ON THE FACE of it, plants may seem innocuous, but some of them can be surprisingly lethal to humans who may come across their path. Because plants cannot run away from their predators, they develop toxicity as a defence. Often shoots are very high in concentration of poison and can be more harmful if consumed. Toxicity usually increases with rising carbon dioxide and plants are more toxic during a drought.
About 1000 species of plants in Australia are known to be toxic to animals and humans and plenty more cause skin and eye irritation, rashes or discomfort. About 10 per cent of plants in Australia even make cyanide. Plants vary from region to region, but no matter where you are you need to know what to keep an eye out for.