Botanical Name: Backhousia citriodora
Origin: bushy Queensland rainforest tree to about 8m
Leaves: dark green, strong lemon-scent, to 100 mm long.
Flower: prolific, small white flowers on the ends of the branches, in large bunches.
Variations: It has two relatives that are also high in essential oils: anis myrtle (Backhousia anisata) and cinnamon myrtle (Backhousia myrtifolia). The genus Backhousia is named after the British botanist, James Backhouse (1794 – 1869).
Use: ornamental garden plant in southern QLD. Plantation plant for essential oil.
Essential Oil: (typically, 4 to 5%) that is made up almost totally of terpenoid aldehyds: citral (90 to 95% (compared to lemon = 3%)), neral and geranial. Trace constituents are myrcene, linalool, citronellal, cyclocitral and methyl-heptenone. Oil extracted by steam distillation.
Aroma: refreshing, lemon-like, strong.
Culinary use: leaves, fresh or dried as tea, or spice in fish dishes, bread, chicken, rice dishes and sauces.
Cultivation: common garden plant in Brisbane, and about a million have been planted commercially for their lemon oil content. The essential ingredient is Citral, which accounts for over 90% of the plants essential oil, compared to about 3% in lemon oil. The oil is extracted by steam distillation.
Usage: leaves are used fresh or dried & ground and have a lemon & lime oil flavour. They can be used with baked fish, to make a lemon tea, breads and cheesecakes etc., chicken and rice dishes, curries, sauces. Also used in soaps, creams and cosmetics.
Caution: oil is very strong and needs dilution.

Links:
About Lemon Myrtle Essential Oil (CSIRO)
Some Lemon Myrtle Recipes
Growing Lemon Myrtle