Acacias and man - Economic and Cultural Uses

Wattle Day and the Australian Floral Emblem

Traditional Uses

In the areas of natural occurrence of Acacia the indigenous peoples have known and used the plants probably since the beginning of human history. They were widely used in North Africa and India for building construction, furniture and tanning since Neolithic times.³⁶

In Australia, the Aborigines utilised over thirty species as a food source^37,38,43 (including A. aneura, A. victoriae and A. farnesiana). The aborigines gathered the pods and winnowed, parched, ground and cooked the seeds after making a flour. Other seeds, such as those from A. coriacea were eaten green like beans or squeezed with water to make a sweet drink⁴³. Acacias also provided the aborigines with edible gums (particularly from A. loderi), lerps, nectar, ash for mixing with tobacco⁴³ and cooked roots. An infusion of the bark of A. decurrens or A. pycnantha as well as the gum from many species was used medicinally, both by the Aborigines and the early settlers^39,40. As well as providing these foods directly, as noted above, acacias are the hosts to the edible witchetty grub (A. ligulata and A. kempeana) while honey ants are associated with A. aneura⁴³.

Use was made of A. doratoxylon, A. aneura and A. pendula for making utensils, digging sticks, shields, spear-throwers and boomerangs. The bark of some species is toxic, and was used by some aborigines to poison fish in small waterholes by spreading the crushed bark across the water surface. The active agents are probably saponins and tannins. Many species are featured in aboriginal ceremonies and culture.

Other uses of acacia materials include the production of gum arabic, medicines, dyes, lac, soaps, perfumes, fibres and fuel³⁶ and as a source of tannin bark. Acacias were widely used by the aborigines for food and medicines, and the early settlers adopted some of these preparations. In 1871, the New South Wales Medical Gazette⁷⁶ contained a note from a Molong general practitioner citing the use by the settlers of acacia gum dissolved in boiling milk to allievate dysentery and diarrhoea. Other preparations were used for perspiring feet, some affections of the eyes, and as an astringent³⁶. In the early part of the 20th century, intravenous injections of acacia gum were used for the treatment of shock. However, such treatment lead to a disease known as arabinosis and its use was discontinued. A. farnesiana is used in the manufacture of perfumes⁷⁵.

Allan Cunningham records in his Journal of coming upon a settler using the bark of hickory (probably A. implexa or A. penninervis) to tan kangaroo skins. Particularly in Tasmania, Victoria and New South Wales, large quantities of Acacia bark (mostly A. mearnsii) was harvested during the latter part of the 19th century and the first 50 to 60 years of the 20th century, for the leather tanning industry⁴⁴. Extensive plantations, principally A. mearnsii, have also been established in overseas countries for tan bark production. A full account of the wattle bark industry in Australia may be found in the above reference.

In the 1970's to help combat desertification and provide soil stabilization in the dry areas of the sub-Sahara in Africa, Australian acacias from similar climatic zones were introduced. They also acted as windbreaks and provided a ready source of otherwise scarce firewood⁴³. More recently, an Australian Acacia hybrid has been recognised as having a large potential as a human food crop for this region. A number of the more tropical species (including A. cowleana) are being trialled. They are fast growing and high yielding of nutritous seeds which contain crude protein, oil and carbohydrate. The current "bush tucker" industry utilizes acacia seed for a range of products including pasta, ice cream, bread, biscuits, cereals, jams, chutney and muesli bars. The seed adds a nutty flavour to the food. A. victoriae is currently the main species utilized⁴³, and most seed is collected from the wild. As the industry expands harvesting will need to rely more on cultivated crops to prevent the over exploitation of the wild seed source. This species grows under semi-arid and arid conditions. Some Acacia seed, however, is known to be toxic, while some others are palatable only when prepared by special methods.

In times of drought the foliage of many species is used for stock fodder, although it is of low nutritional value and if eaten exclusively causes impaction. But some species, such as A. binervia are poisonous to stock^45.

Blackwood (A. melanoxylon), in particular, was regarded as a valuable timber tree. The main source being northern Tasmania and south-western Victoria where it grows to 35 m tall. It is still used for the production of veneers. Mulga (A. aneura) and gidgee (A. cambagei) have been used, mainly in turnery, for small articles, and many of the more arid species have attractive timbers. A. carneorum is a purplish colour. Brigalow (A. harpophylla) has been used as a construction timber but is not particularly durable. Most have been used for fencing, etc. and in the drier regions large quantities must have been cut for this purpose. Although very hard, many are not very durable and the wood is of small size and poor shape.