Eucalyptus tereticornis

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

Family: Myrtaceae

A large tree growing to 50 m (and forms a lignotuber) and has a wide distribution, occurring over the widest range of latitudes of any Eucalyptus species, occurring from southern Papua New Guinea at latitude 15°S, to south-eastern Victoria at latitude 38°S.

In NSW, it grows mainly on the coast but extends into the tablelands, with some scattered records in the western slopes. 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.

The trunk is straight, usually unbranched for more than half of the total height of the tree and has a girth of up to 2 m and thereafter, 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.

Juvenile foliage / coppice regrowth is dull bluish-green, egg-shaped or broadly ovate leaves, to 130 mm long and to 80 mm wide. Adult leaves are the same shade of green on both sides, lanceolate to curved, to 220 mm long and to 35 mm wide, tapering at the base to a petiole to 30 mm long.

The flower buds are arranged in leaf axils, usually in groups of seven (umbellasters), nine or eleven, 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 is a capsule 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, in 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.

Propagation

Eucalyptus 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

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

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.

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 – is from the Latin words teres (becoming tereti- in the combined form) meaning “terete” which is “tubular” or “cylindrical” and cornu meaning “horn”, in reference to the tubular horn-shaped operculum / calyptra on the flowers.

Not considered at risk in the wild – very numerous

“Field Guide to Eucalypts Vol 1 South Eastern Australia’ M.I.H.Brooker and D.A.Kleinig. Blooming Books.
https://en.wikipedia.org/wiki/Eucalyptus_tereticornis
https://apps.lucidcentral.org/euclid/text/entities/eucalyptus_tereticornis_subsp._tereticornis.htm

https://en.wikipedia.org/wiki/Eucalyptus
https://plantnet.rbgsyd.nsw.gov.au/cgi-bin/NSWfl.pl?page=nswfl&lvl=sp&name=Eucalyptus~tereticornis

By Jeff Howes, edited Dan Clarke