Xanthorrhoea (Grass tree) is a genus of evergreen plants endemic to Australia with about 30 species, all of which are now protected. Australian Aboriginal people had many traditional uses for Grass trees, which included making tools and weapons, and they provided a minor food source. But they were particularly useful for their resin.
The plant’s trunk provides a resin presented as exuded nodules that are attached to the trunk or found on or buried in the ground at the base of the plant. Generally, the resin is a dull black but when its broken, its colour is ruby red, orange or a brilliant yellow resin, depending on the plant species. The resin also gives off an aroma, which made it useable for incense. The versatility of this resin made it a valuable trading item amongst Aboriginal tribes.
The Grass tree resin holds the leaf base in place and can be found throughout the outer stem, even in really old specimens and when the trunk is broken up, a mass of old resin will be found. This is also why globules of resin form on the outside of the trunk and near the base. Collecting the balls of resin is the best way to extract the resin so as not to harm the plant.
After gathering the resin nodules from the Grass trees, they were heated to form a type of glue. On its own, the resin is quite brittle, so it was usually mixed with charcoal, sand, fur, or animal droppings to strengthen the binding properties and create a more stable cement medium. This glue was essential for attaching axe heads and spear points to handles and shafts, and for many other adhesive purposes. The resin is waterproof, unlike normal tree sap, and thus also effective in repairing water containers and bark canoes.
The resin’s melting point is below the boiling point of water. At first, it liquifies and separates from the woody plant material. After removing the resin part, it is flexible and can be shaped and has a similar consistency to that of blue tack. Once the resin cools, it hardens to form a solid, hard, glassy, and non-sticky material.
The Grass tree was also commonly referred to as the Yacca (Yakka), which was a reference to ‘hard yakka’ meaning strenuous work when harvesting the resin as a sifted dust by Europeans in the early 20th century. During this period, Grass trees were extensively harvested for the production of explosives, wood varnish, stove polish and as a metal coating for tins as well as an alternative to shellac gramophone records.
Regrettably, the European harvesting techniques resulted in the plant’s decimation from many natural environments where they were once prevalent. Although the Grass tree has offered immense value to both the Australian Aborigines and Europeans, its future lies in the hands of the landowners and nature conservationists to preserve the remaining populations. It is a true icon of the Australian bush, providing a unique identity to the region’s landscape.