Lemon-Scented Gum (Eucalyptus citriodora)

Tree
E. maculata citriodora.
Common Name Latin Name Plant Family
Lemon-Scented Gum
Eucalyptus citriodora
Myrtaceae

A lemon-scented essential oil is obtained from the leaves[4, 46, 77, 269]. It is used, especially in perfumery but also medicinally[61, 152]. The leaves yield between 0.5 to 2.0% essential oil[240]. This species is a very rich source of citronella, which is much used in the perfumery industry[4, 156]. Some batches of the essential oil contain 98% citronella[4]. Glabrous leaves may contain oil with 65.5% citronellal, 12.2% citronellol, and 3.6% isopulegol; hairy leaves contain more oil with 86.6- 90.1% citronellal, 4.6 – 6.0% citronellol, and 0.7 – 0.8% isopulegol, 1-pinene, b-pinene, and isovaleric aldehyde are also recovered[269].

The leaves and the essential oil are used as an insect repellent[156]. The leaves are also an ingredient of pot-pourri[238].

The bark may contain up to 12% tannin[269].

The wood is good for saw-timber and is used for general construction, poles, railroad ties, and tool handles[61, 269]. Firewood yields run 10 – 21 m3/ha/yr[269]. The hard heavy wood (sp. grav. 0.75 – 1.1) burns steadily and makes a good charcoal with an ash content of 1 – 2%[269].

  • Medicinal Use

    Eucalyptus leaves are a traditional Aboriginal herbal remedy. The essential oil found in the leaves is a powerful antiseptic and is used all over the world for relieving coughs and colds, sore throats and other infections[254]. The essential oil is a common ingredient in many over-the-counter cold remedies[254].An essential oil obtained from the leaves is antibacterial[152]. The essential oil obtained from various species of eucalyptus is a very powerful antiseptic, especially when it is old, because ozone is formed in it on exposure to air. It has a decided disinfectant action, destroying the lower forms of life[4]. The oil can be used externally, applied to cuts, skin infections etc, it can also be inhaled for treating blocked nasal passages, it can be gargled for sore throat and can also be taken internally for a wide range of complaints[4]. Some caution is advised, however, because like all essential oils, it can have a deleterious effect on the body in larger doses[4].

    An oleo- resin is exuded from the tree[238]. It can also be obtained from the tree by making incisions in the trunk[4, 152]. This resin contains tannin and is powerfully astringent, it is used internally in the treatment of diarrhoea and bladder inflammation[4, 152, 238], externally it is applied to cuts etc[4, 152].

  • Edible Use

    Produces a sweet manna-like substance that is scraped off the leaves and eaten[183].

  • Cautionary Notes

    Citronellal, an essential oil found in most Eucalyptus species is reported to be mutagenic when used in isolation[269]. In large doses, oil of eucalyptus, like so many essential oils has caused fatalities from intestinal irritation[269]. Death is reported from ingestion of 4 - 24 ml of essential oils, but recoveries are also reported for the same amount[269]. Symptoms include gastroenteric burning and irritation, nausea, vomiting, diarrhoea, oxygen deficiency, ,weakness, dizziness, stupor, difficult respiration, delirium, paralysis, convulsions, and death, usually due to respiratory failure[269].

Cultivation & Habitat

Seed – surface sow February/March in a sunny position in a greenhouse[11, 78, 134]. Species that come from high altitudes appreciate 6 – 8 weeks cold stratification at 2¡c[200]. Pot up the seedlings into individual pots as soon as the second set of seed leaves has developed, if left longer than this they might not move well. Plant out into their permanent positions in early summer and give them some protection from the cold in their first winter. The seed can also be sown in June, the young trees being planted in their final positions in late spring of the following year. The seed has a long viability[200].
Prefers a sunny position in a moderately fertile well-drained moisture retentive circum-neutral soil[200]. Tolerates poor and dry soils, especially those low in mineral elements[200]. Established plants are drought tolerant[200]. Does not succeed in frost hollows or in windy sites[107]. The plant is said to grow best where the annual rainfall, mostly summer, is 60 to 130cm, with a 5 – 7 month dry season, withstanding high temperatures (29 – 35¡C mean monthly maximum) and light frosts. It succeeds in tropical and subtropical arid to semiarid zones, in infertile clays, laterites, poor and gravelly soils and podzols, preferably well drained[269]. A very fast growing species but it is not very hardy in Britain[166]. It might succeed outdoors in the mildest areas of the country. Eucalyptus species have not adopted a deciduous habit and continue to grow until it is too cold for them to do so. This makes them more susceptible to damage from sudden cold snaps. If temperature fluctuations are more gradual, as in a woodland for example, the plants have the opportunity to stop growing and become dormant, thus making them more cold resistant. A deep mulch around the roots to prevent the soil from freezing also helps the trees to survive cold conditions[200]. The members of this genus are remarkably adaptable however, there can be a dramatic increase in the hardiness of subsequent generations from the seed of survivors growing in temperate zones[200]. Cultivated in warm temperate areas for its essential oil, it thrives in a Mediterranean climate[61, 77]. Eucalyptus monocultures are an environmental disaster, they are voracious, allelopathic and encourage the worst possible attitudes to land use and conservation[200]. The trees cast a very light shade[77]. Flower buds are formed in the summer prior to flowering and seed capsules need at least a further year in which to ripen[11]. Plants are shallow-rooting and, especially in windy areas, should be planted out into their permanent positions when small to ensure that they do not suffer from wind-rock[245]. They strongly resent root disturbance and should be container grown before planting out into their permanent position[11]. The flowers are rich in nectar and are a good bee crop[200].
Australia – Queensland.

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*None of the information on this website qualifies as professional medical advice. Take only what resonates with your heart and use your own personal responsibility for what’s best for you. For more information [brackets] [000], see bibliography.