Watching Grass Grow

Grasses are an oft-neglected component of bushland restoration. They are usually ignored by wildflower enthusiasts and native gardeners, due to their lack of colourful flowers. They are also often challenging to identify, as they are almost impossible to distinguish when not flowering/seeding. Even when they are flowering, their flower parts (the diagnostic features) are microscopic. On top of all this, their diversity can be overwhelming; the Queensland Herbarium lists 434 species of grasses as occurring in southeast Queensland (the Moreton pastoral district). And this doesn’t include the hundreds of sedges, rushes, and lily-like plants that often disguise themselves as grasses! It is perhaps not surprising that grasses are one of the few plants that have the honour of having a phobia associated with them (agrostophobia). Considering that only one species of grass has made an appearance on this blog in over five years of posting suggests that I might also be guilty of this condition. It is only reasonable considering I’m also allergic to grass pollen (but not other plants!).

This tendency to ignore the grasses is understandable, but a shame. Native grasses are host plants to multiple butterflies, are an extremely important food source for finches, quail and doves, and provide important cover for skinks, snakes and mammals. In contrast, exotic grasses introduced intentionally for the pastoral industry or accidentally as weeds represent some of the worst weeds in Australia, Pine Mountain included. Exotic grasses smother out diverse, native understoreys and vastly increase the fuel load in the vine-scrubs, a habitat that historically rarely burnt. Being able to distinguish the native grasses from the weeds is therefore a fundamental skill when restoring our local vegetation.

^{Native grasses are host plants for many species of near-identical butterflies called “grass-darts”. If you think grasses are tricky to tell apart, these little bastards are almost impossible.}

At our open property day last year, I was asked by a visitor how to tell the difference between native and weed grasses. My response at the time was that the native species tend to be daintier, with more wiry stems than the coarse, vigorous tussocks of the weeds. This, of course, is a broad generalisation, and there is no one rule for distinguishing natives from weeds. Unfortunately, it is a matter of learning each of the species individually and knowing their place (in the bush or the compost heap)

For this reason, I decided to dedicate this post to providing a description of each of the common grasses that grow in Pine Mountain. This list is not exhaustive, but contains the most abundant species I’ve noticed growing in the parts of Pine Mountain that currently support or formerly supported vine-scrub. Note that there are many other species of grasses that can be found on the sandstone-derived soils in the southern half of Pine Mountain, but these are beyond the scope of this post. I apologise at the outset for the quality of the photographs in this post. One thing I quickly realised when I set about photographing all the species mentioned is that grasses are very challenging to photograph well. It is almost impossible to photograph them in such a way that shows off important characteristics of their flowers along with the structure of a whole plant or colony.

I’ve listed the species by the situation in which they are most often observed (paddocks, forest edge or forest interior), as most species have a limited range of shade tolerance.

OPEN PADDOCKS

It is doubtful whether there were any natural open grasslands present at Pine Mountain before Europeans commenced their destruction of the local vine-scrub. Nevertheless, the openings created by the axe would have been soon colonised by grasses adapted to the grassy eucalypt forests and open grasslands of neighbouring districts. Most of the open paddocks that dominate Pine Mountain currently support exotic grasses introduced for the grazing industry throughout the 20th century. However, a few native grasses hold on, and these are described below.

Black Spear-grass, Heteropogon contortus

Black Spear-grass is a native grass that is very familiar to most Queensland graziers. It is a widespread species that grows into moderately sized tussocks, and is a reasonably important fodder species for cattle. It is highly palatable when young, but its protein content is not as high as some of the introduced African pasture species. It is a species that tends to disappear from pastures under heavy grazing pressure. It is a reasonably common species in pastures across Pine Mountain, but never seems to be dominant. Rather, it persists as scattered clumps amongst mostly exotic species. Historically, this species would not have occurred in the vine-scrubs, but would have been a dominant component of neighbouring eucalypt woodlands.

Black Spear-grass is easily recognisable when seeding by its distinctive, coarse, black awns, which twist into dense tangles when wet. The seeds attached to each awn have a sharp tip, which lodge into socks, pants and the wool of sheep. As rain (or sweat) reacts with the awn, it begins to twist, screwing the seed deeper into the skin. This is an effective strategy when a seed is planting itself into damp ground or being dispersed into new habitats, but can be nuisance for people and a health hazard for sheep.

Black Spear-grass grows only in the warmer months. It dies back to the ground every winter, regardless of whether rain falls during the cooler months. It therefore makes a messy garden plant. In areas of our property where I have removed all the exotic grasses and other weeds, Black Spear-grass often spreads rapidly, aggressively competing with the planted trees. For this reason, I usually remove it from around the base of young trees, but leave it in the gaps for erosion control. As the trees develop, they soon outcompete Black Spear-grass, which never grows in the shade of vine-scrub trees, preferring very open, sunny locations.

Barbed Wire Grass, Cymbopogon refractus

Despite its name, Barbed Wire Grass lacks the sharp barbs of its namesake. The flower spikes do, however, bear a resemblance the structure of barbed wire. This is an attractive, clumping species that looks neat throughout the year. It is sometimes planted in gardens, but needs a sunny spot to thrive.

