Trees of Australia the River Red Gum

Eucalyptus camaldulensis or River Red Gum is one of around 800 species in the genus Eucalyptus and has the widest distribution of all. Frederick Dehnhardt, Chief Gardener at the Botanic Gardens in Naples, described the species in 1832 and named it for a private estate garden near the Camaldoli monastery near Naples.

Although the River Red Gum is a plantation species in many parts of the world, it is native to Australia and is found over most of the Australian mainland. It is especially prevalent beside inland water courses and on the floodplains. On the lower levels of the floodplain it is often the only species present. Eucalyptus camaldulensis lines the Murray River for most of its length and is extremely important to the ecological health of the region. It is river flooding which allows survival of the River Red Gum in semi-arid areas. The species also has moderate salt tolerance.

In its natural habitat, Eucalyptus camaldulensis is not often found away from water courses.  It occurs in Queensland and the Northern Territory down to the drier parts of Western Australia, South Australia, New South Wales and Victoria. Depending on its location, the river red gum may be thick-stemmed with widely spreading, somewhat gnarled branches (eg Victoria and South Australia). In more northerly locations, the tree is more slender with a trunk of 11 to 12 metres high. It is very fast growing and can reach 12 to 15 metres in a few years.

In its native locations, the River Red Gum is subject to regular flooding. This provides the sub-soil with water which the trees can utilise during dry periods. Eucalyptus camaldulensis produces seed liberally. These germinate readily after floods and dense stands of young plants may appear. These thin out over time. The River Red Gum relies on regular flooding throughout its life. Indeed if floods are not forthcoming the River Red Gum becomes stressed. The paucity of floods in the Murray-Darling Basin has resulted in a huge decrease in the number of healthy trees.

The tree plays an important part in stabilising river banks and the dense foliage provides shelter and shade in the harsh inland regions of central Australia.  The roots hold the soil together and helps reduce flooding. The mature tree may reach 45 metres tall.  The smooth bark ranges in colour from white to grey and red-brown and is shed in long ribbons except near the base of the bole which will be covered in rough, red-brown bark.  The foliage varies from green to blue green and contains oil-producing glands in the unveined parts of the leaf. The leaves may be very long and narrow.

The River Red Gum is named partly for its brilliant red wood. Depending on the age and weathering, the colour may range from light pink to almost black.  It is rather difficult to work by hand, being somewhat brittle. It is resistant to rot and has been popular over the years for fence posts, sleepers and structural work.  Old, well-seasoned timber is now prized for furniture making and wood turning. The timber is a pale to deep red and is straight grained, strong and durable. When burnt, the charcoal is of a high grade and, in Brazil, is used for iron and steel production.  The trees are popular with apiarists. Honey from Eucalyptus camaldulensis is a clear golden colour with a mild flavour. Eucalyptus camaldulensis is one of the most widely planted eucalypts in the world.

The River Red Gum is a fast-growing tree, which grows straight under good conditions.  In drier periods, the branches may twist and become gnarled.  The River Red Gum is one of the eucalypts known as ‘widow makers’ from their habit of dropping large boughs without warning. Hollows which form in the trunk and branches provide a habitat for birds, carpet pythons, bats and native animals. The Superb Parrot and Regent parrot nest almost exclusively in River Red Gums. These two rare species of parrot are further at risk by the dwindling availability of nesting places.  Branches which fall into the water courses provide refuge and feeding areas for fish and form an important part of river ecosystems.

Eucalyptus camaldulensis was an important tree to the aboriginals who made use of its many medicinal properties. A liniment would be made from the leaves to ease chest or joint pains. Young leaves would be heated to produce vapours which, when inhaled, helped with general well-being.