Scientists at the Commonwealth Scientific and Industrial Research Organization say eucalyptus, also known as gum trees, in the Western Australian goldfields draw up tiny particles of gold via their roots and it ends up in their leaves and branches.
"The eucalyptus acts as a hydraulic pump -- its roots extend tens of meters into the ground and draw up water containing the gold," CSIRO geochemist Mel Lintern said. "As the gold is likely to be toxic to the plant, it's moved to the leaves and branches where it can be released or shed to the ground."
Don't expect a gold rush, the researchers said; the tree "nuggets" are just one-fifth the diameter of a human hair and invisible to the eye.
Still, they said, the discovery could aid mineral exploration, as trees could indicate gold ore deposits buried deep underground and under sediments that are as much as 60 million years old.
"The leaves could be used in combination with other tools to get an idea of what's happening below the surface without the need to drill," Lintern said. "It could enhance gold exploration in a way that's more targeted and environmentally friendly."