''Backhousia citriodora'' (common names lemon myrtle, lemon scented myrtle, lemon scented ironwood) is a

flowering plant Flowering plants are plants that bear flowers and fruits, and form the clade Angiospermae (), commonly called angiosperms. The term "angiosperm" is derived from the Greek words ('container, vessel') and ('seed'), and refers to those plants th ...

in the family

Myrtaceae Myrtaceae, the myrtle family, is a family of dicotyledonous plants placed within the order Myrtales. Myrtle, pōhutukawa, bay rum tree, clove, guava, acca (feijoa), allspice, and eucalyptus are some notable members of this group. All speci ...

, genus ''Backhousia''. It is endemic to subtropical rainforests of central and south-eastern

Queensland ) , nickname = Sunshine State , image_map = Queensland in Australia.svg , map_caption = Location of Queensland in Australia , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , established_ ...

Australia Australia, officially the Commonwealth of Australia, is a Sovereign state, sovereign country comprising the mainland of the Australia (continent), Australian continent, the island of Tasmania, and numerous List of islands of Australia, sma ...

, with a natural distribution from Mackay to Brisbane. Other common names are sweet verbena tree, sweet verbena myrtle, (lemon scented verbena is another species), and lemon scented backhousia.

Growth

It can reach in height, but is often smaller. The

leaves A leaf (plural, : leaves) is any of the principal appendages of a vascular plant plant stem, stem, usually borne laterally aboveground and specialized for photosynthesis. Leaves are collectively called foliage, as in "autumn foliage", wh ...

are

evergreen In botany, an evergreen is a plant which has foliage that remains green and functional through more than one growing season. This also pertains to plants that retain their foliage only in warm climates, and contrasts with deciduous plants, which ...

, opposite,

lanceolate The following is a list of terms which are used to describe leaf morphology in the description and taxonomy of plants. Leaves may be simple (a single leaf blade or lamina) or compound (with several leaflets). The edge of the leaf may be regular o ...

, long and broad, glossy green, with an entire margin. The

flower A flower, sometimes known as a bloom or blossom, is the reproductive structure found in flowering plants (plants of the division Angiospermae). The biological function of a flower is to facilitate reproduction, usually by providing a mechani ...

s are creamy-white, in diameter, produced in clusters at the ends of the branches from summer through to autumn, after petal fall the calyx is persistent.

Etymology

Lemon myrtle was given the botanical name ''Backhousia citriodora'' in 1853 after the English botanist,

James Backhouse :''See alsfor two other James Backhouse botanists and nursery owners of York.'' James Backhouse (8 July 1794 – 20 January 1869) was a botanist and missionary for the Quaker church in Australia. His son, also James Backhouse (1825–1890), wa ...

. The common name reflects the strong

lemon The lemon (''Citrus limon'') is a species of small evergreen trees in the flowering plant family Rutaceae, native to Asia, primarily Northeast India (Assam), Northern Myanmar or China. The tree's ellipsoidal yellow fruit is used for culin ...

smell of the crushed leaves. "Lemon scented myrtle" was the primary common name until the shortened trade name, "lemon myrtle", was created by the native foods industry to market the leaf for culinary use. Lemon myrtle is now the more common name for the plant and its products. Lemon myrtle is sometimes confused with "lemon ironbark", which is ''

Eucalyptus staigeriana ''Eucalyptus staigeriana'', commonly known as the lemon-scented ironbark, is a species of small ironbark tree that is endemic to the Cape York Peninsula. It has rough ironbark on the trunk and branches, lance-shaped to egg-shaped leaves that sme ...

''.

