Native to Queensland – Northern New South Wales, Australia, this medium sized tree grows up to 20m high x 8m wide in the wild, but more commonly to 5m x 3m in cultivated situations. Short trunked with grey-brown bark which sometimes flakes. Ovate, dark green leaves, slightly toothed margins, strongly lemon scented. Flowers are creamy white, 0.5cm across, fluffy white long stamens, in numerous umbel-like clusters at the end of branches in autumn-winter. Named after James Backhouse (1794-1869), a nurseryman, plant collector and Quaker missionary of England visited Australia in 1832-8, making observations of Australian flora and fauna.
Grows in the rainforests between Brisbane and Mackay (thus tropical – semi temperate climate) in semi-shade situations.
Generally easy to grow in any type of well draining soil with rich organic matter, prefers some shade, although can tolerate full sun in cooler climates. Can be frost tender when young but develops to be quite hardy. Propagation is from the very fine seed in spring or semi-ripe summer cuttings (which are slow to form roots) – it is generally slow growing.
Harvesting and Storage
The leaves can be picked when needed from the tree and used fresh or dried. In autumn flowers can be gathered and seeds used when ripe in spring.
Australian Aborigines have long used it as a traditional bushfood and for healing. In the 1990s it became popular as a flavouring in the growing Australian bushfood industry – this has now become its main use as a culinary additive. Fresh or dried leaves can give a lemon flavour to vegetables, soups or casseroles, whole leaves can be stuffed in fish or poultry, in baking (for example adding ground leaves to a shortbread-type biscuit recipe), sauces, desserts and liqueur. It can also be simply used as a herbal tea by steeping the leaves in boiled water.
The lemon odour is used in cosmetics while the essential oil is a strong source of citral which is used in perfumes, soaps, facial creams, deodorants, cosmetics, air fresheners and cleaning products such as washing powders and disinfectants. Simple ways to use this include potpourri/ scented sachets hung in wardrobes or door handles, steeping leaves in boiling water then using as a laundry rinse or even putting a few leaves in the clothes dryer.
Strongly antiviral, can be used by direct application on cold sores. As an infusion, it can be used internally for colds. It is becoming common in aromatherapy. Use of the oil as a treatment for skin lesions caused by molluscum contagiosum virus (MCV), a disease affecting children and immuno-deficient patients, has been investigated. As a natural pest repellent a simple way to use it is to crush a few leaves into a glass jar, cover with a light, unscented oil and let it sit in a sunny position for a few weeks before straining and rubbing on skin to deter mosquitoes and sandflies.
It has two essential oil chemotypes: the most prevalent is citral whereas with a steam distilled oil the yield is typically 90–98%; this is the highest natural source of citral. The second chemotype is citronellal which is uncommon, and is used as an insect repellent.
Elliot, W.R & Jones, D.L. (1982). Encyclopaedia of Australian plants suitable for cultivation. Lothian Publishing Company Pty Ltd: Melbourne
Brown, D. (2002). The RHS new encyclopaedia of herbs and their uses. Dorling Kindersley Limited: London.
Wrigglesworth, J. (-? Month of issue 2011). Simply celestial, New Zealand Gardener.
Wikipedia. Backhousia citriodora. Retrieved Saturday 27th August 2011 from http://en.wikipedia.org/wiki/Backhousia_citriodora.
Australian National Botanic Gardens. Backhousia citriodora. Retrieved Thursday 25th August 2011 from http://www.anbg.gov.au/gnp/gnp14/backhousia-citriodora.html.