Part of the Myrtaceae botanical family, the red river gum tree (sometimes called river red gum) is a familiar and iconic tree of the Australian outback. These trees are endemic to Australia, meaning that they have only ever grown naturally there, and nowhere else. There are many tree and plant species like this in Australia, as it is an island with a very specific climate biome.
Red river gum trees are long-lived trees, with an average life expectancy of 500-1000. But beware! These trees are notorious for falling over or losing branches with absolutely no notice, so the locals known to never camp or take a nap under a red river gum tree.
These trees are one of the most widely planted tree species or eucalyptus species of Australia. They are very important to the forest ecology of their growing areas, and they are a crucial source of shade in the extreme temperatures of central Australia.
The river red gum tree is just one of the 101 Types of Trees that we cover in this mammoth article. We discuss other eucalyptus species, we cover fruit trees, coniferous trees, tiny trees, giant trees, and any other type of tree you can think of!
What do River Red Gum Trees Look Like?
The red river gum tree establishes a root system that is slightly different from that of other eucalyptus species, as they exist in waterways and flooding conditions. However, not every season is a wet season, and since they are water-loving species, they must adapt to changing conditions.
Red river gums will grow very deep sinker roots that grow towards the zone of a higher water supply. Their roots have super high rates of hydraulic conductivity (passing water through cell walls through osmosis) which allows them to take in more water in dry seasons.
However, these trees do not produce very wide-spreading lateral roots, which is a lot of the reason why they are so prone to falling over out of nowhere!
Red river gum seedlings will develop aerenchymatous roots in order to cope with full water immersion. This is a specified root tissue that is designed for gas conduction so that a young seedling will be able to access oxygen when it is entirely underwater — as seedlings have not adapted to flooding conditions.
Red river gum trees are medium to large trees, gaining heights anywhere between 20 meters and 45 meters. They are capable of achieving greater heights when they exist in areas that receive more precipitation, or a waterway that does not dry out.
Red river gum trees have thick trunks with branches that split quite low down on a trunk. These thick branches create a very wide and airy canopy, which becomes filled with the large size of leaves that the tree develops — making it into a great shade tree for passers-by.
Red river gum trees produce bark that is usually a smooth white or cream color, with patches of brown, pink, or yellow. This smooth bark will tear off in loose slabs that will slowly decay at the base of the tree.
Juvenile red river gum leaves have a lance shape and are usually 3-7 inches long. Adult leaves will have more of a curved shape and will grow longer than 7 inches long. These evergreen leaves will be either a dull green or gray-green on both sides of the leaf.
How do Red River Gum Trees Reproduce?
Red river gum trees are monoecious, meaning that both male flowers and female flowers will occur on the same tree. Flowers grow in groups of 7-9 on the leaf axils of a peduncle. Flowers are white and will bloom from late spring to mid-summer. Flower buds are almost spherical in shape and are light green to creamy white.
Pollen will be released from a male flower and enter the ovule-producing area of the female flower and fertilize the flower. Otherwise, small mammals, insects, and birds all help with the pollination of red river gum tree flowers.
Once a flower is pollinated, it will produce fruit in the form of a wood capsule. This capsule is actually the fertilized part of the flower that persists on a stem after the flower falls away. The capsule becomes enlarged and dries out.
Once it is fully dried out, triangular valves will open up to disperse yellow cuboid seeds. They are either dispersed by wind, eaten by animals and dispersed, or they are carried along the waterway where the mother tree is growing.
Where do Red River Gum Trees Grow?
The red river gum forest is endemic to mainland Australia. This means that Australia is the only place that red river gum trees have grown naturally. This is often the case with the flora of Australia, as it is an island that has a very specific climate biome.
These trees will grow all over Australia except for southwestern Australia, and the eastern coastal regions of Queensland, New South Wales, and Victoria. There is a very prosperous river red gum forest that grows along the Murray river/Murray Darling basin.
There are plantations of red river gum trees all over the world. They are one of the most widely planted eucalyptus species in the world, and there are plantations in Argentina, Brazil, Burkina Faso, Egypt, Kenya, Morocco, Nigeria, Pakistan, Senegal, Sierra Leone, Spain, Sri Lanka, Sudan, Tanzania, the United States, Uruguay, and Zimbabwe.
When growing in the wild, red river gum trees will only be found growing along flood plains, waterways, and river banks in inland Australia, though they can sometimes be found in creaks of hilly countrysides and on the margins of salt lakes. They are a very important component of riparian communities and have adapted to regular flooding in their natural habitats.
What are the Growing Conditions of Red River Gum Trees?
Red river gum trees prefer to grow in heavy clay-based soils. They are drought intolerant and must have consistently moist soil.
The red river gum tree is completely adapted to flooding conditions. For many parts of the year, the lower part of their trunk will be entirely underwater along watercourses. If they do not grow directly within a watercourse, they will only exist in areas with heavy rainfall.
Plants that grow in Australia don’t really have any other option than to be sun-loving. Luckily for the red river gum tree, they can handle full sun.
How are Red River Gum Trees Used?
Red river gumwood is a hardwood that is named after and known for its brilliant red color. The color can range from very deep red to light pink, depending on the weathering and age of the tree. The wood is slightly brittle and cross-grained — making it difficult to be worked by hand.
Red river gumwood is dense, hard, and resistant to rot, and therefore is used in the manufacturing of fence posts, sleepers, decks, wooden floors, and craft furniture as well.
Red river gumwood is also used as firewood, and for making charcoal as well. The speed at which this tree grows makes it very useful as plantation timber, too.
The main importance that the red river gum tree provides to forest dwellers is habitat. In wet seasons when they are entirely underwater, their roots provide very important breeding habitat for various fish species, like the river blackfish.
This in turn benefits the bird species that exist in the area, and depend on the fish for food. Not only birds, but other roosting animals such as the koala, carpet pythons, and bats rely on the hollows that form in mature trees. The threatened superb parrot only lives in red river gum trees!
Red river gum trees have been planted by beekeepers both in Brazil and Australia, as their fragrant flowers are very attractive to bees. Red river gum flowers add a unique element to honey flavoring as well.