Essential oils

''Backhousia citriodora'' has two essential oil chemotypes: * The

citral Citral is an acyclic monoterpene aldehyde, and being a monoterpene, it is made of two isoprene units. Citral is a collective term which covers two geometric isomers that have their own separate names; the ''E''-isomer is named geranial (''trans ...

chemotype A chemotype (sometimes chemovar) is a chemically distinct entity in a plant or microorganism, with differences in the composition of the secondary metabolites. Minor genetic and epigenetic changes with little or no effect on morphology or anatomy m ...

is more prevalent and is cultivated in Australia for

flavouring A flavoring (or flavouring), also known as flavor (or flavour) or flavorant, is a food additive used to improve the taste or smell of food. It changes the perceptual impression of food as determined primarily by the chemoreceptors of the gustat ...

and

essential oil An essential oil is a concentrated hydrophobic liquid containing volatile (easily evaporated at normal temperatures) chemical compounds from plants. Essential oils are also known as volatile oils, ethereal oils, aetheroleum, or simply as the o ...

. Citral as an

isolate Isolate may refer to: Arts, entertainment, and media * ''Isolate'' (film), a 2013 Australian film * ''Isolate'' (Circus Maximus album), 2007 * ''Isolate'' (Gary Numan album), 1992 Language * Isolating language, with near-unity morpheme/word ...

in steam distilled lemon myrtle oil is typically 90–98%, and oil yield 1–3% from fresh leaf. It is the highest natural source of citral. * The

citronellal Citronellal or rhodinal ( C10 H18 O) is a monoterpenoid aldehyde, the main component in the mixture of terpenoid chemical compounds that give citronella oil its distinctive lemon scent. Citronellal is a main isolate in distilled oils from the pl ...

chemotype is uncommon, and can be used as an insect repellent.

Uses

Indigenous Australians Indigenous Australians or Australian First Nations are people with familial heritage from, and membership in, the ethnic groups that lived in Australia before British colonisation. They consist of two distinct groups: the Aboriginal peoples ...

have long used lemon myrtle, both in cuisine and as a healing plant. The oil has the highest

purity; typically higher than

lemongrass ''Cymbopogon'', also known as lemongrass, barbed wire grass, silky heads, Cochin grass, Malabar grass, oily heads, citronella grass or fever grass, is a genus of Asian, African, Australian, and tropical island plants in the grass family. Some ...

. It is also considered to have a "cleaner and sweeter" aroma than comparable sources of citral–lemongrass and ''

Litsea cubeba ''Litsea cubeba'', the aromatic litsea or may chang, is an evergreen tree or shrub 5–12 meters high in the family Lauraceae. It is native to Southern Chinese region including Sichuan, Guizhou, Yunnan, Taiwan and Fujian, and Southeast Asian co ...

''.

Culinary

CSIRO ScienceImage 4242 Dried and Crushed Lemon Myrtle Leaves Backhousia citriodora

Lemon myrtle is one of the well known

bushfood Bush tucker, also called bush food, is any food native to Australia and used as sustenance by Indigenous Australians, the Aboriginal and Torres Strait Islander peoples, but it can also describe any native flora or fauna used for culinary or ...

flavours and is sometimes referred to as the "Queen of the lemon herbs". The leaf is often used as dried flakes, or in the form of an encapsulated flavour essence for enhanced shelf-life. It has a range of uses, such as lemon myrtle flakes in

shortbread Shortbread or shortie is a traditional Scottish biscuit usually made from one part white sugar, two parts butter, and three to four parts plain wheat flour. Unlike many other biscuits and baked goods, shortbread does not contain any leavening, ...

; flavouring in

pasta Pasta (, ; ) is a type of food typically made from an unleavened dough of wheat flour mixed with water or eggs, and formed into sheets or other shapes, then cooked by boiling or baking. Rice flour, or legumes such as beans or lentils, are som ...

; whole leaf with baked

fish Fish are aquatic, craniate, gill-bearing animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish as well as various extinct related groups. Approximately 95% of li ...

; infused in

macadamia ''Macadamia'' is a genus of four species of trees in the flowering plant family Proteaceae. They are indigenous to Australia, native to northeastern New South Wales and central and southeastern Queensland specifically. Two species of the genus ...

or vegetable oils; and made into

tea Tea is an aromatic beverage prepared by pouring hot or boiling water over cured or fresh leaves of '' Camellia sinensis'', an evergreen shrub native to East Asia which probably originated in the borderlands of southwestern China and northe ...

