In a number of other societies poisonous plants were occasionally cooked and prepared in special ways to make them into edible foods. The Dyirbal people, however, used complicated methods of removing the poison from several different plants on a regular basis. One of these poisonous plant food sources was the fruit of the cycad Lepidozamia hopei .
Even though these plants contain such powerful poisons, the method of turning them into food has been practised by the Aborigines for many centuries. Horsfall (1987) showed that toxic food plants were probably used by Aborigines of the Russell River district about 2000 years ago.
In his 19th century observations, R.A. Johnstone, mentioned the processing of the fruit of a zamia palm which he described as bearing a 'very handsome cone-shaped fruit'. He noted how the roasted, cracked and pounded kernels were soaked in a dilly-bag ( Janjuu ) in a running stream. ( Johnstone 1904:Feb.20 )
Pedley (1992) p33
She often brought work she had to do for the tribe with her, such as yellow walnuts and zamia nuts, which she ground on a flat stone with deep grooves cut in it, then washed in running water for a long time, using bark covering a big knot or bulge in a tree as a dish. The result was a coarse flour something like cornflower but not so fine. It was baked on flat stones before being eaten.
Short (1988) p.58
The fruit of the zamia provided an important staple food usually during April, while the black bean, Castanospermum australe ( ganyjuu ), was available most of the year (it was stored in pits at the wet-season camps). Also requiring elaborate processing to remove a poison, ganyjuu provided a staple food resource for the Ngadjon.
In 1901 Roth noted how the people of Atherton prepared the ganyjuu :
....the kernels are commenced to be baked about sunrise, the covering leaves and earth being removed about midday. They are then cut up into very fine chips with a sharp shell, etc., and about sunset are put into a lawyer cane dilly-bag, through which the creek (i.e. running) water is made to percolate, and there it remains until the following morning, when it is ready to eat. ( Actually, ganyjuu requires 3-4 days leaching - Ed. )
as quoted by Pedley (1992) p.33
(Photograph courtesy of Cairns Historical Society) Using a snail shell to grate black bean seeds ( ganyjuu ) for food.
The main meal of the day was when the hunting and gathering parties returned... While small food items were cooked quickly at the edge of the campfire, large game or fish were cooked in an earth oven ...this method is very similar to the Maori hungi. ..eels were smoked on a grid of green saplings.
Toohey (1990) p.11
Overall the procedures involved in the processing of toxic seeds, which were a main source of starch and carbohydrate, were cooking, which tends to be steaming (earth oven) but may be roasting in a fire, then ground or sliced in the case of ganyjuu , then leached 1-4 days depending on the species.