Barbed Wire Grass is closely related to the Lemon Grass, Cymbopogon citratus, used widely in Southeast Asian cooking, and has a similar citrusy scent. Apparently, one can make a tea from the leaves, but I’ve never tried so can’t vouch for its taste.

Barb-wire Grass is a relatively uncommon species at Pine Mountain, where it struggles to compete with introduced pasture grasses. Nevertheless, small clumps often appear in my weeded areas, and these usually form small colonies over the subsequent 2-3 years. These eventually get shaded out as the nearby trees develop.

Forest Bluegrass, Bothriochloa bladhii

Forest Bluegrass is an important pasture species that is widespread across eastern Queensland on heavier soils. It can be recognised by the bluish hue to the leaves and the reddish hue to the flower spikes. Due to its palatability, it is often eliminated by heavy grazing. At Pine Mountain, it tends to occurs in scattered clumps in pastures and is never dominant.

Unlike most other native grasses profiled in this post, Forest Bluegrass curiously doesn’t spread into my weeded plots. I wonder if the young seedlings are targeted by grazing wallabies, or perhaps if I mistake them for a weed grass and remove them? It does grow in our orchard, where it survives intermittent mowing.

Forest Bluegrass cannot compete with aggressive exotic grasses such as Green Panic or Rhodes Grass, but does persist alongside Red Natal Grass and other smaller weed species.

Pitted Bluegrass, Bothriochloa decipiens

Pitted Bluegrass is one of the more common native grasses to occur in local pastures, as it is not particularly palatable to livestock so is tolerant of heavy grazing pressure. Pitted Bluegrass grows up to 1 m tall in small tussocks, but often forms extensive colonies where it can be a dominant species. It is far less common in ungrazed sites, and rarely spreads prolifically in my weed-free plots, which are not grazed (except by wallabies). It also tends to be outcompeted by aggressive exotic species, such as Green Panic and Rhodes Grass, so typically grows in sites that are drier or less fertile.

While Pitted Bluegrass is closely related to the former species, it is easily distinguished by its flower spikes, which are much smaller, lack the reddish hue and, while being digitate, the “fingers” are always held together in an upright position. In contrast, the “fingers” of a Forest Bluegrass flower spike spread apart. The plant itself is also finer-stemmed than Forest Bluegrass, and lacks the bluish colour of the other species.

Queensland Bluegrass, Dichanthium sericeum

The Queensland Bluegrass is similar in structure to the Pitted Bluegrass, growing in small, erect tufts that produce small, digitate flower spikes with “fingers” mostly held together. However, flower spikelets of the Queensland Bluegrass are densely covered with silky hairs, and the spike itself often nods slightly, rather than being held upright. Unlike Pitted Bluegrass, Queensland Bluegrass is a valuable fodder species for livestock.

Queensland Bluegrass is widespread throughout Queensland on clay soils, but has largely disappeared from most locations in southeast Queensland, due to heavy grazing, conversion of grassland into crops, and the proliferation of exotic grass species. It does not appear to be a common species at Pine Mountain, but I have seen it at several locations, from pebbly flats beside the Brisbane River to pastures on red clay loams widespread in the district. At home, it has sprung up in a few of my weeded plots, usually mixed in among a range of other native grass species. Some of the sites it has appeared at home are actually much shadier than I typically associate with this species. However, in such sites, the species is gradually being replaced by more shade-tolerant native grasses such as Echinopogon and Microlaena.

Slender Rat’s Tail Grass, Sporobolus elongatus

There are many species of “Rat’s Tail Grasses”, including a few natives and many serious weeds. Most appear similar and can be challenging to identify. This species appears to be the most common one in Pine Mountain, and fortunately is native. It can be distinguished from its relatives by the fact that each flower spike consists of a series of spikelets that are mostly held pressed against the stem (the lower-most couple of spikelets can be a little lax). Furthermore, the spikelets in the lower half of the flower spike are spaced sufficiently apart that you can see the stem between each spikelet. In related weed species such as Sporobolus fertilis (Giant Paramatta Grass) and Sporobolus africanus (Paramatta Grass), the stem is only visible in the lowest 30% or less of the spike, due to the denser clustering of the spikelets. In contrast, in another native species Sporobolus creber, the stem is visible between the spikelets along the entire length of the flower spike.

Slender Rat’s Tail Grass tends to form small, scattered clumps amongst other grass species. It grows up to 1 m tall. It appears to be much more widespread during this wet summer than in previous years.

On our property, this species mostly grows in areas that receive semi-regular mowing/slashing. It is absent from areas with thick exotic pastures and is scarce in my weeded plots. I suspect it doesn’t compete well with taller, more vigorous grass species. The tiny seeds are also likely spread by the tractor, which explains its poor ability to colonise weeded areas that receive no vehicular traffic. Most of the weed species of Sporobolus are also easily spread on contaminated vehicles, so it is very important to clean all vehicles thoroughly before moving between properties. The last thing Pine Mountain needs is more species of weeds to contend with.

