Seems there are some poisonous plants in Australia that can cause itchy rashes: https://www.firstaidproadelaide.com.au/poisonous-plants-in-australia/ This seems to be our best bet: Rhus or wax tree (Toxicodendron succedaneum) It is a flowering plant species found notably found in Asia, Australia, and New Zealand. Rhus or wax trees can trigger strong allergy reactions, causing itchiness and skin blisters over a week or longer.