Lavandula is a genus of 39 species of flowering plants in the mint family, Lamiaceae.
It is native to the Old World and is found from Cape Verde and the Canary Islands, southern
Europe across to northern and eastern Africa, the Mediterranean, southwest Asia to southeast
India.
Many members of the genus are cultivated extensively in temperate climates as ornamental plants
for garden and landscape use, for use as culinary herbs, and also commercially for the extraction
of essential oils.
The most widely cultivated species, Lavandula angustifolia is often referred to as lavender,
and there is a colour named for the shade of the flowers of this species.
Description The genus includes annual or short-lived herbaceous
perennial plants, and suffrutescent perennials, subshrubs or small shrubs.
Leaf shape is diverse across the genus.
They are simple in some commonly cultivated species; in others they are pinnately toothed,
or pinnate, sometimes multiple pinnate and dissected.
In most species the leaves are covered in fine hairs or indumentum, which normally contain
the essential oils.
Flowers are borne in whorls, held on spikes rising above the foliage, the spikes being
branched in some species.
Some species produce coloured bracts at the apices.
The flowers may be blue, violet or lilac in the wild species, occasionally blackish purple
or yellowish.
The calyx is tubular.
The corolla is also tubular, usually with five lobes.
Nomenclature and taxonomy L. stoechas, L. pedunculata and L. dentata
were known in Roman times.
From the Middle Ages onwards, the European species were considered two separate groups
or genera, Stoechas and Lavandula, until Linnaeus combined them.
He only recognised five species in Species Plantarum, L. multifida and L. dentata and
L. stoechas and L. spica from Southern Europe.
L. pedunculata was included within L. stoechas.
By 1790 L. pinnata and L. carnosa were recognised.
The latter was subsequently transferred to Anisochilus.
By 1826 Frédéric Charles Jean Gingins de la Sarraz listed 12 species in three sections,
and by 1848 eighteen species were known.
One of the first modern major classifications was that of Dorothy Chaytor in 1937 at Kew.
The six sections she proposed for 28 species still left many intermediates that could not
easily be assigned.
Her sections included Stoechas, Spica, Subnudae, Pterostoechas, Chaetostachys and Dentatae.
However all the major cultivated and commercial forms resided in the Stoechas and Spica sections.
There were four species within Stoechas while Spica had three, L. latifolia and L. lanata).
She believed that the garden varieties were hybrids between true lavender L. angustifolia
and spike lavender.
More recently work has been done by Upson and Andrews, and currently Lavandula is considered
to have three subgenera.
Subgenus Lavandula is mainly of woody shrubs with entire leaves.
It contains the principal species grown as ornamental plants and for oils.
They are found across the Mediterranean region to northeast Africa and western Arabia.
Subgenus Fabricia consists of shrubs and herbs, and it has a wide distribution from the Atlantic
to India.
It contains some ornamental plants.
Subgenus Sabaudia constitutes two species in the southwest Arabian peninsula and Eritrea,
which are rather distinct from the other species, and are sometimes placed in their own genus
Sabaudia.
In addition there are numerous hybrids and cultivars in commercial and horticultural
usage.
Etymology The English word lavender is generally thought
to be derived from Old French lavandre, ultimately from the Latin lavare, referring to the use
of infusions of the plants.
The botanic name Lavandula as used by Linnaeus is considered to be derived from this and
other European vernacular names for the plants.
However it is suggested that this explanation may be apocryphal, and that the name may actually
be derived from Latin livere, "blueish".
The names widely used for some of the species, "English lavender", "French lavender" and
"Spanish lavender" are all imprecisely applied.
"English lavender" is commonly used for L. angustifolia, though some references say the
proper term is "Old English Lavender".
The name "French lavender" may be used to refer to either L. stoechas or to L. dentata.
"Spanish lavender" may be used to refer to L. stoechas, L. lanata or L. dentata.
Cultivation
The most common form in cultivation is the common or English lavender Lavandula angustifolia.
A wide range of cultivars can be found.
Other commonly grown ornamental species are L. stoechas, L. dentata, and L. multifida.
Because the cultivated forms are planted in gardens worldwide, they are occasionally found
growing wild as garden escapes, well beyond their natural range.
