A team of researchers from the University of Queensland have discovered a previously unidentified neurotoxin that is similar to the venom found in spiders and cone snails.
Unlike its American and European counterparts, being stung by a dendrocnide tree -- which means "stinging tree" -- can cause pain that lasts for days -- or even weeks.
Researchers hope the study, published Wednesday in the Science Advances journal, will help provide new information as to how pain-sensing nerves function, and help in developing painkillers.
"The Australian stinging tree species are particularly notorious for producing [an] excruciatingly painful sting," said Irina Vetter, associate professor at the University of Queensland's Institute for Molecular Bioscience, in a statement.
The dendrocnide plant, commonly referred to by its indigenous name the "Gympie-Gympie" tree, is a rainforest nettle that can be found in eastern parts of Australia.
Like other nettle plants, the trees are covered in fine, needle-like hairs and are known to cause extreme, long-lasting pain.
The fine appendages "look like fine hairs, but actually act like hypodermic needles that inject toxins when they make contact with skin," Vetter said.
Until recently, scientists were unable to figure out which molecules inside the plant caused such severe pain.
Similar plants normally contain small molecules such as histamine, acetylcholine and formic acid, but none of these cause the severe pain elicited by Gympie-Gympie trees, which suggested to researchers that there was an unidentified neurotoxin to be found.
The team discovered a new type of neurotoxin, coined as "gympietides" -- which they named after the plant.
"Gympietides are similar to spider and cone snail toxins in the way they fold into their 3D molecular structures and target the same pain receptors," said Vetter. "This arguably makes the Gympie-Gympie tree a truly 'venomous' plant."
Vetter said that the long-term pain caused by the trees may be explained by the gympietides permanently changing the sodium channels in a person's sensory neurons, as opposed to the plants' fine hairs getting stuck in skin.
"By understanding how this toxin works, we hope to provide better treatment to those who have been stung by the plant, to ease or eliminate the pain," added Vetter.