Hard Yakka! Grass Tree Resin (Xanthorrhoea)

Large resin nodules being melted in a pot, for use in spear making. Photo: © koorihistory.com

The Grass Tree (Xanthorrhoea) is a genus of approximately 30 flowering plants endemic to Australia, which have traditionally been harvested by Koori people for a variety of uses, including the provision of food, drink, and materials utilised in the manufacture of tools and weapons.

As a food source, the Xanthorrhoea provides edible roots and the flower stem is laden with nectar, which can be soaked in water to produce a sweet drink.

The flower stem is also used in conjunction with a hardwood drill for making fire, and may additionally be utilised in the production of a lightweight composite spear. Such a spear would consist of a hardwood shaft inserted into the lightweight grass tree material. This was seen as desirable, considering the overall kit weight that a warrior may traditionally have been required to carry whilst hunting or in transit.

The plant’s trunk provides a highly useful resin, which can be found as exuded nodules attached to the tree’s trunk, or having fallen onto the ground and occasionally buried, either at the base of the plant, or having rolled away if the tree is found on an incline. The resin in most species is ruby red in colour, appearing black and dull on the trunk, unless the resin has been broken (red), or shattered (orange). At least one variety of the plant is known to provide a brilliant yellow resin, resulting in the plant’s Latin name Xanthorrhoea (Yellow flow).

Grass Trees at Bunjilaka Aboriginal Cultural Centre at Melbourne Museum. Photo: © koorihistory.com

As a biomaterial, the resin nodules are harvested and heated to form a type of heat sensitive, reusable glue. This material is somewhat brittle and is often mixed with other materials for binding, such as animal droppings, charcoal, or fur, to provide a more stable cement matrices.

The glue was important in binding axe heads to handles, spear points to their shafts, and generally one material to another. As a resin is also water-proof, which is in contrast to tree sap, the material is also useful in patching damaged water containers and water craft.


One of the many traditional names for the plant, used by some Nunga groups in South Australia is Yacca (alt. Yakka). This name gave rise to the term “Hard Yakka“, in reference to the strenuous work of harvesting the resin as a sifted dust by non-Aboriginal people during the 1920’s, when a number of industries arose from the harvest of the plant’s resin, for use in the production of explosives, varnish, incense, and even an alternative to shellac gramophone records. Unfortunately, non-Aboriginal harvesting methods resulted in the destruction of each plant, and the removal of the plant form from many environments where they were once common.

References:

1. Queensland Times, Ipswich Herald and General Advertiser. 1908, ‘Our Grass-Trees: Their Commercial Value’, 30 Oct, p. 6
2. Daily Commercial News and Shipping List. 1919, ‘Blackboy and its Commercial Uses’, 3 Sep, p. 13
3. The Australasian. 1922, ‘Horticultural Notes’, 9 Sep, p. 9
4. Kalgoorlie Miner. 1926, ‘Blackboy Tanning and By Products: A New Industry’, 13 Jul, p. 3
5. Wildlife and Native Plants Study Group newsletter. 2001, ‘The Grass Tree: Its Uses and Abuses’, Association of Societies for Growing Australian Plants.