural grassy ecosystems, such as natural grasslands (essentially treeless areas), and woodlands and forests where grasses and wildflowers dominate the ground storey. An essential part of good conservation management is an understanding of the plants. This brochure discusses the grasses which dominate grassy ecosystems.
Grasses dominate many natural ecosystems worldwide, and some grasses that have been cultivated have become food staples (wheat, rice and barley), while others provide essential pastures.
Aboriginal people were heavily dependent on grasses because many animals which were important to them thrived on these grasses. Grasses were also important in making flour and artefacts. A better understanding of Aboriginal use of indigenous plants is now emerging.
For many years after settlement, native grasses were the mainstay of a successful pastoral industry, and only after years of unsustainable grazing practice were nature pastures considered unproductive. The use of nature grasses in agriculture is being revived as it is recognised they can withstand Australian weather conditions and require little assistance by way of fertilizer input. Stipa Native Grasses Association’s key message is that high profits can result from low output-low input grazing.
From a conservation perspective, native grasses are the dominant plants in grassy ecosystems and therefore understanding them and their ecology is a key element in keeping and recovering our native grassy ecosystems. In future we may find many more uses for our amazing grasses.
Key to understanding native grasses
There are numerous species of grasses. In the Southern Tablelands of NSW and ACT alone there are 230 grass species, 144 native and 87 introduced species. The discussion below is confined to the Southern Tablelands. Also see addendum for more information.
Grasses are complex plants and understanding their form and structure (morphology) is the key to their identification. However, this brochure only touches morphological characteristics.
Grasses like other flowering plants have flowers and produce seeds. The flowering time is known as anthesis and the flowers are delightful in their structure and colour but are best seen through a hand lens or microscope. Understanding the structures surrounding the seed is often the best way to identify individual species.
One way to get to know grasses is to understand their habitats – each grass species has a preferred habitat, where it is best adapted and able to compete against other plants.
Some grasses are dominant whereas others are often single plants scattered through grassy patches dominated by other grasses.
Different grasses adopt different strategies to spread. Some are colonisers – their seeds are easily dispersed and will quickly establish in bare areas. Others are more cumbersome and do not colonise new areas quickly, but once established tend to dominate by out competing other plants. Kangaroo grass is a good example of this.
Grasses grow and produce seed at different times of the year. This can also be an aid in their identification. Cool season grasses which grow in cool, wet to dry areas, fix carbon in molecules containing three carbon atoms, known as the C3 (C3) pathway. Hot-season grasses, which grow best in warm, moist to dry areas, mostly fix carbon in molecules consisting of four carbon atoms, the C4 (C4)pathway.
Flowering plants fall into two major groups: monocots (send up a single leaf from the seed), and dicots (send up two leaves from the seed) – most plant species fall into the later category. Grasses are monocots, as are sedges, rushes, lilies, orchids and a number of water plants. An interesting characteristic of monocots is that the veins in their leaves are parallel.
Where do grasses grow?
Grasslands are obviously sunny places and woodlands and forest less so. Like many plants, sun, water and soil nutrients are key determinants of where grasses grow best. In the valley floors, deep soils and water availability tends to favour certain grasses over others. Soil nutrients and water availability tend to decrease as one moves up the slope – favouring those plants best adapted to those conditions. However, along drainage lines, greater availability of water and possibly nutrients may mean that plants with a higher water need may be found there.
The more moist the grassland, the higher the conservation value as this type of grassland has been the most affected by intensive grazing and the introduction of exotic grasses.
So our first habitat classification can be based on water availability: very moist, moist, dry and very dry, and in fact different grassland types (ecosystems) are often described in this way. Let us explore this a little further:
River tussock grassland
Very moist grasslands are to be found along rivers and creek lines and tend to be dominated by river tussock (Poa labillardieri) with a few forbs such as woodruff (Asperula conferta), vanilla lily (Arthropodium milleflorum), pale ever lasting daisy (Helichrysum rutidolepis), and sometimes sedges. However river tussock prefers to avoid very wet locations, where a range of sedges and matgrass (Hemarthria uncinata) do well.
It is interesting that river tussock is favoured in garden and road side plantings of native grasses where emphasis is on water saving. These grasses love water but their extensive root systems make them good drought survivors.
Kangaroo grass (Themeda Australis/triandra) is a dominant grass and in most conditions the inflorescence can grow over a metre tall. In wet-themeda grasslands, kangaroo grass and Poa sieberiana species co-dominate. A good example of this may be found on Old Cooma Common, a grassland reserve established by FoG. Taller plants may be found in such grasslands such as vanilla lily, mildmaids (Burchardia umbellata), andmountain psoralea (Psoralea tenax).
