River Red Gum

River Red Gum

Common name River Red Gum
Botanical name Eucalyptus camaldulensis subsp. camaldulensis
Family Myrtaceae
Natural range Watercourses of mainland Australia
Mature height 35-45m
Form Varied, often twisted and spreading
Likes Constant access to water. Cannot adapt long-term to flooding or drought
Where to plant Within range of water, allowing for its spreading form
Known for Epic & fatal sudden limb drop

An Australian national treasure

One of Australia’s most prominent and iconic trees, the River Red Gum spreads across much of our mainland and is dominant throughout the Murray-Darling basin.

Twisted, spreading and robust, the River Red Gum can reach a height of 35-45m, and may live for 500-1000 years under ideal conditions. With deep opportunistic roots evolved to seek out water, these trees may be found as the dominant species on many watercourses throughout the country.

How far can River Red Gum roots travel?

In general, the lateral roots of any tree are expected to at least extent to the dripline. For the majority of trees however, it is expected that roots extend 5-7 times the height, in all directions. Ever seen a River Red Gum in the middle of a paddock with no water in sight? Well, the roots of these trees can obviously travel much, much further!

Do River Red Gums grow as a city tree?

This tree is a great choice for cities with rivers and water-courses where the roots can access water, which means they are only suitable for planting along reserves, bicycle trails, adjacent to streams and rivers and within parks. Their size and twisted architecture generally prohibits street-scape planting, but it has been attempted in certain locations throughout Australian cities, to some degree of success.

Can these trees survive without water?

Not for an extended period of time. This makes the River Red Gum a very unsuitable choice for urban planting where soil is of a poor, compacted quality and roots cannot adequately been sent out in search of a water source. In fact a project in the city of Melbourne, Victoria, Australia tried just this, in an urban city-scape planting project, only to find all the newly planted trees soon died from lack of water.

Is sudden limb drop a myth? What causes it?

River Red Gums are also unfortunately notorious for their role in river-side Australian fatalities. Cars and camping tents stand no chance when a huge limb comes crashing down. Sudden limb-drop is so named, because instead of a large branch slowly failing & tearing itself gradually down the trunk of a tree, it releases with a severe “crack” and drops directly to the ground, crushing anything beneath. The three key factors which make sudden limb drop so lethal are:

  • The branch is usually a lateral one (very horizontal)
  • The branch snaps cleanly at a point 1-2 meters away from the main trunk, allowing it to fall directly downwards
  • Eucalyptus trees for the most part grow without lower understory branches, meaning, when a branch comes down, it is almost certain to strike the ground.
Why does sudden limb drop occur?

Experts are still researching this, but we are of the opinion that it is a combination of intense heat followed by a respite, which corresponds to a change in branch Turgor Pressure (water pressure). Others feel there is usually a mild fungal or defect aspect to the branch involved. Other research points to calm periods following high windy weather.

What we all can agree on though is – sudden limb drop almost always occurs on a calm day, just when you least expect it.

Are Eucalyptus trees ‘Widow makers?’

Eucalyptus trees always get a bad rap internationally for sudden limb drop. And while it’s all true, as shedding organisms all trees drop branches. We believe the exponentially high records of limb drop in Eucalypts when compared to North American or European Research, is also partly due to the lack of understory branches in Eucalypts. When an Oak tree drops a branch, it will most likely become caught in the canopy. Whereas those from Gums tend to hit the ground.

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