Corymbia citriodora

Lemon-Scented Gum

Family: Myrtaceae

An erect tree to a height of 50 metres, forming a lignotuber.

It grows in dry sclerophyll forest and woodland country in several disjunct areas in Queensland, between Cooktown and Gladstone.

It has become a weed elsewhere; naturalised further inland in Queensland, as well as in Western Australia, South Australia, New South Wales and Victoria.

It has smooth bark, ranging from white to cream to pink, slightly mottled and is shed in thin flakes. The junctions where the branches meet the main trunk are typically wrinkled in the axis.

Juvenile leaves are arranged oppositely, whereas the adult leaves are alternately arranged.

Young plants have ovate to lanceolate leaves, to about 20 cm long and to 8 cm wide.

Adult leaves are the same shade of glossy green on both sides, often lemon-scented when crushed, narrow lanceolate to curved, to 25 cm long and to 3 cm wide, tapering to a petiole 10 to 25 mm long. Usually, foliage is narrow and weeping. This, combined with the trunk appearance, is a useful identification feature.

The primary inflorescence of “eucalypts” (Angophora / Corymbia / Eucalyptus) is an umbellaster (an umbel-like cluster of flowers). In this species, they are formed in groups of 3. The umbellasters are clustered into terminal panicles or corymb-like groups, produced beyond the leaves. Each flower is about 2 cm across.

In Corymbia and Eucalyptus, the petals and sepals are fused into the distinctive calyptra / operculum (bud cap) which is shed when the flower opens. The conspicuous stamens give the flowers their appearance; cream in colour. Mature buds are oval to pear-shaped, to 1 cm long and to 7 mm wide with a rounded or beaked operculum. Flowering occurs in most months and peak in Spring. The flowers are white.

The fruit is a woody urn-shaped or barrel-shaped capsule, to 15 mm long and to 15 mm wide, with the valves enclosed in the fruit.

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.

In the garden

A great feature tree that needs significant space. Great for parks, gardens and wide streetscapes. Some landscapers do like them as a feature tree, which can then be lit up at night with garden lighting.

This author has a neighbour’s E. citriodora planted on the boundary of the properties which is now 50 years old. It is unusual in that it has only a straight trunk for the first thirds of its height due to a setback in its early life. They normally grow with a straight trunk for their first two thirds of its height

As well, it has lifted the neighbour’s concrete driveway and may need to be removed soon.

It has a reportedly bad reputation for dropping branches without warning, so caution is advised.

Its flowers are important for honey production and Its volatile oil is an important commodity for cosmetics, medicines, and insect repellents.

It is also popular in horticulture as an ornamental tree and in revegetation projects.

It has become a weed in some areas. This editor is familiar with it growing rampantly along the Georges River at Warwick Farm Racecourse in Sydney, where saplings form thick vegetation. It is also naturalised in WA and Victoria.

Propagation

Eucalyptus can be propagated by seeds which is most common method or grafting.

Seeds available commercially.

Cuttings are difficult to start, but can be used in some species. For further information refer to: http://anpsa.org.au/APOL2007/sep07-s1.html

Other information


Corymbia is one of three similar genera that are commonly referred to as “eucalypts”, the others being Eucalyptus and Angophora.
Refer to these two links for more clarification:
http://anpsa.org.au/eucal1a.html
http://anpsa.org.au/APOL2/jun96-5.html

There is a ‘dwarf’ form which grows to 7 x 3 metres and is marketed as Corymbia citriodora ‘Scentuous’ or ‘Dwarf Pink’.

Corymbia – from the Latin corymbium, meaning “corymb” (a raceme of flowers in which the pedicels of the lower flowers are longer than those of the upper flowers so that the inflorescence has a flat-topped appearance overall (like the shape of a piece of broccoli or cauliflower).

citriodora – Latin – citriodorus meaning lemon-scented.

https://en.wikipedia.org/wiki/Eucalyptus
“Field Guide to Eucalypts Vol 1 South Eastern Australia’ M.I.H.Brooker and D.A.Kleining. Blooming Books.
https://www.anbg.gov.au/gnp/trainees-2016/corymbia-citriodora.html
https://en.wikipedia.org/wiki/Corymbia_citriodora
https://apps.lucidcentral.org/euclid/text/entities/corymbia_citriodora.htm

By Jeff Howes