The gympie-gympie (Dendrocnide moroides), from the tropical jungles of Australia, is considered to be the most dangerous shrub in the world… and also the most painful.
Its leaves and stems are covered with stinging hairs that cause a reaction that has been compared to “being burnt with hot acid and electrocuted at the same time”. The pain can persist for weeks, even up to 20 years, and has pushed more than one victim to suicide. Dogs and horses that simply brush against the plant have died. Foresters working in the area where the plant is abundant have to wear hazmat suits!
In the unlikely event that you run into a gympie-gympie, get yourself to a hospital, as there is a way to end your suffering (other than putting you down, that is!). Depilatory wax can be used to remove the stinging hairs while wiping the affected area with diluted hydrochloric acid will stop the pain.
Would you be surprised to learn that the gimpy gimpy-belongs to the same family as the nettle (Urticaceae)?