Common name: Lemon Myrtle

Lemon Myrtle is an ornamental and essential-oil-yielding tree native to Australia, with its range confined to pockets of subtropical forest along the continent's east coast.

It grows at a slow to moderate rate, in native forests to heights of up to 25 m (65 ft), with a straight, slim trunk up to 0.25 m (10 in) in diameter and clear of branches for more than half the tree height. On open sites, it is typically 5 to 10 m (15 to 30 ft) tall, with a low-branching habit and a densely leafy pyramidal crown. The bark is thin, grey or light brown, rough and fissured, sometimes flaking.

Leaves are lance-shaped, 7 to 12 cm (2.8 to 4.7 in) long, lime green when young, changing to dark green, and with a strong lemon fragrance when crushed. They remain on the tree throughout the year.

Small creamy-white flowers with long stamens bloom in profuse clusters from spring to early summer, almost hiding the green foliage from view. Brown, woody seed capsules follow them with small seeds inside. The seeds are released when the capsules fall to the ground and split on impact.

Peacehaven Botanic Gardens, Toowoomba, Australia

Flower cluster​

Material uses

Essential oil - Steam distillation of the leaves yields a pale yellow, lemon-lime-scented essential oil, used in a wide range of products, including food, perfumes, medicines, cleaning, and toiletry goods.

Around 8,000 kg of fresh leaves are harvested per hectare per year in commercial plantations; with an oil content of 0.7% to 1%, yields are 56 to 80 kg of oil per hectare (50 to 70 lb per acre). Because the oil is corrosive to plastic, it must be stored and transported in glass or stainless steel containers.

Natural fragrance - Used as a fragrance component in perfumes.

Natural disinfectant - Its antimicrobial activity also sees it used as a disinfectant in cleaning products.

Natural insect repellent - Lemon Myrtle oil has one of the highest citronella contents of any essential oil, probably second only to Lemon Eucalyptus (Corymbia citriodora), giving it insect-repellent properties.

Hardwood - The wood is heavy, averaging about 960 kg per cubic meter (60 lb per cubic ft), with pale pink- to red-brown heartwood, though logs are too small to be sawn into lumber. Its natural resistance to rot, decay, and wood-boring insects is not well researched.

Woodturning - Roundwood, when available, is used for turnery.

Tool handles - Also used for tool handles.

Wood craft - Also used for woodcraft more generally.

Edible uses

Natural flavouring - The leaves are steam-distilled to yield an essential oil used as a flavouring in food.

Natural food preservative - The oil's antimicrobial and antifungal activity has also generated interest in its potential as a natural food preservative.

Culinary herb - The leaves are also used fresh or dried as a culinary herb, to add flavour to sweet and savoury dishes, oils, syrups, and preserves.

Tea - Also commonly brewed into a citrus-flavoured tea.

Environmental uses

Fragrant plant - The leaves release a strong lemon aroma when crushed.

Hedge plant - This fragrant plant can be cultivated as a hedge, with pruning needed to maintain the desired height and shape.

Shade or privacy screen - Also grown as a privacy screen.

Bee forage - Honeybees can be observed working vigorously on the flowers, though their importance to honey production is unknown.

Climate

Lemon Myrtle grows naturally in moderately humid subtropical and tropical mid-elevation climates, generally best in frost-free areas with average annual lows of 9 to 19°C, average annual highs of 19 to 30°C, annual rainfall of 700 to 2000 mm and a dry season of 5 months or less.

Growing

New plants are usually started from semi-hardwood cuttings. It performs best on rich, moist, free-draining soil of a mildly acid to neutral nature, generally with a pH of 5.5 to 7.0 and on sites with partial sun exposure. It has poor tolerance to alkaline, slow-draining or waterlogged soils.

Problem features

There does not appear to be any record of it as a weed or as having naturalised anywhere in the world.

Books

• Arctander, S. 1960, Perfume and flavor materials of natural origin, Elizabeth, New Jersey

• Barwick, M., et al. 2004, Tropical & subtropical trees : a worldwide encyclopaedic guide, Thames and Hudson, London

• Church, G. & Greenfield, P. 2002, Trees and shrubs for fragrance, David Bateman, Auckland, New Zealand

• Groom, N. 1997, The new perfume handbook, 2nd ed., Blackie Academic & Professional, London

• Lake, M. 2015, Australian rainforest woods : characteristics, uses and identification, CSIRO Publishing, Collingwood, Victoria

• Leech, M. 2013, Bee Friendly: A planting guide for European honeybees and Australian native pollinators, Rural Industries Research and Development Corporation (RIRDC), Canberra, Australian Capital Territory

• Macmillan, H. F. 1943, Tropical planting and gardening : with special reference to Ceylon, 5th ed, Macmillan Publishing, London

• Oakman, H. 1995, Harry Oakman's what flowers when : the complete guide to flowering times in tropical and subtropical gardens, University of Queensland Press, St. Lucia, Queensland

• Peate, N. & Macdonald, G. & Talbot, A. 2006, Grow what where : over 3,000 Australian native plants for every situation, special use and problem area, 3rd ed., Bloomings Books, Richmond, Victoria, Australia

• Salvin, S. 2008, The new crop industries handbook : native foods, Rural Industries Research and Development Corporation (RIRDC), Barton, Australian Capital Territory

• Seidemann, J. 2005, World spice plants: economic usage botany taxonomy, Springer-Verlag, Berlin

• Woodward, Penny 1997, Pest-repellent plants, Hyland House, South Melbourne