Cadaghi: The Rainforest Eucalypt

Skyrail Nature Diary: July 2006

You won’t see any koalas in this Eucalypt, but it’s still worth keeping an eye out for the Cadaghi (Corymbia torelliana), one of the few Eucalypts* to call Australia’s Tropical Rainforests home.

The Cadaghi’s natural territory is the tropical rainforests of Queensland’s north-eastern coastline, stretching between Cooktown and Ingham.

Growing up to 30 metres high and boasting a smooth green trunk, which is sometimes cloaked in a shedding ‘skin’ of dull-grey bark, the Cadaghi is one of the most distinctive looking trees in the forest.

Its trunks’ colouring comes from its chlorophyll content; the trees’ green bark is able conduct photosynthesis, generating carbohydrates for the plant. The Cadaghi has broad leaves, different to traditional Eucalypt leaves, and is heavy with scented, fluffy white blossoms from September to November, although they can be seen as early as July.

The attractive flowers are followed by showers of urn-shaped black nuts, which begin to appear later in the year. The nuts are popular with native bees, who collect the resin to build their hives; they also assist with the dissemination of the nuts throughout the rainforest.

This is a hardy, fast-growing tropical species, which can withstand temperatures as low as -8 degrees Celsius and is resistant to most diseases. Although its nuts are small in comparison to other species of the Corymbia genus, they have a high germination success rate when spread by native bees.

These qualities have seen the Cadaghi extend widely beyond its natural terrain, and today, you can find this rainforest beauty throughout the gardens and forests of south-east Queensland and northern New South Wales.

Not that it is a welcome addition to the plant populations of these communities. The Cadaghi’s spread has become so rampant that some southern local councils, have placed bans on selling or distributing the species.

This is not a problem in its natural, tropical rainforest environment, where habitat, lack of light on the forest floor and the presence of natural threats, including insects, control its population spread.

*NB: The Cadaghi was originally classified in the Eucalyptus genus (named Eucalyptus torelliana), however, it was renamed and reclassified as the Corymbia torelliana in 1995, when the Eucalyptus genus was split into two genera and the Cadaghi became a member of the Corymbia genus. However, it is still commonly referred to as the Rainforest Eucalypt.