Commonly such adventitious establishment is apparently harmless at best, but in some cases
Lavandula species have become invasive; for example, in Australia Lavandula stoechas has
become a cause for concern; it occurs widely throughout the continent, and has been declared
a noxious weed in Victoria since 1920.
It also is regarded as a weed in parts of Spain.
Lavenders flourish best in dry, well-drained, sandy or gravelly soils in full sun.
All types need little or no fertilizer and good air circulation.
In areas of high humidity, root rot due to fungus infection can be a problem.
Organic mulches can trap moisture around the plants' bases, encouraging root rot.
Gravelly materials such as crushed rocks give better results.
Lavender oil
Commercially the plant is grown mainly for the production of essential oil of lavender.
This has antiseptic and anti-inflammatory properties.
These extracts are also used as fragrances for bath products.
English lavender yields an essential oil with sweet overtones, and can be used in balms,
salves, perfumes, cosmetics, and topical applications.
Lavandin, Lavandula × intermedia, yields a similar essential oil, but with higher levels
of terpenes including camphor, which add a sharper overtone to the fragrance.
The lavandins Lavandula × intermedia are a class of hybrids of L. angustifolia and
L. latifolia.
The lavandins are widely cultivated for commercial use, since their flowers tend to be bigger
than those of English lavender and the plants tend to be easier to harvest, but lavandin
oil is regarded by some to be of a lower quality than that of English lavender, with a perfume
less sweet.
Culinary use
It is grown as a condiment and used in salads and dressings.
Flowers yield abundant nectar from which bees make a high-quality honey.
Monofloral honey is produced primarily around the Mediterranean, and is marketed worldwide
as a premium product.
Flowers can be candied and are sometimes used as cake decorations.
Lavender flavours baked goods and desserts, and is also used to make "lavender sugar".
Lavender flowers are occasionally blended with black, green, or herbal teas.
Though it has many other traditional uses in southern France, lavender is not used in
traditional southern French cooking.
It does not appear at all in the best-known compendium of Provençal cooking, J.-B. Reboul's
Cuisinière Provençale In the 1970s, a herb blend called herbes de Provence usually including
lavender was invented by spice wholesalers, and lavender has more recently become popular
in cookery.
Lavender lends a floral and slightly sweet flavour to most dishes, and is sometimes paired
with sheep's-milk and goat's-milk cheeses.
For most cooking applications the dried buds, which are also referred to as flowers, are
used.
Some chefs experiment with the leaves but only the buds contain the essential oil of
lavender, from which the scent and flavour of lavender are derived.
In the United States, both lavender syrup and dried lavender buds are used to make lavender
scones and marshmallows.
Medical uses
The essential oil was used in hospitals during World War I.
Lavender is used extensively with herbs and aromatherapy.
Infusions are believed to soothe insect bites, burns, and headaches.
Bunches of lavender repel insects.
In pillows, lavender seeds and flowers aid sleep and relaxation.
An infusion of flowerheads added to a cup of boiling water is used to soothe and relax
at bedtime.
Lavender oil is used to treat acne when diluted 1:10 with water, rosewater, or witch hazel;
it also treats skin burns and inflammatory conditions.
A study published in 2010 investigated anxiolytic effects and influence on sleep quality.
Lavender oil with a high percentage of linalool and linalyl acetate, in the form of capsules,
was generally well tolerated.
It showed meaningful efficacy in alleviating anxiety and related sleep disturbances.
Lavender oil is approved for use as an anxiolytic in Germany under the name Lasea.
A survey paper on lavender and the nervous system published in 2013 states that, "there
is growing evidence suggesting that lavender oil may be an effective medicament in treatment
of several neurological disorders."
Lavender may be very effective with wounds; however, Lavender Honey, instead of lavender
essential oil has the best effects of uninfected wounds.
Health precautions The U.S. National Institutes of Health states
that lavender is considered likely safe in food amounts and possibly safe in medicinal
amounts.
NIH does not recommend the use of lavender while pregnant or breast-feeding because of
lack of knowledge of its effects.
It recommends caution if young boys use lavender oil because of possible hormonal effects leading
to gynecomastia, and states that lavender can cause skin irritation.
Gynecomastia
A study was published in 2007 on the use of lavender and gynecomastia in prepubescent
boys.
Three young boys developed gynecomastia while using products containing lavender.
The boys stopped using the products, and the gynecomastia went away.