In drier areas, kangaroo grass still dominates but grows somewhat shorter and Poa sieberiana tends to replaced by wallaby and other grasses. The richness of forbs increases as the inter-tussock space opens up allowing more colonising by other plants. As grasslands become drier, kangaroo grass tends to be replaced by other grasses such as purple wire grass (Aristida ramosa) and short wallaby grass (Austrodanthonia sp.), but this replacement may be due to degradation of the grassland.
Red-anthered wallaby grassy woodland
Red-anthered wallaby grass (Joycea pallida) is often dominant in dense woodland and forest. Sometimes this grass is found without tree cover which is often interpreted as a sign that tree cover has been removed, i.e., the area is regarded as secondary grassland. Secondary grasslands are native grasslands which have survived or evolved following tree clearing – they may be evidenced by stumps or holes left by trees, situation in landscape, etc. Remnant secondary grasslands are usually classified to the ecological community from which they are derived. For example if remnant secondary grassland was originally part of box woodland, it is regarded as part of the box woodland ecological community.
Spear grasses (Austrostipa spp.) and wallaby grasses (Austrodanthonia spp.)are dominant in many grasslands, and often grasslands are described as short-stipa, tall-stipa, or wallaby grassland, and this is an apt description.
However, evidence suggests that such grasslands were once themeda grasslands where cattle’s preference for eating kangaroo grass, and over grazing and other impacts, saw less palatable spear grasses and wallaby grasses replace them. Tall spear grass (A. bigeniculata) is often dominant in moist grasslands and short spear grass (A. falcata) is often dominant in dry grasslands.
Many FoG members will be familiar with marine grasslands, those that grow along the coast. There are two communities, those dominated by kangaroo grass, which has a somewhat different form compared to that found on the Southern Tablelands, and those dominated by hairy spinifex (Spinifex sericeus). The kangaroo grass grassland shares many plant species with temperate grasslands found on the Tablelands, while Spinifex which grows on sand dunes is a very different, and is a highly salt tolerant community.
So-called pasture improvement saw the deliberate introduction of a number of non-native grasses, such as canary grass (Phalaris spp.), various African lovegrasses, and many more, while other grasses were introduced accidentally, sometime as packing material. Some grasses would be regarded as agricultural weeds, i.e., they are harmful to stock or interfere with crops, while all would be regarded as environmental weeds, plants that can out compete native plants leading to a loss of biodiversity. So far no biological controls have been found for these plants.
Like native grasses, introduced grasses have their own preferences. Grasses like African love grass and serrated tussock prefer drier areas, and canary grass and Chilean needle grass prefer more moist areas.
Nature strip ecology
Canberra’s nature strips are wonderful examples of evolution in action, with short spear grass, short wallaby grass, and African lovegrass vying for places in the sun on hard baked nature strips, while Chilean needle grass takes over on the more shady and wet nature strips.
Thumbnail sketches of native grasses on the Southern Tablelands
There are seventeen native and five introduced poa species. Amongst the native species, river tussock (often referred to as poa tussock) dominates the moister areas of grassland, Poa sieberiana (sometimes called snow grass or poa tussock) is found in higher areas, often in association with kangaroo grass, while a delightful smaller poa (P. meionectes), varying in colour from green to blue is found in highly wooded areas. It is very difficult to tell the difference between river tussock and Poa sieberiana, especially when the latter is large. Poa sieberiana has many varieties and one or two subspecies. Amongst the introduced species, annual poa (Poa annua) is a common annual grass.
If you only know one grass species it should be this one, as it is a dominant grass species of temperate and northern grasslands, and its distinctive inflorescence makes it easy to recognise. When the inflorescence is absent, its rusty red-brown colour may be confused with redleg grass or wild sorghum.
There are twenty species of wallaby grass (Austrodanthonia spp., previous in genus Danthonia), many of which dominate areas of grassland. Another common name for this group of grasses is whitetop, referring to the fact that their inflorescences turn a distinctive white after flowering.
Red-anthered wallaby grass (Joycea pallida), which was originally in the genus Danthonia, is a striking grass usually growing as a monoculture of somewhat spaced plants in drier woodland and forest areas. It gets its common name from the fact that part of its inflorescence is a bright reddish orange.
There are twelve native spear grasses (Austrostipa spp.). Spear grass gets its name from its seed with the attached awn which resembles a spear. The seeds, which can burrow into animals and clothing, are excellent vectors for dispersal. The awn also assists the seed to burrow its way into the soil. The common grasses, tall spear grass (A. bigeniculata – bi-geniculate - its awn bends twice), and short spear grass (A. falcata), also known as corkscrew grass, because its awn looks like a corkscrew, have come to dominate moist and dry grasslands respectively.
