Eucalyptus tereticornis

Forest Red Gum, Red Irongum, also known as Queensland Blue Gum

Family: Myrtaceae

A large tree growing to 50 m, forming a lignotuber.

This species is has a large natural distribution. In NSW, it grows mainly in the coastal subdivisions but extends into the tablelands, with some scattered records in the western slopes; as far south as around Bega, but then found in Victoria where a disjunct population grows between Lakes Entrance and Traralgon and to the north of Lake Glenmaggie. It is found more or less continuously northwards up the NSW coastal and tablelands into Queensland, where it again extends more or less continuously to the start of the Cape York Peninsula. It is also found in New Guinea.

In NSW, it forms a dominant part of dry sclerophyll forests and woodlands, usually on heavier soils – clay and alluvium. E. tereticornis is one of the key canopy species of the threatened Cumberland Plain Woodlands in Sydney and also forms a dominant species in many other vegetation communities.

The trunk is straight, usually unbranched for more than half of the total height of the tree and can have a trunk of up to 1 metre or more wide. The limbs are unusually steeply inclined for a Eucalyptus species. Bark is shed in irregular sheets, resulting in a smooth trunk surface coloured in patches of white, grey and blue, corresponding to areas that shed their bark at different times. It usually has some plates of brown bark at the base, sometimes short, sometimes extending up several metres in a non-uniform pattern.

Eucalyptus spp. have simple and usually alternate adult leaves with juvenile leaves starting off opposite to alternate (disjunct). In this species, juvenile foliage / coppice regrowth is dull bluish-green, ovate or broadly-ovate leaves, to 130 mm long and to 80 mm wide, blue-green in colour. Adult leaves are the same shade of green to blue-green on both sides, lanceolate to falcate, to 220 mm long and to 35 mm wide, tapering at the base to a petiole to 30 mm long.

The primary inflorescence of “eucalypts” (Angophora / Corymbia / Eucalyptus) is an umbellaster (an umbel-like cluster of flowers). In the flowers of Corymbia and Eucalyptus, the petals and sepals are fused into the distinctive calyptra / operculum (bud cap) which is shed when the flower opens (in some species, 2 bud caps (opercula) are shed). The flowers are conspicuously staminate – where many stamens are basically taking over the role of the petals, all surrounding one central carpel. In this species, the flower buds are arranged in leaf axils, usually in groups of seven, but sometimes 9 to 11, the individual buds on pedicels to 6 mm long.

Mature buds are an elongated-oval shape, to about 15 mm long and to 6 mm wide with a conical to horn-shaped operculum / calyptra that is much longer than the floral cup. Flowering has been recorded in most months and the flowers are white.

The fruit of eucalypts are a woody capsule (commonly called ‘gum nuts’) which come in a wide variety of shapes with the top part having a sunken, flat or raised disc and with the valves inserted, disc-level, exserted to strongly exserted. In this species, the capsules are to 6 mm long and to 8 mm wide with the valves prominently protruding and with a raised disc. Seeds usually black, 0.8–1.5 mm long.

In the garden

A tree commonly planted in bushland revegetation projects. They survive and establish well so long as enough initial watering is given.

It grows very reliably in a garden and remnant trees can be seen on residential yards in western Sydney and other places. They can grow very large and so they are usually not suited for most residential gardens.

(Editor’s note: My grandparents had a large one in the backyard of a quarter-acre block in Cabramatta which provided great shade. It came crashing down, through a fern house, during a severe hailstorm that hit western Sydney in 1990).

They are very suited to a large open lawn, or large landscape gardens. Large trees can have wide trunks and a broad shady canopy.

Has been used for gums, timber, honey, ornamental and medicinal purposes.

A Koala food tree. This species is one of 27 more common Eucalypt and Corymbia plants eaten by them.

Eucalypts can suffer problems from, caterpillars, leaf eating beetles, psyllids and borers to name a few. In undisturbed conditions, the numbers of eucalypt-feeding insects and their predators and parasites are in balance, so that they rarely cause tree death and most trees quickly recover from attack. In a home situation nature can get out of balance.

Has been used for gums, timber, honey, ornamental and medicinal purposes. Likely favoured by flying foxes.


Eucalypts can be propagated by seeds which is most common method or grafting.
Cuttings are difficult to start, but can be used in some species.

Other information

There are four recognised subspecies; however, none of these are recognised currently in NSW:

  • Eucalyptus tereticornis subsp. basaltica has opercula that are not expanded at the base, juvenile leaves that are dull bluish, egg-shaped to round, up to one to two times as long as broad, and pedicels 2.5 to 6 mm long;
  • Eucalyptus tereticornis subsp. mediana has opercula that are not expanded at the base, juvenile leaves that are dull bluish, egg-shaped to round, up to one to two times as long as broad, and pedicels 1 to 3 mm long;
  • Eucalyptus tereticornis subsp. rotunda has opercula that are not expanded at the base, juvenile leaves that are green, round and up to 1.2 times as long as broad;
  • Eucalyptus tereticornis subsp. tereticornis has opercula expanded at the base and juvenile leaves that are lance-shaped to egg-shaped, and two to three times longer than wide.

Regenerates from fire from lignotuber and epicormic shoots as well as from seed bank.

An additional note: NSW calls this tree commonly Forest Red Gum. However, in Queensland, it is known as Queensland Blue Gum. 

Eucalyptus is one of three similar genera that are commonly referred to as “eucalypts”, the others being Corymbia and Angophora.

It is well-known that Eucalyptus is a large and diverse genus. Between 700 and 950 known species are reported, occurring as far north as The Philippines, as well as Indonesia, New Guinea, Timor and Australia. Only 16 species reportedly occur outside Australia. They occur in all Australian states. NSW currently has about 250 species. (See this website for some detailed information: https://apps.lucidcentral.org/euclid/text/intro/learn.htm).

Eucalyptus – from Greek, eu, “well” or “true” and calyptus, referring to the calyptra (καλύπτρo) or operculum, which is a bud cap or covering which covers the developing flowers. The calyptra is a fusion of petals and/or sepals and is shed when the flower opens, leaving a flower with many stamens (staminate) surrounding one female part (carpel).

tereticornis – from the Latin teres (becoming tereti– in the combined form) meaning “terete” which is “tubular” or “cylindrical” and cornu meaning “horn”, in reference to the opercula (calyptra) on the flower buds appearing like tubular horns. 

This species is not considered to be at risk of extinction in the wild. 

Field Guide to Eucalypts – Vol 1 South Eastern Australia. M.I.H.Brooker and D.A.Kleinig. Blooming Books.

EUCLID – Eucalypts of Australia – Centre for Australian National Biodiversity Research               – Eucalyptus tereticornis profile page https://apps.lucidcentral.org/euclid/text/entities/eucalyptus_tereticornis_subsp._tereticornis.htm

NSW Flora Online (PlantNET) – Eucalyptus tereticornis profile page

Wrigley, J.W. & Fagg, M.I. (2001). Australian Native Plants – Propagation, cultivation and use in landscaping. 4th edition. New Holland Publishers, Pty. Ltd. Australia.

By Jeff Howes. Editing and additional text by Dan Clarke.