The researchers found that lavender and tea tree oil can cause estrogenic and antiandrogenic
activities in cell cultures, and the paper states that "repeated topical exposure to
lavender and tea tree oils probably caused prepubertal gynecomastia in these boys."
After the study was published The New England Journal of Medicine received letters disputing
the paper's findings, and the authors were allowed to respond.
The Aromatherapy Trade Council of the UK and the Australian Tea Tree Association have published
rebuttals.
The Aromatherapy Trade Council's rebuttal states among other things that:
It isn't likely that there would be sufficient lavender in the personal care products used
in the three cases to cause an endocrine effect.
The gyncomastia might have come from another source.
The rebuttal states that although endocrine disruptors such as medications, oral contraceptives,
marijuana and soy products were considered other disruptors such as organochloride pesticides,
PCBs, polychlorinated dioxins, alkyl phenols, pthalates, and parabens were not.
The paper states that it is not clear that the lavender and/or tea tree oil caused the
gynecomastia but say that, "other components in these products may also possess endocrine-disrupting
activity that contributed to the gynecomastia, but those components were not tested because
we chose to evaluate only the component that was found in all the products used by the
patients and a chemically similar component that was found in some of the products."
The rebuttal points out that lavender is in widespread use saying, "considering that some
200 tonnes per annum are produced of both lavender and tea tree oil, that most of this
goes into personal care products, and that very little of the evidence presented for
these 3 cases is convincing, the press reports of caution are premature."
The Australian Tea Tree Industry Association rebuttal states that various other plants
have estrogen inducing effects in essential oil form, including, "soy, hops, garbanzo
beans, red clover, lentils, flaxseed, sunflower seeds, alfalfa sprouts, liquorice, and ginseng."
A study published in 2010 from the Research Institute for Fragrance Materials did not
find estrogenic activity from lavender oil in laboratory animals.
A newer version of the paper became available in 2013.
Skin Irritant In 2004 a study was published which found
that, "lavender oil is cytotoxic to human skin cells in vitro".
On the other hand, aromatherapist Robert Tisserand points out in a blog post that: "Any type
of in vitro test is only suggestive of a possible effect.
You can never assume that the same effect will take place in the living body."
A review published in 2005 on lavender essential oil states that, "Lavender is traditionally
regarded as a 'safe' oil and, although it was recently reported that lavender oil, and
its major constituent linalyl acetate, are toxic to human skin cells in vitro, contact
dermatitis to lavender oil appears to occur at only a very low frequency."
Photosensitivity A study was published in 2007 which looked
a the relationship between various fragrances and photosensitivity.
The study stated that lavender is known "to elicit cutaneous phototoxic reactions".
However, the research did not find that lavender induced photohaemolysis.
Other uses
Flower spikes are used for dried flower arrangements.
The fragrant, pale purple flowers and flower buds are used in potpourris.
Lavender is also used extensively as herbal filler inside sachets used to freshen linens.
Dried and sealed in pouches, lavender flowers are placed among stored items of clothing
to give a fresh fragrance and to deter moths.
Dried lavender flowers have become recently popular for wedding confetti.
Lavender is also popular in scented waters and sachets.
In history and culture The ancient Greeks called the lavender herb
nardus, after the Syrian city of Naarda.
It was also commonly called nard.
The species originally grown was L. stoechas.
Lavender was one of the holy herbs used in the biblical Temple to prepare the holy essence,
and nard is mentioned in the Song of Solomon
nard and saffron, calamus and cinnamon,
with every kind of incense tree, with myrrh and aloes,
and all the finest spices.
During Roman times, flowers were sold for 100 denarii per pound, which was about the
same as a month's wages for a farm laborer, or fifty haircuts from the local barber.
Its late Latin name was lavandārius, from lavanda, from the verb lavāre.
The Greeks discovered early on that lavender if crushed and treated correctly would release
a relaxing fume when burned.
In medieval times powdered lavender was used as a condiment.
Taxonomic table
This is based on the classification of Upson and Andrews, 2004.
Gallery
See also Lavender oil
Lavender References
Sources Chaytor D A.
A taxonomic study of the genus Lavandula. 1937
Upson T, Andrews S.
The Genus Lavandula.
Royal Botanic Gardens, Kew 2004 United States Department of Agriculture GRIN:
Lavandula External links
Medicinal use from University of Maryland Medical Center