Money may not grow on trees, but gold might grow in them. Such is the fascinating conclusion of a group of Australian researchers who studied eucalyptus trees in two groves in the country's west and south. The specific locations were chosen because the scientists knew there was gold in the earth below the trees based on previous exploratory drilling, but no mining had actually occurred, eliminating the possibility that gold dust could have been sent airborne and into the trees. What X-ray analysis revealed in the leaves' cells: gold.
LiveScience explains how it works: The roots absorb gold particles and then push them throughout the tree, with the heaviest concentrations settling in the trees' extremities (ie, leaves); the researchers speculate that gold is toxic to the trees, which respond by trying to expel it. The gold particles are minute, about one-tenth the width of a human hair, meaning this is not the kind of gold you can profit off of—directly. Their presence could clue in miners in on the existence of gold far below the surface; National Geographic reports that the trees' roots can extend as many as 130 feet underground in their quest for water. (Read more discoveries stories.)