Blown Grass, Lachnagrostis filiformis

This short-lived grass appears in sunny, damp areas following heavy rain. It forms pretty, dense swards along the banks of our dam when it fills. Each plant is only small, and most of their volume comprises the large, open flower spikes, which give colonies a soft, feathery appearance from a distance.

Due to its highly specific habitat requirements, this is not a widespread species at Pine Mountain. However, it can be common in seasonally boggy locations where weeds have been kept at bay.

Small Burr Grass, Tragus australianus

This short-lived grass forms small tufts in degraded sites where there is dry, bare soil. Small Burr Grass forms characteristic flower spikes containing seeds covered in tiny, hooked spines, which attach in abundance to socks and animal fur. Despite being a native species, I suspect this species is a relatively recent invader from more arid areas further west. It takes advantage of the habitat humans have created along roadsides, tracks and other bare ground. I rarely see it in natural habitats or even in pasture.

VINE-SCRUB EDGES AND GAPS

Stout Bamboo Grass, Austrostipa ramosissima

There are two local species of bamboo grass that are common along the edges of vine-scrubs. At least, they were common, but are being outcompeted by the aggressive exotic, Green Panic. They also would have occurred within the vine-scrub itself, wherever tree falls or rock outcrops allowed sufficient light to reach the forest floor. Stout Bamboo Grass is the largest and (in my opinion) most ornamental of the two species.

As the name suggests, bamboo grasses have woody bamboo-like stems that grow in attractive clumps. The Stout Bamboo Grass grows over 2 m tall, and is easily the largest of our local native grass species. It produces large clusters of soft, fluffy seed heads, which are popular among birds for lining their nests.

This species is occasionally planted in suburban gardens, where it is an attractive, ornamental feature. It can look a bit tatty after a few years, but it self-seeds readily, so the original tussock can be dug out and it will be naturally replaced by its seedlings. Unlike real bamboo, Stout Bamboo Grass grows to a much more manageable size for suburban gardens, and is easily removed when no longer desired.

I recommend against planting Stout Bamboo Grass in revegetation sites until the planted trees have reached at least 2 m tall. Otherwise, this fast-growing grass can outgrow the young trees and the shade cast by the grass can inhibit their growth. It spreads rapidly via seed into any sunny gaps, so in an open, newly planted plot, you could easily end up with a bamboo grass jungle before the young trees are able to beat the grass to the light.

Slender Bamboo Grass, Austropstipa verticellata

Slender Bamboo Grass is similar in appearance to Stout Bamboo Grass, but tends to be smaller in stature (1-1.5 m tall) and more often grows in exposed paddock situations. It also appears to be slightly less shade-tolerant, quickly dying off once the canopy establishes overhead.

The most important identification feature for distinguishing this species from the Stout Bamboo Grass relates to the shape of the awn attached to each seed. In the Stout Bamboo Grass, a large percentage of awns have a peculiar right-angle bend midway along their length. In Slender Bamboo Grass, the awns are all straight.

Graceful Wire-grass, Aristida gracilipes

The most important identification feature for distinguishing this species from the Stout Bamboo Grass relates to the shape of the awn attached to each seed. In the Stout Bamboo Grass, a large percentage of awns have a peculiar right-angle bend midway along their length. In Slender Bamboo Grass, the awns are all straight.

This attractive, tussock-forming grass is locally scarce, but there are several colonies in the vicinity of Worlds End Pocket, at the end of Riverside Drive. It is more widespread in eucalypt forests, and wouldn’t have naturally grown in the vine-scrubs that once covered Pine Mountain, except perhaps where rock outcrops led to natural gaps in the canopy.

It forms dense, neatly symmetrical clumps of dainty but wiry stems, and drooping seed heads. I like this plant so much that I’ve planted several groups in the flower gardens around the house. Of all the varied and colourful plants from across Australia that are growing in these gardens, it is actually this local grass that attracts the most comments from visitors. It looks so soft and fluffy it is irresistible to walk past and not touch. It is also very drought-tolerant, staying soft and green through the driest periods without any additional water.

There are more than 50 species of wire-grass in Australia, and all have a characteristic awn that branches into three spikes at the tip. These can easily lodge into socks and pants, and can be a nuisance when walking through extensive areas of grass. Wire-grasses are also not particularly palatable to livestock, so are not popular among graziers.

I’m fairly certain there is a second species/taxon of Aristida (wire grass) that grows in the vine-scrub areas of Pine Mountain, but I’m yet to work out its identity. It is similar to A. gracilipes, but has coarser stems, which are often branched higher up than A. gracilipes, and tends to form more open tussocks. I’ll update this when I work out what it is. It is possibly just a variant of A. gracilipes, but it is distinctive, even when growing side-by-side.

Cup Grass, Eriochloa pseudoacrotricha

There are three native species of Eriochloa (E. crebra, E. procera and E. pseudoacrotricha) that are likely to occur in Pine Mountain, and all three are near-identical. They are all referred to as “Cup Grass”. They differ in microscopic features of their flower parts, and to be honest I mostly dismiss them as “an Eriochloa” rather than carefully check the flowers each time I encounter them. Writing this blog post has forced me to look in detail at the ones growing on our property and they appear to be E. pseudoacrotricha, as the spikelets end in a tiny bristle and the nodes along the stems have tiny white hairs. Cup Grass is an abundant coloniser of my weeded plots, but is rarely encountered otherwise. They don’t seem to be able to compete with exotic grasses.