, including tea blends. It can also be used as a lemon flavour replacement in

milk Milk is a white liquid food produced by the mammary glands of mammals. It is the primary source of nutrition for young mammals (including breastfed human infants) before they are able to digestion, digest solid food. Immune factors and immune ...

-based foods, such as

cheesecake Cheesecake is a sweet dessert consisting of one or more layers. The main, and thickest, layer consists of a mixture of a soft, fresh cheese (typically cottage cheese, cream cheese or ricotta), eggs, and sugar. If there is a bottom layer, it m ...

, lemon flavoured

ice-cream Ice cream is a sweetened frozen food typically eaten as a snack or dessert. It may be made from milk or cream and is flavoured with a sweetener, either sugar or an alternative, and a spice, such as cocoa or vanilla, or with fruit such as str ...

and

sorbet Sorbet (), also called "water ice", is a frozen dessert made using ice combined with fruit juice, fruit purée, wine, liqueur, honey, etc. Generally sorbets do not contain dairy ingredients, while sherbets do. Etymology The word "sorbet" e ...

without the curdling problem associated with

fruit

acidity In computer science, ACID ( atomicity, consistency, isolation, durability) is a set of properties of database transactions intended to guarantee data validity despite errors, power failures, and other mishaps. In the context of databases, a sequ ...

. The dried leaf has

free radical A daughter category of ''Ageing'', this category deals only with the biological aspects of ageing. Ageing Ailments of unknown cause Biogerontology Biological processes Causes of death Cellular processes Gerontology Life extension Metabo ...

scavenging ability.

Antimicrobial

Lemon myrtle

possesses

antimicrobial An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals ar ...

properties; however the undiluted essential oil is toxic to human cells ''

in vitro ''In vitro'' (meaning in glass, or ''in the glass'') studies are performed with microorganisms, cells, or biological molecules outside their normal biological context. Colloquially called "test-tube experiments", these studies in biology an ...

''. When diluted to approximately 1%, absorption through the skin and subsequent damage is thought to be minimal. Lemon myrtle oil has a high

Rideal–Walker coefficient The Rideal–Walker coefficient, now only of historical interest, is a figure expressing the disinfecting power of any disinfectant. It is the ratio of the dilution of the disinfectant that kills a microorganism to the dilution of phenol that kill ...

, a measure of antimicrobial potency. Use of lemon myrtle oil as a treatment for skin lesions caused by

molluscum contagiosum virus ''Molluscum contagiosum virus'' (MCV) is a species of DNA virus, DNA poxvirus that causes the human skin infection molluscum contagiosum. Molluscum contagiosum affects about 200,000 people a year, about 1% of all diagnosed skin diseases. Diagnosi ...

(MCV), a disease affecting children and immuno-compromised patients, has been investigated. Nine of sixteen patients who were treated with 10% strength lemon myrtle oil showed a significant improvement, compared to none in the control group. A study in 2003 which investigated the effectiveness of different preparations of lemon myrtle against bacteria and fungi concluded that the plant had potential as an

antiseptic An antiseptic (from Greek ἀντί ''anti'', "against" and σηπτικός ''sēptikos'', "putrefactive") is an antimicrobial substance or compound that is applied to living tissue/skin to reduce the possibility of infection, sepsis, or putre ...

or as a surface disinfectant, or as an anti-microbial food additive. The oil is a popular ingredient in health care and cleaning products, especially soaps, lotions, skin-whitening preparations and shampoos.

