Corymbia citriodora

Lemon-scented Gum
Scientific classification
Kingdom: Plantae
(unranked): Angiosperms
(unranked): Eudicots
(unranked): Rosids
Order: Myrtales
Family: Myrtaceae
Tribe: Eucalypteae
Genus: Corymbia
Species: C. citriodora
Binomial name
Corymbia citriodora
(Hook.) K.D. Hill & L.A.S.Johnson
C. citriodora, field distribution
Synonyms

Eucalyptus citriodora
E. maculata var. citriodora
E. melissiodora

Corymbia citriodora is a tall tree, growing to 35 metres in height (but sometimes taller), from temperate and tropical north eastern Australia. It is also known as lemon-scented gum, blue spotted gum, lemon eucalyptus and eucalyptus citriodora.

Description

Corymbia citriodora has smooth, pale, uniform or slightly mottled bark, white to coppery in summer, and a conspicuously narrow-leaved crown which smells strongly of lemons. Pear-shaped buds are borne in clusters of three, formed in the corner of leaf and stem junctions, whilst fruit (capsules) are urn-shaped. The bark is smooth for the entire height of the tree, often powdery, shedding in thin curling flakes.[1]

It prefers lighter, slightly acidic loamy soils and occurs in dry sclerophyll forest and woodlands in hilly country. Corymbia citriodora has a lignotuber. Flowering has been recorded in January, April, May, June, July, August, October and December.

Range

Plants of C. citriodora are naturalised in the Darling Range near Mundaring, Western Australia and by planting to suburban New South Wales and Victoria.

An avenue of Lemon-scented Gums in Kings Park, Perth, Western Australia

Kings Park in Perth has a famous, beautiful avenue of this species planted many years ago, but it has spread to become a serious weed there also.[2]

Corymbia citriodora is an important forest tree, in demand for structural timber and for honey production. It also is popular in horticulture both within Australia and overseas. The name Corymbia citriodora comes from the Latin citriodorus, which means lemon-scented.

Essential oil

Eucalyptus citriodora essential oil in clear glass vial

The essential oil of the lemon-scented gum mainly consists of citronellal (80%),[3] produced largely in Brazil and China.[4] While unrefined oil from the lemon eucalyptus tree is used in perfumery, a refined form of this oil is used in insect repellents, especially against mosquitoes. The refined oil's citronellal content is turned into cis- and trans- isomers of p-menthane-3,8-diol (PMD), a process which occurs naturally as the eucalyptus leaves age. This refined oil, which includes related compounds from the essential corymbia citriodora, is known widely by its registered tradename, "Citriodiol", but also by generic names which vary by country or continent: "oil of lemon eucalyptus" or "OLE"(USA); "PMD rich botanic oil" or "PMDRBO"(Europe); "PMD and related oil of lemon eucalyptus compounds" (Canada); Extract of Lemon Eucalyptus (Australia). Pure PMD is synthesized for commercial production from synthetic citronellal. Essential oil refined from the leaves of the tree can contained up to 98% citronella content. The smell of the essential oil can vary, but mostly includes a strong odor compatible alone to citronella oil, with a slight hint of lemon scent.

See also

References

  1. ↑ Factsheet - Corymbia citriodora
  2. ↑ Hussey et al., (1997) Western weeds : a guide to the weeds of Western Australia South Perth, W.A.: Plant Protection Society of W.A. : 1997. ISBN 0-646-32440-3, 1997
  3. ↑ Boland, D.J. et al., Eucalyptus Leaf Oils - Use, Chemistry, Distillation and Marketing, ISBN 0-909605-69-6.
  4. ↑ Lawless, J., The Illustrated Encyclopedia of Essential Oils, ISBN 1-85230-661-0

External links

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