Cup Grass is a medium-sized, perennial grass that forms large colonies wherever there is exposed soil. They therefore provide good erosion protection for newly weeded sites. It can smother young tree seedlings, so may require removal from around the base of planted trees.

Of all the native grasses mentioned in this post, Cup Grass is probably the most valuable food source for seed-eating birds. The relatively large seeds are popular among Double-barred Finches and Brown Quail. In contrast, most of the local native grass species have very small seeds that are largely ignored by the birds, especially when the juicy seeds of exotic African grasses are widely available in the surrounding landscape.

Cup Grass is generally considered good forage for livestock, although its scarcity in local paddocks probably limits its value in this respect.

Cup Grass bears a superficial resemblance to many other grass genera, such as Paspalum, Brachiaria and Urochloa, which have a similar flower spike arrangement. However, as their name suggests, the tiny spikelets of Cup Grasses sit on a circular, cup-like callus. You’ll need a magnifying glass or macro lens to see this properly, however.

Tall Windmill Grass, Chloris ventricosa

This is a short-lived perennial species that has expanded rapidly within my revegetation plots, where weeds have been removed. It was formerly scarce on our property. It is superficially similar to other digitate grasses (those with flower spikes comprising many “fingers” arising from a central point). It can be distinguished from other local species by the relatively few “fingers” (normally 3-5), which usually sag at their tips. It is a far daintier species than the related weed, Rhodes Grass (Chloris gayana).

The flower spikes are 0.5-1 m tall, but after seeding, the plant usually dies back to a short tuft of leaves that are less than 20 cm long.

Tall Windmill Grass grows locally mostly in the protected semi-shade of forest edges. It doesn’t persist in regularly mown areas, in heavy shade, or in the presence of more competitive exotic grasses. It is readily grazed by cattle, but the small amount of foliage produced limits its value as a fodder species.

Slender Windmill Grass, Chloris truncata

Slender Windmill Grass is another local digitate species, with much longer “fingers” than most other local species. There also tends to be more fingers per flower spike (up to 10), and these are arranged in multiple directions, rather than radiating symmetrically from a central point. Each plant is very short (~40 cm tall), and most of this height is made up of the large digitate flower spikes.

Slender Windmill Grass is another species that has increased rapidly in my weeded plots. It has also spread along tracks and in mown areas of the property, especially where there was previously bare, gravelly ground. This is obviously a good coloniser species that becomes outcompeted by taller, more aggressive native and exotic grasses in more favourable situations.

Slender Windmill Grass is not very palatable to stock (I suspect this is simply because its leaves are so short), so it tends to increase in overgrazed pastures where competition with palatable grasses is reduced.

Like the previous species, I expect Slender Windmill Grass to primarily colonise newly weeded areas, gradually disappearing from older plots.

Slender Cane Grass, Dinebra decipiens

This is a locally uncommon grass that mostly appears in partly shaded areas where weeds have been removed. It is relatively tall (up to 1 m), but forms a very open, spindly clump, with stems that often flop over under the weight of the large flower spikes. The common name is not very apt, as it is no more cane-like than any of our other local grasses, and significantly less so than the two bamboo grasses. It is best recognised by its large, open flower spikes, which are quite unlike any other local species. It superficially resembles Digitaria parviflora, which could occur in our area though I’m yet to find it, but the structure of the flower spikelets looks very different under the microscope (or macroscopic camera lens).

Slender Cane-grass appears to be relatively short-lived and easily outcompeted by other species. It mostly occurs as scattered individuals among other grasses.

Shotgrass, Paspalidium distans

Shotgrass is one of several similar-looking and related species that occur in eastern Queensland. Rather than forming an upright tuft like most of the other Paspalidium, its stems radiate out from a central point, with each stem lying on the ground until the first node, and then each bends upwards. The clusters of tiny, round spikelets scattered along a central main stem is characteristic of the genus.

Shotgrass is not a particularly common species locally, as it tends to be smothered out by exotic grasses. It forms small colonies in my weed-free plots in areas with partial shade.

Nodding Hedgehog Grass, Echinopogon nutans var. nutans

This attractive, dainty grass is a common plant in sheltered, semi-shaded locations. It is absent from open areas (where it is out-competed by larger species) and heavily shaded situations (such as intact vine-scrub), but appears to rapidly colonise the middle ground. The boundaries of colonies appear to constantly move in accordance with the ever-changing canopy conditions and abundance of competing grass species in revegetation plots.

It is relatively nondescript for most of the year, but following rain in late spring and early summer, it produces masses of attractive flower spikes that give Nodding Hedgehog Grass its name.

