Medicinal plants in Australia, Volume Three: Plants, Potions and Poisons

The Australian flora was largely unknown to the early explorers.  Much of it was simply unfathomable, which made comparisons with more familiar plants somewhat risky. Plants defend themselves against predators, including man.  There are obvious defences such as stinging nettle-like strategies, and burning or blistering latex resins.  Others use different methods to incapacitate.  They include gastrointestinal distress (vomiting or purgation), blindness, neurological disability, or even asphyxia. This clearly illustrates the ingenuity of plant chemistry which, while daunting, has lead to some rather extraordinary discoveries. In the search for food some of the earliest poisonous plants utilised were fish poisons (piscicides). A range of these toxins are found in the Australian flora. A need to find staple dietary items, notably root crops, with low toxicity such as starchy yam tubers was imperative.  Under cultivation, certain species gradually survived a selection process that sought less toxic varieties and high-yielding crop candidates.  Some herbs such as the tomato, were found to yield palatable fruits when they ripened – although not all plants, even if they looked the same, lost their toxicity during the process.

The poisonous potential of numerous plants coincided with a medicinal effect that could not be ignored.  What was the difference between a poisonous, edible or therapeutic effect?  These discoveries were not only pivotal for the remedial use of many plants – they were to open up entire new realms of chemical discovery that has had enormous ramifications for the world of medicine, and the culinary arts.