Sydney red gum fact sheet – kajimbourra | Field of Mars EEC

What are Sydney red gums?

Sydney red gums are medium to tall native trees in the myrtle family, Myrtaceae. Their scientific name is Angophora costata. They are not in the Eucalyptus genus, but they are part of the broader group of trees commonly called eucalypts, along with Eucalyptus and Corymbia.

Sydney red gums are easy to recognise by their spreading, twisted branches and smooth mottled bark, which can be pink, orange, grey or cream. They often grow on Sydney sandstone, including ridges, slopes, gullies and rock crevices. Their leaves grow in opposite pairs, their cream to white flowers appear in clusters in spring and summer, and their woody seed capsules have strong ribs.

A Sydney red gum.

Sydney red gum trunks and branches are smooth and often pink, orange or grey.

Where do Sydney red gums grow?

Sydney red gums grow naturally in eastern Australia. In New South Wales, they occur from the south coast to the north coast and west to the Blue Mountains, with some records extending into Queensland. They are especially familiar in the Sydney region, where they grow in dry sclerophyll forest and woodland on sandstone.

Sydney red gums often grow on deep sandy soils or shallow sandy soils over sandstone. Around Sydney, they can be seen on ridges, slopes, gullies and rocky areas, including Lane Cove National Park and other sandstone bushland near Field of Mars Reserve. Their roots can spread across rock surfaces and help anchor the tree in small cracks and crevices.

Sydney red gums often grow from cracks in sandstone.

How are Sydney red gums used by Aboriginal Peoples?

Sydney red gums are known by the name kajimbourra in some Sydney-area sources. Cultural knowledge about plants belongs to Aboriginal Peoples and should be shared respectfully and with reliable sources.

Some sources record the dark red gum, or kino, from smooth-barked apple (Angophora costata) being mixed with water and used as a medicine for diarrhoea. This use should not be presented as a general use by all Aboriginal Peoples, and students should not collect sap, damage bark or try to make medicines from native plants. Native trees should be observed respectfully and left undisturbed.

The red gum, or kino, of a Sydney red gum oozes from damaged bark.

What animals use Sydney red gums?

Many animals use Sydney red gums for food. Their flowers provide nectar and pollen for insects such as native bees, beetles, flies and butterflies. Nectar-feeding birds such as honeyeaters and rainbow lorikeets visit the flowers, and flying foxes may feed from blossoms at night. Seeds may also be eaten by some parrots and other seed-feeding birds.

Sydney red gums also provide shelter and hunting places. Invertebrates live under loose bark, in leaf litter and on the leaves, while spiders attach webs to branches and bark. Older trees can develop hollows that provide shelter or nesting places for possums, parrots, owls, kookaburras and other hollow-using animals. Fallen branches and logs continue to provide habitat after they reach the ground.

Cream Sydney red gum flowers provide food for insects, flying foxes and nectar-feeding birds.

What is the life cycle of Sydney red gums?

Sydney red gums produce clusters of cream to white flowers in spring and summer. Insects, birds and mammals visit the flowers for nectar or pollen and can help move pollen between flowers. After pollination, woody ribbed seed capsules develop.

When the capsules mature, tiny seeds are released and may fall or be carried a short distance from the parent tree. Seeds germinate when they land in suitable soil with enough light, moisture and space. Young seedlings grow into saplings, and mature Sydney red gums may live for many decades or even hundreds of years if they are protected from clearing, severe damage and repeated disturbance.

Woody ribbed Sydney red gum seed capsules hold and release tiny seeds.

What adaptations do Sydney red gums have to help them survive?

Sydney red gums are well adapted to dry sandstone bushland. Their tough, leathery leaves help reduce water loss, while their spreading roots help them anchor into sandy soils and rocky cracks. Their smooth bark sheds in patches, revealing fresh bark underneath.

Sydney red gums can also recover after fire or damage. New shoots can grow from epicormic buds beneath the bark and from a woody swelling at the base of the tree called a lignotuber. These adaptations help many trees resprout after their canopy has been damaged.

New shoots can grow from epicormic buds after fire or damage.

Why are Sydney red gums important?

Sydney red gums are important habitat trees in Sydney sandstone bushland. Their flowers support pollinators and nectar-feeding animals, while their leaves, bark, logs and leaf litter support insects, spiders, slugs, fungi and other decomposers. Their roots help hold sandy soils and rocky slopes in place.

Large old Sydney red gums are especially valuable because they can form hollows, broad branches, fallen limbs and sheltered spaces used by many animals. Protecting mature trees helps protect whole food webs, from tiny leaf-mining insects to possums, parrots, owls and flying foxes.

Mature Sydney red gums help form tree habitat in Sydney sandstone bushland.

How can you help Sydney red gums?

You can help Sydney red gums by staying on tracks, leaving bark, leaves, flowers, seed capsules and fallen branches where they are, and observing trees without scratching or peeling bark. Bark, leaf litter and logs are important habitat and should be left in the bush.

Protecting bushland also helps young Sydney red gums grow. Join bushcare with trained adults, remove weeds only as part of organised bush regeneration, clean soil from shoes before visiting bushland and learn to identify local native plants. Mature trees should be protected wherever it is safe to do so because hollows can take many years to form.

Observing from tracks helps protect Sydney red gums, roots, bark and seedlings.

Related fact sheets

More plant fact sheets

• Plant fact sheets – Explore more native plant fact sheets from Field of Mars EEC.
• Scribbly gum fact sheet – Learn about another smooth-barked tree of Sydney sandstone bushland.
• Sydney peppermint fact sheet – Compare another eucalypt tree found in local bushland.
• Paper-bark tree fact sheet – Explore a tree that grows along creeklines and wet areas.
• Grass tree fact sheet – Learn about another fire-adapted plant of eucalypt forest.
• Bracken fern fact sheet – Discover an understorey plant that grows below forest trees.

Habitats and ecosystems

• Field of Mars Reserve fact sheet – Learn about the local bushland where many native plants and animals live.
• Eucalypt forest fact sheet – Explore the forest ecosystem where Sydney red gums provide habitat and food.
• Tree habitats fact sheet – Learn how trees provide hollows, bark, branches, flowers and shelter.
• Rock and log habitats fact sheet – Discover how sandstone rocks, fallen branches and logs support small animals.
• Leaf litter habitats fact sheet – Learn about the decomposing leaves and bark beneath forest trees.

Animals that use this habitat

• Insects fact sheet – Discover insects that pollinate flowers, feed on leaves and shelter in bark.
• Rainbow lorikeet fact sheet – Learn about a nectar-feeding bird that visits flowering trees.
• Red wattlebird fact sheet – Explore another bird that feeds from native flowers.
• Grey-headed flying fox fact sheet – Learn about a nocturnal mammal that feeds on blossom and helps pollinate trees.
• Common brushtail possum fact sheet – Find out about a hollow-using mammal that lives in tree habitat.
• Common ringtail possum fact sheet – Learn about a possum that uses shrubs and tree canopies.

Learn with us