Trees in modern Australia

Trees in modern Australia

Trees in modern Australia

Woody plants, like all organisms, evolve continuously under selective pressure imposed by their environment.

The superficial bark layers are very diverse, as you can see from the living trees of the Arboretum. Australian trees are particularly divergent. Some have smooth bark, some rough. The first Europeans were agog that some bark of some angophoras sloughed off while other species kept their bark firmly attached allowing it to be harvested in single sheets. Bark is used by some indigenous peoples for example for shields, cord, twine and canoes. Cork, aspirin, taxol, cinnamon and quinine are all produced from tree bark.

Fire – in Australia, bark has evolved in part to insulate the cambial cells from fires. Some tree species such as ironbarks are highly resistant to fire. Black Ash from the Blue Mountains is fire resistant while the Blue Mountains Ash is mostly killed by fire and re-seeds vigorously. The specimen (image below) shows damage from a ‘cool’ fire after which the vascular cambium has generated some new tissues.

Extremely cold temperatures often lead to deciduous habits (e.g. the Red Cedar, Toona ciliata). When leaves are lost, cork layers in the bark help protect the trunk from water loss and pathogen attack during winter months.

Invertebrates - the trunk of the Tea Tree in this display (image below) is highly irregular and forms an ideal habitat for many invertebrates. Many Paperbarks (Melaleuca spp.) in Australia also have multi-layered barks suited to insect habitat.

Cross section of Eucalyptus oreades trunkCross section of Red Cedar trunk Cross section of Teatree trunk 

Images: Blue Mountains Ash (Eucalyptus oreades); Red Cedar (Toona ciliata); Tea Tree (Melaleuca sp.)

Back to the top of this page