Weeping grass (Microlaena stipoides) gets its common name because the stalk which holds its inflorescence bends right over – it has been called ‘loop grass’ for this reason.
This is a bright green grass which flattens out when grazed and loves wet shady spots, an ideal lawn and shady pasture grass. Often overlooked because it is sometimes described as an understorey grass – it grows beneath other grasses. Look hard it you don’t see it, it is very common in grasslands and woodlands. It is also often found as bright green patches in drainage lines. It is making a, sometimes uninvited, comeback in the gardens of Canberra.
Three awn grass
Three awn, wire or kerosene grass (Aristida ramosa) is a very spindly grass that grows in dry and sometimes shady areas which seems to respond to both poor soil and water supply.
Red leg, panic and windmill grasses
Red leg grass (Bothriochloa macra), hairypanic (Panicum effusum), and windmill grass (Chloris truncata) share the characteristic, along with some spear grasses, of being opportunists ready to colonise new areas.
Redleg grass can often be confused with kangaroo grass when not in flower because the colour of both is similar. However, the inflorescences are very different.
There are two species of native panic and four introduced species. Its small round seeds are pretty conspicuous and the plant often looks a little weedy.
The inflorescence of windmill grass is a distinctive large windmill-like structure, similar to some couch, although the couch inflorescence is much smaller.
Some non-dominant grasses
There are four native and three introduced lovegrasses (Eragrostis spp.). The native species are found sprinkled amongst other grasses, while the introduced grasses include the dreaded African lovegrass. A charming and identifying characteristic of lovegrass is that the lemmas at the end of the spikelet neatly fit inside one another.
Plume grasses (Dichelachne spp.), of which there are seven native species, are so called because their inflorescence, usually white, looks like a plume which opens somewhat as it matures.
Other grasses sprinkled amongst grassy ecosystems include wheat grass (Elymus scaber), hedgehog grass (Echinopopon spp.), and nine awn grass (Enneapogon spp.)
Two grasses are considered rare, namely wild sorghum (Sorghum leiocladum) and barbed wire grass (Cymbopogon refractus). The rarity no doubt occurs because, like kangaroo grass, they are preferred by introduced grazers. Interestingly, kangaroos do not seem to like wild sorghum and it can often be found as a clumpy grass ignored in an otherwise eaten grassland.
Wild sorghum can be mistaken for kangaroo grass when it lacks its inflorescence as both grasses are C4 and tend to be a rusty red colour, but their inflorescences are very different. Additionally sorghum has a white ballerina skirt around part of its stem which helps to identify it. It prefers sunny dry grassland areas.
The inflorescence of barbed wire grass looks like barbed wire. The plant likes moist woodland areas.
There are some grasses that grow in water such as swamp wallaby grass (Amphibromus spp., of which there are two species on the Southern Tablelands), common reed (Phragmites australis), and cumbungi (Typha spp., of which there are also two species on the Southern Tablelands). Matgrass (Hemarthria uncinata) can also tolerate some inundation. As its name suggests it forms a tight mat-like appearance.
There are now many useful references and weed identification books. They include:
Joan Gibbs, Grass identification manual for everyone, a pictorial guide to recognition of native and naturalised grasses in the Northern and Southern Lofty Botanical Regions of South Australia. Native Grass Resources Group Inc, South Australia, October 2005. ISBN 0 646 41619 7.
David Eddy, Dave Mallinson, Rainer Rehwinkel, and Sarah Sharp Grassland flora, a field guide for the Southern Tablelands (NSW & ACT), 1998, Environment ACT, NSW NPWS, WWF Australia, ANBG, DLWC, and Environment Australia. ISBN: 0 7313 6021 4.
D.J.B. Wheeler, S.W.L. Jacobs, R.D.B Whalley Grasses of New South Wales, 3rd edition 2002, University of New England. ISBN 1 86389 783 6.
Flora of Australia, Volume 44B, Editor Katy Mallett, Poaceae 3, 2005, Melbourne, Department of the Environment and Heritage and CSIRO Publishing. ISBN 0 643 06960 7.
Addendum: more on grasses
There are numerous species of grasses. In the Southern Tablelands of NSW and ACT alone there are 230 species, 144 native and 87 introduced, representing 71 genera – 32 genera contain native species only, 12 contain both native and introduced species, while the remaining 27 genera contain introduced species only. The table below provides a summary of the numbers of native and introduced species to be found in each genus.
Grasses of the Southern Tablelands
Number of native and introduced species by genus
# contains both native and introduced species.
* generally contains introduced species only.
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