This species is usually outcompeted by Green Panic in most situations where it would have otherwise grown, but has spread quickly through many of my restoration areas once weeds have been removed. It usually grows less than 0.5 m in height so doesn’t compete heavily with my planted trees.
I have noticed that the leaves of Nodding Hedgehog Grass, despite being broad, dark green and tasty-looking, are almost never touched by hares or wallabies. This may be due to the fact that, when touched in the direction of growth, the stem and leaves are extremely rough and sharp. However, a second reason was discovered by scientists back in the 1990s. Apparently, Nodding Hedgehog Grass is one of a handful of Australian grasses that contain a fungus that grows in the intercellular spaces in the leaves and seeds. This fungus is passed to the next generation of grass through the seed. When eaten by sheep, cattle, horses and camelids, this fungus causes “staggers” (fine tremors of the head, stiff movements and incoordination). It can even lead to permanent neurological damage if consumed excessively. The fungus thus benefits the plant by deterring herbivory. I don’t know whether birds are equally affected by the fungus, but I have never witnessed finches eating the seeds of this grass.

Nodding Hedgehog Grass is occasionally sold as a garden plant at specialist native nurseries, and when it is flowering, it would make an interesting feature plant. However, I suspect it would look weedy for most of the year in a suburban garden, as it doesn’t form a neatly shaped tussock. It goes without saying that you shouldn’t intentionally plant this species where it might be eaten by livestock.

Weeping Grass, Microlaena stipoides

This dainty grass grows in similar, sheltered locations to the Nodding Hedgehog Grass, and the two species often form mixed lawns. Weeping Grass often grows along our slashed tracks where there is light tree cover and is clearly tolerant of regular mowing. It is sometimes even marketed in temperate regions of Australia as a native alternative to the more usual lawn grasses.

However, at Pine Mountain, I never see it growing in exposed, sunny locations, so I think we are near the edge of its climatic tolerance (further north in Queensland, it is largely confined to cooler mountainous locations). For this reason, I doubt it would perform well as a lawn in our hot, dry climate, unless partly protected by trees and buildings.

Weeping Grass apparently produces valuable fodder for livestock in temperate regions of Australia. While this is probably also true locally, the small stature of the species limits the quantity of feed produced, compared to the robust exotic pasture grasses.

Weeping Grass is an attractive component of the forest understorey wherever litter-fall is sufficiently sparse so as to not smother it out. It is small enough to represent a negligible fire risk, and it does not compete aggressively with planted trees.

Short-awned Wheat Grass, Anthosachne kingiana subsp. multiflora

Short-awned Wheat Grass is a species I wasn’t familiar with before moving to Pine Mountain. Like many of the species growing in semi-shaded environments at the forest edge, it is very nondescript when not flowering or seeding.

I rarely see this species where there are exotic grasses, but it has become one of the most numerous grasses in my restoration plots, where it forms large colonies. It sometimes grows in mixed meadows of Microlaena and Pentapogon, but oftentimes forms a monoculture. Like Weeping Grass (Microlaena stipoides), the flower spikes of Short-awned Wheat Grass nod downwards. However, the latter is a taller, more robust species, and the leaves are more bluish-green, rather than the bright green of Weeping Grass.

I’m not aware of how valuable this species is for grazing. Studies by CSIRO found Short-awned Wheat Grass to be one of the species that declines in density when grazed, which suggests that it is eaten (or at least, trampled). It also doesn’t persist in our mown areas, which suggests it is intolerant of regular pruning, whether by a slasher or the teeth of cattle. In the absence of cattle on our property, it can form dense swards that compete with newly planted trees. For this reason, I usually remove it from the vicinity of seedlings until the latter establishes.

Shorthair Plumegrass, Pentapogon (Dichelachne) micrantha

Two local plumegrasses have sprung up on our property in plots where I have removed the weeds. The Shorthair Plumegrass appears to be the less widespread of the two, but forms large colonies where it does grow.

Plumegrasses are closely related to the Nodding Hedgehog Grass, and grow in similar sheltered locations. A plumegrass native to New Zealand has been confirmed to contain the same (or a related) fungus as Nodding Hedgehog Grass, although it is unknown whether this is true for the Australian species. This seems likely.

Longhair Plumegrass, Pentapogon (Dichelachne) crinita

On our property, Longhair Plumegrass appears as widely scattered clumps in sheltered locations within my weeded plots. Its flower spikes are arranged like bottle brushes. As with the former species, when not flowering, Longhair Plumegrass is very easily overlooked among the other small, dainty native grasses with which it shares its sheltered forest edges.

VINE-SCRUB INTERIOR

Very few grasses grow naturally in the shady interior of vine-scrubs. Only three species are widely observed at Pine Mountain. Both are often outcompeted by the aggressive understorey weed, Rivina humilis (Corry Berry), so tend to only occur where large boulders or good fortune have dissuaded the growth of this weed.

Hooky Grass, Ancistrachne uncinulata

This unique grass is recognisable even when not flowering or seeding by its tangled clump of branched, deep-green, wiry stems, giving it the appearance of a shrub. It is even more distinctive when seeding, as the seeds stick to clothing (and presumably animals) like Velcro. It can grow in very shaded locations, but grows larger and denser where dappled light reaches the forest floor.

