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Grass trees on Yourka Reserve. Photo Leanne Hales.
Grass trees on Yourka Reserve. Photo Leanne Hales.

Grass trees

Scientific name: Xanthorrhoea

Grass trees epitomise the Australian bush: they’re beautiful, ancient, hardy, thrive in nutrient-poor soils and  respond to wildfire by flowering profusely.

Grass trees are iconic plants, recognisable even to budding botanists. All 66 species are only found in Australia. 

They're all perennial, flowering plants. The smallest species grows to about 1m, others reach 6m tall.

<em>Xanthorroea australis</em> amongst heath at Friendly Beaches Reserve (Tas). Photo Wayne Lawler/EcoPix.

Most species are  extremely slow growing . Studies of some of the taller species found that trunk height increases at about 0.8cm to 6cm per year, but this varies with local environmental conditions 1 . Grass trees are often very long-lived; some are estimated to be 350 to 450 years old! 2

Xanthorrhoea are monocots (meaning they only have one cotyledon, which is the leaf attached to the embryo within the seed). Some form a ‘trunk’ from old leaf bases stacked on top of each other and stuck together by a naturally occurring resin. Some species have a branched trunk, others, like  X. gracilis, don't form an above-ground trunk at all.

<em>Xanthorroea australis</em> at Friendly Beaches Reserve (Tas). Photo Wayne Lawler/EcoPix.

Grass tree leaves are narrow, linear and stiff. Where present, old leaves often hang down and form a ‘skirt’ around the base of the trunk. The length of the skirt is a good indication of the time since the last fire – the longer the skirt, the longer the duration without fire.

Grass trees are even more interesting below the soil surface! They have a root system, where microbes called mycorrhiza surround the roots in a symbiotic relationship, which helps the plant take up nutrients.

Many species have an amazing ability to survive fire. A fire may burn their leaves and blacken their trunks, but the trees usually survive: the living growth-point is buried underground, protected by tightly packed leaf bases. 

In fact, some grass trees are stimulated by fire – in the spring after a summer bushfire, large numbers of plants can flower.

However, not all species are fire-tolerant: the threatened Grey Grass Tree (X. glauca angustifolia), which is found on JC Griffin Reserve in Victoria, is killed by hot fires and needs protection in the fire-prone landscapes in which it occurs.

Grass trees may take several years to flower. Flowers form on a spear-like spike, which can be up to 4m long! Flowers are arranged in a spiral up the spike, and produce a great amount of nectar, attracting a wide variety of insects, birds and mammals.

Lorikeets enjoying flower spikes at Carnarvon Reserve (Qld). Photo Wayne Lawler/EcoPix.


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Once pollinated, the flowers form a tough, pointed fruit capsule that’s typically matt-black. One flowering stem of the X. johnsonii grass tree can produce up to 10,000 seeds! 3

Xanthorrhoea comes from the Greek  xanthos, which means 'yellow or golden' and rhoea which means ‘flowing or to flow’ and refers to the yellow gum or resin that flows from the stem.

The grass tree is important to Aboriginal people across Australia. This resin is traditionally used as glue in spear-making and in patching up water containers.

Grass trees at JC Griffin Reserve in Victoria. Photo Matthew Newton.

Flower spikes make  fishing spear shafts and  firesticks ; the tough seed pods are used as  cutting implements ; and the flower’s nectar forms a sweet, slightly fermented drink.

Grass trees are also known as 'yacca', which is likely derived from a South Australian Aboriginal language, mostly likely Kaurna.

Where do grass trees live?

Grass trees are found in all Australian states and territories, especially on the east and west coast.  The Austral Grass Tree (X. australis) is one of the most widely distributed species, growing in Tasmania, Victoria, New South Wales, Australian Capital Territory and South Australia.

The Grey Grass Tree (X. glauca angustifolia), found on  JC Griffin Reserve, is listed as Threatened under the Flora and Fauna Guarantee Act in Victoria.

Threats to grass trees

Populations of many species of grass tree have been devastated by Cinnamon Fungus. This rots the roots and causes dieback. The disease caused by this introduced plant root pathogen is often difficult to detect and its impact can be considerable before detection. In Australia Cinnamon Fungus infection threatens several plants with extinction.

Further threats include: land clearance for agriculture and urban development; inappropriate burning; overharvesting of foliage and illegal removal of the plants from their natural habitat for sale as garden plants (the species has very sensitive roots and the chance of grass trees growing after translocation is fraught). 5

A grass tree experiencing die back from a pathogen. Photo Wayne Lawler/EcoPix.

What's Bush Heritage doing?

We have grass trees on Chingarrup, Kojonup and Monjebup reserves (WA);  Carnarvon, Reedy Creek and  Yourka (Qld); Burrin Burrin and Tarcutta (NSW); JC Griffin Reserve in Victoria; and in Tasmania on South Esk and Friendly Beaches where the vulnerable Sand Grass Tree is found.

We’re protecting grass trees by halting land clearing, managing fire regimes, and managing total grazing pressure (some species are limited by over-grazing of seedlings).

Donate today to help us continue this and other vital conservation work.

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