Grass trees are an iconic Australian plant, comprised of 66 species, that are found in all states and territories.
The plant starts off as a small crown of rigid grass-like leaves and after many years of growth, the plant forms a unique ‘trunk’ that is made up of accumulated leaf bases. These leaf bases create a hollow ring where nutrients are transported through aerial roots that run down the centre of this ring.
This plant has the ability to produce copious amounts of resin, which is a distinctive feature of Xanthorrhoea’s. The word Xanthorrhoea originates from the Greek word xanthos, meaning yellow and rheo, meaning ‘to flow’ which refers to the resin.
Xanthorrhoea are extremely resilient to fire. The living growth is shielded by the old, dead leaf bases of the trunk and are provided protection from the tightly packed, moist, young leaves. Many species will respond very well to fire and flower profusely, as the nutrients from the burnt leaf skirt fertilise the plant.
The Flowers of Xanthorrhoea sp. are borne on long spikes and in some species, this spike can reach lengths of up to 3 or 4 metres. Grass trees are long-lived and slow growing and some are estimated to be 350 to 450 years old.
Xanthorrhoea’s provided a range of resources for Aboriginal peoples and early non-Indigenous settlers. The resin was used as a hard-setting glue and waterproofing agent. A range of food was also provided by grass trees such as tender leaf bases, flour ground from the seeds, edible grubs and nectar from the flower stalks.
Grass trees are an important food source for many bird and insect species, including Emus, cockatoos and honeyeaters. Black cockatoos are known to rip open flower spikes seeking out tasty beetle larvae. When in flower, the spear of the plant also attracts many invertebrates and in turn insectivorous species.
This iconic plant is impacted severely by Dieback (Phytophthora cinnomonia). Other threats include land clearing, altered fire regimes, overharvesting of foliage and illegal removal of the plants from their natural habitat for sale as garden plants.