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19: Essential-oil plants

Backhousia citriodora F. v. Mueller

MYRTACEAE

Australian lemon myrtle, citron myrtle (En).

Australia (Queensland).

The leaves contain an essential oil with high citral content, which is used in perfumes and soaps and as a flavouring. The oil resembles lemongrass oil, but is said to be of a better quality (e.g. lacking grassy-fatty or harsh notes) and of higher yield. Fresh and dried leaves are used as a flavouring herb in food. The essential oil possesses anti-microbial activity.

Tall shrub or small tree, up to 8 m tall. Leaves opposite, coriaceous; petiole up to 1.5 cm long; blade ovate-lanceolate, 7.5—12.5 cm long. Inflorescence an axillary, umbel-like cyme with a cluster of numerous small flowers at the end of a branch; peduncle 2.5—3 cm long, pedicel longer than 1 cm; calyx tubular, broadly campanulate, 4-lobed; petals 4, shorter than the calyx lobes; pistil with a 2-loculed ovary, each locule with 6—8 pendulous ovules, style filiform, stigma small. Fruit an indehiscent capsule, surrounded by the persistent calyx. Backhousia citriodora occurs in coastal notophyll vine forest. More than 90% of the essential oil from the leaves is citral. The high prices of fresh leaves (US$ 10—15/kg) and the oil (AUS$ 1000/kg) stimulated the start of cultivation of lemon myrtle with commercial potential for flavouring and oil production in Australia. Propagation is possible by cuttings. Commercial cultivation is similar to tea cultivation (yield of fresh leaves about 8 t/ha). The essential oil is extracted from the leaves by steam distillation (oil yield up to 3.8%, citral up to 97.7%). It seems worthwhile to investigate the prospects for Australian lemon myrtle cultivation in South-East Asia, in areas with a climate comparable to Queensland.

[1] Arctander, S., 1960. Perfume and flavor materials of natural origin. Published by the author, Elizabeth, New Jersey, United States. 736 pp.
[3] Bentham, G., 1863–1878. Flora australiensis. 7 Volumes. Reeve, London, United Kingdom.
[11] Groom, N., 1997. The new perfume handbook. 2nd edition. Blackie Academic & Professional, London, United Kingdom. 435 pp.
[12] Guenther, 1949–1952. The essential oils. 6 Vols. D. van Nostrand Co., New York, United States.
[32] Reese, N., 1997. An overview of the Australian Backhousia citriodora industry in December 1996. Internet: Plantwest.

P.C.M. Jansen

Jansen, P.C.M., 1999. Backhousia citriodora F. v. Mueller. In: L.P.A. Oyen and Nguyen Xuan Dung (Editors): Plant Resources of South-East Asia No 19: Essential-oil plants. PROSEA Foundation, Bogor, Indonesia. Database record: prota4u.org/prosea