Hooky Grass would have once been a dominant component of the vine-scrub understorey prior to invasion by Green Panic and Coral Berry. It therefore provides important shelter for Black-breasted Buttonquail and other inhabitants of the forest floor, once the weeds are removed. Despite its adaptions for seed dispersal, Hooky Grass is relatively slow to colonise weeded areas on our property. Most of those that grow in my revegetation plots are those I planted or those that were uncovered under a sheet of Cats Claw Creeper. Hooky Grass doesn’t appear to compete well with the faster growing native grasses (and saltbushes, Einadia spp.) that quickly form mats in any of my plots that are yet to achieve canopy closure. I expect this species will become more dominant over time as the other species are shaded out by the developing trees.

Despite its wiry stems, Hooky Grass is eaten by cattle, but I doubt it is a favoured food. I have never seen it grown as a garden plant, but it has a certain quirky appeal for a shaded location.

Beard Grass, Oplismenus aemulus

This spreading, prostrate species is also sometimes called “Australian Basket Grass”, although neither this nor “Beard Grass” is very descriptive. In the vine-scrubs, this is a weakly trailing groundcover, which sprawls delicately among the rocks and litter. However, when allowed to grow in a sunnier position without competition from weeds and other grasses (as occurs in the early years of development within revegetation plots), Beard Grass is a rampant spreader, which forms thick mats that smother seedlings and other groundcover species. Gardeners be warned before introducing this one into your yard!

Beard Grass spreads rapidly via runners in wet conditions, only to experience extensive die-offs when the dry returns. There are a couple of other Oplismenus species that are native to southeast Queensland that are similar in appearance to Beard Grass (these have narrower leaves and less spreading flower spikes), but I am yet to find either of these at Pine Mountain. The similar-looking Graceful Grass (Ottochloa gracillima) also has much narrower leaves than Beard Grass and very different flower spikes.

Graceful Grass, Ottochloa gracillima

This groundcover species is similar in growth form to Beard Grass. Despite being an abundant species in bushland areas of Brisbane and other wetter parts of southeast Queensland, it is surprisingly scarce at Pine Mountain. I have only found it at a couple of remote locations in the Corbould Reserve, always on sheltered southern slopes in rare places where Coral Berry (Rivina humilis) is yet to invade. I suspect Pine Mountain is at the drier end of the species’ tolerance, and Coral Berry has displaced it from most locations where it would once have grown.

Like Beard Grass, colonies of Graceful Grass expand and retract depending on rainfall conditions. It is tolerant of moderately heavy shade, and can spread prolifically in suburban gardens.

COMMON EXOTIC GRASSES

Like most of eastern Queensland, Pine Mountain has been invaded by a broad range of exotic grasses. Most of the grasses you see here are not native. Many of these were deliberately introduced as pasture species, while others stowed away in hay, in garden material or on contaminated equipment. Those featured below are not an exhaustive list, but are meant as an introduction to the most common weed grasses one is likely to encounter in Pine Mountain.

Green Panic/Guinea Grass, Megathyrsus maximus

This African species is one of the greatest threats to the vine-scrubs of Pine Mountain, thriving in semi-shaded environments beneath the forest canopy and producing a thick, highly flammable fuel load during dry conditions. As most local rainforest tree species are sensitive to fire, any fire that does occur could be devastating. This species is one of the most widespread exotic grasses in Pine Mountain, and is easily the most abundant exotic grass in shaded, forested environments.

‘Green Panic’ and ‘Guinea Grass’ are two names for different varieties of the same species (varieties trichoglume and maximus, respectively). Green Panic is by far the most abundant variety locally, although Guinea Grass also occurs, especially in wetter locations along creek banks. The two forms are similar, but Guinea Grass is a much taller, more robust beast. Guinea Grass usually grows 2-3 m in height, while Green Panic is usually around 1.5 m. Green Panic also has soft hairs on its flower spikes.

Green Panic is a valuable fodder species, which is why it was introduced to the region. Having evolved among herds of antelope, elephants and rhinoceros, it is also very fast-growing and tolerant of grazing, trampling, slashing and other forms of abuse. The same qualities that make it an ideal fodder species unfortunately make it challenging to eradicate from forested areas. Green Panic can germinate and begin flowering and seeding within one month of heavy rain. It is therefore crucial, if it is to be eradicated from a site, that treatment of seedlings (herbicide or hand-pulling) takes place within the first few weeks of rain. I have seen countless bushland restoration efforts fail due to inadequate control of this grass. If unchecked, Green Panic will quickly outgrow and smother any young tree seedlings planted. Controlling this weed without damaging the tree seedlings then becomes very challenging.

For all the above reasons, Green Panic is one of the major targets of my restoration efforts at home. This is especially true over the warm, wet summer months, when grass growth is especially prolific. In the drier winter months, I tend to shift my focus to cats claw creeper, asparagus and other weeds that are slower to mature (and less urgent to deal with in wetter conditions). Success depends on a very simple principle: never let it seed. In practice, this means reacting quickly after each rain event to the carpets of young seedlings that emerge. I find that it takes approximately three years for the soil seed bank to be exhausted. Only scattered seedlings emerge in the fourth year, and none by the fifth year. So far, I’ve successfully removed this weed from about 2 ha of our property.

