Sydney Blue Gum

The upper trunk, with bark hanging in shreds.

More or less impossible to photograph, this venerable Sydney Blue Gum Eucalyptus saligna stands at the entrance to Ravensbourne National Park in south-east Queensland. It is still here because when loggers arrived in the area in the 19th century, this tree was already old. It was hollow inside, and no use to the loggers. It acts as a multi-storey apartment building for forest animals, their supermarket, as well as being an air purifier and water pump.

 The lower trunk.

High up in the sky bats and bees feed on nectar from its flowers. Down in the trunk termites munch on heart wood. Underground fungi grows on the roots and lives in a symbiotic relationship with insects. Signs of occupancy include claw marks in the trunk, faint trails across the bark and droppings on the ground.