Cultivation

Lemon myrtle is a cultivated ornamental plant. It can be grown from tropical to warm temperate climates, and may handle cooler districts provided it can be protected from frost when young. In cultivation it rarely exceeds about and usually has a dense canopy. The principal attraction to gardeners is the lemon smell which perfumes both the leaves and flowers of the tree. Lemon myrtle is a hardy plant which tolerates all but the poorest drained soils. It can be slow growing but responds well to slow release fertilisers. Seedling lemon myrtle go through a shrubby, slow juvenile growth stage, before developing a dominant trunk. Lemon myrtle can also be propagated from cutting, but is slow to strike. A study into the plant growing

adventitious roots Important structures in plant development are buds, shoots, roots, leaves, and flowers; plants produce these tissues and structures throughout their life from meristems located at the tips of organs, or between mature tissues. Thus, a living plant ...

found that "actively growing axillary buds, wide stems and mature leaves" are good indicators that a cutting will take root successfully and survive. A further study on temperature recommended glasshouses for growing cuttings throughout the year. Growing cuttings from mature trees bypasses the shrubby juvenile stage. Cutting propagation is also used to provide a consistent product in commercial production. In plantation cultivation the tree is typically maintained as a shrub by regular harvesting from the top and sides. Mechanical harvesting is used in commercial plantations. It is important to retain some lower branches when pruning for plant health. The harvested leaves are dried for leaf

spice A spice is a seed, fruit, root, bark, or other plant substance primarily used for flavoring or coloring food. Spices are distinguished from herbs, which are the leaves, flowers, or stems of plants used for flavoring or as a garnish. Spices a ...

, or distilled for the essential oil. The majority of commercial lemon myrtle is grown in Queensland and the north coast of

New South Wales ) , nickname = , image_map = New South Wales in Australia.svg , map_caption = Location of New South Wales in AustraliaCoordinates: , subdivision_type = Country , subdivision_name = Australia , established_title = Before federation , es ...

, Australia. A 2009 study has suggested that drying lemon myrtle leaves at higher temperatures improves the citral content of the dried leaves, but discolours the leaves more.

Myrtle rust

A significant fungal pathogen, myrtle rust (''

Uredo rangelii ''Austropuccinia psidii'', commonly known as myrtle rust, guava rust, or ʻōhiʻa rust; is a rust (a type of plant pathogen) native to South America that affects plants in the family Myrtaceae. It is a member of the fungal complex called the ...

'') was detected in lemon myrtle plantations in January 2011. Myrtle rust severely damages new growth and threatens lemon myrtle production. Controls are being developed.

Lemon myrtle history

* Pre-1788 – Aboriginal people use ''B.citriodora'' for medicine and flavouring. * 1853 – Scientifically named ''Backhousia citriodora'' by botanist,

Ferdinand von Mueller Baron Sir Ferdinand Jacob Heinrich von Mueller, (german: Müller; 30 June 1825 – 10 October 1896) was a German-Australian physician, geographer, and most notably, a botanist. He was appointed government botanist for the then colony of Vict ...

, with the genus named after friend, James Backhouse,

quaker Quakers are people who belong to a historically Protestant Christian set of Christian denomination, denominations known formally as the Religious Society of Friends. Members of these movements ("theFriends") are generally united by a belie ...

missionary and botanist. * 1888 – Bertram isolates

from ''B.citriodora'' oil, and Messrs. , Dresden, write about the

as having “...probably a future.” * 1900s–1920s – ''B.citriodora'' distilled on a small-scale commercial basis around Eumundi, Queensland. * 1920s – Discovery of

qualities of steam-distilled ''B.citriodora'' oil, by

A. R. Penfold Arthur de Ramon Penfold (4 August 1890 – 16 June 1980) was an Australian chemist and museum director. He is best known today for his work on the essential oils of Australian plants, especially tea tree oil. Early life Penfold was born in Sydne ...

and R.Grant, Technological Museum,

Sydney Sydney ( ) is the capital city of the state of New South Wales, and the most populous city in both Australia and Oceania. Located on Australia's east coast, the metropolis surrounds Sydney Harbour and extends about towards the Blue Mountain ...

. * 1940s –

Tarax Tarax is an Australian brand of soft drink, available in several flavours, and sold in cans and bottles. The name ''Tarax'', itself was the brand-name of an independent soft drink manufacturer and bottler, from the state of Victoria History Ge ...