Green Panic has one redeeming quality: its seeds are a very popular food source for local birds. Every summer and spring, local residents will be very familiar with the masses of doves, finches and quail that insist on feeding on local dirt roads, narrowly avoiding passing cars. The fallen seeds of Green Panic are what they are feeding on. These are much easier for birds to find on adjacent bare ground than within the actual dense grass thickets, which is why the birds are drawn to the roads. It is a good idea to drive slower at this time of year, for this reason.

Johnson Grass, Sorghum halepense

This monster of a grass is similar in size to Guinea Grass, but the large reddish brown seed heads are characteristic. It has coarse stems and broad leaves that are easy to recognise even when it is not flowering or seeding.

Like Guinea Grass, Johnson Grass favours disturbed, damp spots like roadside ditches. Fortunately, it rarely forms dense swards. Instead, it is usually seen as scattered tussocks in amongst other weedy grasses like Green Panic and Rhodes Grass.

Johnson Grass is a moderately valuable pasture species, although the leaves may contain toxic levels of nitrates under certain conditions. It is a very costly weed of cropping land, and sometimes invades natural areas, especially along creeks. It is currently a relatively minor weed around Pine Mountain.

Red Natal Grass, Melinis repens

Red Natal Grass is named after the former province of South Africa (now KwaZulu-Natal), where this weed originated, rather than the adjective for birth. It is pronounced accordingly, with emphasis on the second syllable.

In Pine Mountain, this is one of the most abundant constituents of open, sunny pastures, especially in sites that are too dry or infertile for Green Panic. It performs poorly in the shade of trees, where it is usually outcompeted by other grasses. It is also relatively small in stature (1 m or less in height). For these reasons, Red Natal Grass is a much lower fire threat to intact and regrowth vine-scrubs than Green Panic. It is, however, a nuisance in newly planted revegetation sites. Like Green Panic, it germinates and grows rapidly after rain, swamping any young tree seedlings. It is an aggressive competitor for water and nutrients, so impairs the growth of young trees if left unchecked. Like Green Panic, the soil seed bank takes about three years to be exhausted. However, as the fluffy pink seeds are wind-dispersed, new seeds arrive each year. This ongoing colonisation is a relatively minor issue, however, as the number of grass seedlings is generally small and the shade of the developing trees reduces Red Natal Grass’s competitiveness after three years. I find that it is really only an ongoing issue around the edges of my planted areas, where the flow of new seed is greatest.

Despite being introduced for the grazing industry, Red Natal Grass is not particularly palatable to livestock and has low nutritive value. Cattle do eat it, however, and Red Natal Grass can disappear under very heavy grazing pressure, when it is replaced by even less palatable species. The fluffy seeds are only occasionally eaten by birds.

Rhodes Grass, Chloris gayana

Rhodes Grass is a vigorous, stoloniferous (growing via runners) species that is common along roadsides and in paddocks. It is good fodder for cattle and horses when young, but becomes low in protein as it ages. Our wallabies rarely eat it.

Rhodes Grass is far more tolerant of regular mowing than the previous two species, so is difficult to eradicate from our slashed tracks and lawns. It also appears to be semi-tolerant of glyphosate, and often requires repeat treatments to eradicate it from restoration plots. It appears to spread primarily by runners, and the number of seedlings that appear after rain is generally low, even in young restoration plots. It also appears to be poor at long-distance dispersal, so is rarely a problem away from the edges of restoration plots.

While not as serious a weed as Green Panic, Rhodes Grass can pose a serious fire hazard along the forest edge. Its seeds are rarely eaten by birds.

Feathertop Rhodes Grass, Chloris virgata

Feathertop Rhodes Grass is similar in appearance to Rhodes Grass, but the fingers of the flower spikes are held together upright. It is also lower growing and much shorter-lived.

I suspect that this is a relatively recent coloniser of Pine Mountain, as it is primarily restricted to roadsides, where it has been exploding in density over the past three years. Before this time, it was a scarce species locally, so I suspect it has been introduced and spread by roadwork crews. It is now one of the most abundant grasses along Riverside Drive.

Unlike Rhodes Grass, Feathertop Rhodes Grass spreads prolifically by seed. It is a relatively recent coloniser of our property (only in the last two years, and only near the road), but its rapid spread has kept me busy trying to contain it. It is a species that doesn’t appear to be too tolerant of competition, so mostly appears where there is bare ground. It is too early to tell whether it will successfully invade established pastures and natural areas.

Elastic Grass, Eragrostis tenuifolia

Compared to all the above exotic species, Elastic Grass is a fairly benign invader. It is a small plant (usually around 30 cm tall) that usually grows in dry, gravelly sites where other grasses struggle to survive. It typically forms small colonies of tufted individuals.

Elastic Grass is very tolerant of traffic, and most often grows on driveways, roadsides and in bare patches in lawns. I rarely find it spreading into restoration plots or forested areas, and it is easily removed.

Signal Grass, Urochloa decumbens

Signal Grass is thankfully not too widespread (yet) at Pine Mountain. This aggressive invader forms dense, 1.5-m-tall mats that completely smother out all other species…even other exotic grasses. There are a few colonies along roadsides, but I am yet to see it invade on a broader scale. The same can’t be said for elsewhere in southeast Queensland, where it smothers entire eucalypt forests, creekbanks and other natural situations. Where it grows, little else can, due to the incredible density of the swards. For these reasons, I have eradicated the one medium-sized colony that grew on our property.

