Money really does grow on trees - at least in Australia.

Scientists have found gold in the leaves of eucalyptus trees.

The particles are much too small to be seen with the naked eye but have been detected using a type of x-ray that is especially good at picking up trace amounts of metals and minerals.

However, gold hunters shouldn't start felling gum trees in the hope of becoming rich.

Study leader Mel Lintern told the Brisbane Times: 'If you had 500 eucalyptus trees growing over a gold deposit, they would only have enough gold in there to make a wedding ring.'

The real value of the study is that nature's own version of gold leaf could provide mine companies with an inexpensive and environmentally friendly indicator of where to drill test sites.

The study by the Commonwealth Scientific and Industrial Research Organisation in Western Australia showed levels of the precious metal were highest in trees growing directly over gold seams, one of which was 115 feet down.

The researchers believe the gold was taken up by the trees' extensive roots from while scouring for water during times of drought.

It was then transported through the tree to the leaves, where concentrations are higher than in the twigs, trunk or surface soil.

The researchers said: 'Gold is probably toxic to plants and is moved to extremities, such as leaves in order to reduce deleterious biochemical reactions.'

Writing in the journal Nature Communications, they said it was the first time that gold had been found naturally incorporated into a living thing.