Co. use ''B.citriodora'' oil as a lemon

during

World War II World War II or the Second World War, often abbreviated as WWII or WW2, was a world war that lasted from 1939 to 1945. It involved the vast majority of the world's countries—including all of the great powers—forming two opposin ...

. * 1950s – Some production of oil carried out in the Maryborough and Miriam Vale areas from bush stands by JR Archibold, but the small industry falls into decline. * 1989 – ''B.citriodora'' investigated as a potential leaf spice and commercial crop by

Peter Hardwick Peter Hardwick (born 1958) is an Australian food horticulturist and environmentalist, recognized as an early pioneer of the Australian bushfood industry. He publicly challenged the established belief that native Australian food plants were not suit ...

, Wilderness Foods Pty Ltd. The company commissions Dr Ian Southwell, The Essential Oils Unit, Wollongbar Agricultural Institute, to analyse ''B.citriodora'' selections using

gas chromatography Gas chromatography (GC) is a common type of chromatography used in analytical chemistry for separating and analyzing compounds that can be vaporized without decomposition. Typical uses of GC include testing the purity of a particular substance, ...

. * 1990 – Restaurants and food manufacturers supplied with dried ''B.citriodora'' leaf by

Vic Cherikoff Vic Cherikoff is regarded as an authority on Australian native foods and its associated industry, having been involved in the selection and commercialization of many of the 35 or so indigenous Australian plant foods now in the market place. He ...

, Bush Tucker Supply Pty Ltd, produced by Russel and Sharon Costin, Limpinwood Gardens. * 1991 – ''B.citriodora'' plantation established by Dennis Archer and Rosemary Cullen-Archer, Toona Essential Oils Pty Ltd, ; and subsequent commercial supply of plantation produced ''B.citriodora'' oil in 1993. * 1997 – Large-scale plantations of ''B.citriodora'' established in north Queensland, by Australian Native Lemon Myrtle Ltd. * Late 1990s – ''B.citriodora'' begins to be supplied internationally for a range of

cosmetic Cosmetic may refer to: *Cosmetics, or make-up, substances to enhance the beauty of the human body, apart from simple cleaning *Cosmetic, an adjective describing beauty, aesthetics, or appearance, especially concerning the human body *Cosmetic, a t ...

and

anti-microbial An antimicrobial is an agent that kills microorganisms or stops their growth. Antimicrobial medicines can be grouped according to the microorganisms they act primarily against. For example, antibiotics are used against bacteria, and antifungals a ...

products. Agronomic production of ''B.citriodora'' starts to exceed demand. * 2001 – Standards for Oil of ''B.citriodora'' established by The Essential Oils Unit, Wollongbar, and

Standards Australia Standards Australia is a standards organisation established in 1922 and is recognised through a Memorandum of Understanding (MoU) with the Australian government as the primary non-government standards development body in Australia. It is a co ...

.Standards Australia, "Australia Standard, Oil of ''Backhousia citriodora'', citral type (lemon myrtle oil)", AS 4941-2001. * 2004 – Monograph published on ''B.citriodora'' by Toona Essential Oils pty Ltd. * 2010 – Lemon myrtle sells out in London after

Jamie Oliver James Trevor Oliver MBE OSI (born 27 May 1975) is an English chef, restaurateur and cookbook author. He is known for his casual approach to cuisine, which has led him to front numerous television shows and open many restaurants. Oliver reache ...

describes it as " pukka" on his TV show.

References

External links

Australian Bushfood and Native Medicine Forum

Broad range of lemon myrtle products and recipes

Lemon Myrtle
from Vic Cherikoff {{Taxonbar, from=Q2708073 citriodora Flora of Queensland Myrtales of Australia Trees of Australia Bushfood Crops originating from Australia Medicinal plants of Australia Australian cuisine Essential oils Taxa named by Ferdinand von Mueller