Written by Sarah Kellett
That’s not paint: this is how the rainbow gum, Eucalyptus deglupta, really looks. Sweeping down the trunks of these trees are streaks of red, green and purple.
As rainbow gums grow, they shed strips of old bark. The new bark underneath is bright green, and the bark changes colour as it gets older. After being red and purple, it becomes brown and is ready to be shed once more.
Not all trees shed their bark as they grow. Ironbarks, which are also in the Eucalyptus family, keep their bark on the outside of the tree. So do oaks.
It is not just funky colour that makes the rainbow gum unusual. “It’s one of four Eucalyptus species that don’t grow in Australia,” says Frank Udovicic, from the Royal Botanic Gardens Melbourne.
“It’s a very tropical species,” he says. “We have samples from across the Philippines, Papua New Guinea and Indonesia.”
The wood of rainbow gums is important to people in these countries for building things and making paper.
“Despite its importance, we don’t know how it fits into the family tree of Eucalyptus,” he says.
Frank hopes to find out how this brightly coloured gum tree is related to other Eucalyptus species, and how it once spread across the islands.
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