While its flower spikes bear a superficial resemblance to native Cup Grass and exotic Paspalum, the dense, hairy foliage of Signal Grass makes it easily recognisable even from a distance.

Signal Grass has the propensity to be a serious weed at Pine Mountain, producing huge fuel loads and displacing diverse native understoreys. While it is a useful pasture species for cattle, horses don’t touch it. In fact, it can become a serious weed in horse-grazed pastures, as it displaces more palatable grass species.

Prairie Grass, Bromus catharticus

Prairie Grass is a small, short-lived, tufted grass that grows mostly in winter, seeding in spring and early summer. It prefers damp, semi-shaded locations without competition from other species. As such sites are not common, it is mostly observed in shady parts of lawns or in my restored plots where other exotic grasses are removed.

Because it matures quickly and grows at a time of year when few other weeds are sprouting, Prairie Grass often escapes my attention until seeds are starting to form. For this reason, it has tended to linger in low densities even in my oldest plots. It is a fairly benign presence, however, and I expect it to completely disappear once the canopy fully develops and a dense layer of litter forms.

Liverseed Grass, Urochloa panicoides

Liverseed Grass is another small weed grass that mostly invades highly disturbed situations like roadsides, driveways and bare patches in pasture. It tends to form colonies that sprout up each spring, each plant forming a low, sprawling tuft. Colonies die off each autumn.

Liverseed Grass was apparently introduced as a pasture grass, but under some environmental conditions can develop concentrations of nitrates that are toxic to cattle. It has become a costly weed of cropping land. In forested environments, it is currently a fairly benign weed. However, I suspect it is a relative newcomer to the Pine Mountain area, as it seems to be expanding its range each year.

Crows Foot Grass, Eleusine indica

Crows Foot Grass is a common weed of gardens, lawns, and other highly disturbed environments. It is a short-lived, semi-prostrate species that occasionally spreads into my weeded plots, but is easily removed and a relatively benign weed.

Awnless Barnyard Grass, Echinochloa colona

This medium-sized, sprawling tufted grass grows primary in waterlogged locations (flooded ditches, dam edges, etc). It is generally a scarce species around Pine Mountain, but has been more obvious than usual this summer, as a result of the wet conditions.

Paspalum, Paspalum dilatatum

Paspalum is a widespread weed of lawns across much of Australia. It can grow up to 1 m tall, but as it is tolerant of regular mowing, it is often much shorter. I rarely see this grass in local pastures or natural habitats; instead, it appears to be largely confined to lawns and other highly disturbed environments.

It is apparently a useful fodder plant for cattle, but I suspect that it isn’t particularly competitive against other exotic and native pasture grasses in grazed situations, or else it would be more widespread locally.

Paspalum seed has low viability and the species spreads slowly vegetatively. It is therefore an easy weed to control if it spreads into my restoration plots.
The flower spikes bear a superficial resemblance to the native Cup Grass, but these two species generally occupy quite different habitats; Paspalum is largely confined to lawns, where it occurs in scattered tussocks, while Cup Grass rapidly forms large colonies on bare ground in weeded areas.

A second species of Paspalum (Bahia Grass, P. notatum) is also a weed of lawns in Pine Mountain. It can be distinguished by the regular Paspalum by the flower spikes having only two branches. Both species occupy similar habitats and rarely spread into natural areas or even grazed paddocks.

^{Bahia Grass, Paspalum notatum}

Green Couch, Cynodon dactylon

This well-known lawn grass is a common species in heavily grazed Pine Mountain paddocks, especially on the more infertile soils. It is rarely a serious weed of vine-scrubs, as it performs poorly in shade.

Like all the lawn grasses, Green Couch spreads via runners to form thick, low mats. It is extremely tolerant of mowing and grazing. It is often dominant in areas that are seasonally inundated, like the bed of our dam when it is dry, and the pebbly flats beside the Brisbane River.

Queensland Blue Couch, Digitaria didactyla

Queensland Blue Couch is sometimes thought to be a native species, although the Queensland Herbarium considers it to be introduced. It is superficially very similar to Green Couch, and often grows together in the one lawn. It differs by the bluish colour of the leaves and the flower spikes that mostly have two fingers (rarely three or four). In contrast, Green Couch is a light green colour, has thinner leaves, more wiry stolons and has flower spikes that usually have four or five fingers.

Like Green Couch, Queensland Blue Couch mostly grows in sites with heavy grazing pressure or that are regularly mown. It is very common on the more fertile, redder soils of Pine Mountain, where it far outnumbers Green Couch. Queensland Blue Couch tends to also be better able to invade semi-shaded situations, although disappears under heavy tree cover. I consider Queensland Blue Couch to be a relatively minor weed of my restored plots. It is a dominant component of the lawns that grow on our mown tracks, where it serves a useful role of protecting the soil. Occasionally it will send off runners into the adjacent bushland, but I’m pretty quick to remove these. Once my trees are more mature, I don’t anticipate Queensland Blue Couch being a threat to my restored plots.