Lavender (Lavandula) is a genus of forty-seven known species of flowering shrubs in the mint family, Lamiaceae. It is a medicinal lavender, which is an evergreen perennial plant. It is native to the Old World and is found in Cape Verde and the Canary Islands, and from Europe across to Northern and Eastern Africa, the Mediterranean, Southwest Asia to India. These fragrant, evergreen, aromatic shrubs of the mint or labiate family form compact and regular clumps. The lower part of the stem is woody, while the upper part is green herbaceous morphology.
Generally, lavender has linear or lanceolate leaves with curled edges and a highly branched fibrous root system. It grows on well-drained, fertile, and lime soils in full sun with wind protection. It can be fertilized with manure or chemical fertilizers. However, horticultural care should be taken not to acidify the soil or introduce too much nitrogen, as this causes an excessive gain in the green parts with a simultaneous reduction in the inflorescence. There are around twenty-five species. Moreover, most species grow twenty-four to thirty-six inches high and a similar width. They are valued for their attractive lacy, fragrant, usually grayish foliage.
The small mauve-purple or bluish-purple flowers emerge from between bracts in erect, short spikes held on stalks above the foliage, mostly in spring. These plants prefer full sun and fertile, well-drained soil. They will thrive in both acid and alkaline soils. The woodier species such as Lavandula dentata are excellent as low hedges, and a light trim after blooming keeps them neat. The hardiness varies with the species, although most are moderately frost hardy if the growth is well-ripened by warm fall or autumn weather. This lavender may be propagated generatively from seeds or vegetatively from soft and hardwood cuttings, or through plant tissue culture. It needs regular pruning to stimulate plant growth and to promote flowering. The flowers should be collected before opening, dried in bundles in shaded and well-ventilated places.
Several of which are cultivated in Southern Europe and elsewhere for the perfume industry. This is because there are oil glands at the bases of the flowers that produce the pungent oil of lavender, obtained commercially by hydro-distillation from Lavandula angustifolia and Lavandula stoechas.
Lavamdula angustifolia or also known as Lavandula officinalis, L. spica, and L. vera. It is commonly lavender. It is a dense, bushy subshrub that is not native to England despite its English common name but comes from the Mediterranean region of Southern Europe. It grows to about three feet tall though usually lower with narrow, furry gray leaves. It is grown mainly for the long-stemmed heads of purple, scented flowers that appear in summer and through the warm months.
Among all species, it is the easiest dried for lavender sachets, potpourri, and the like. Lacandula angustifolia makes an attractive low hedge and can be trimmed after flowering. There are several selected cultivars, of which ‘Munstead’ and the dwarf ‘Hidcote’ are outstanding. ‘Alba’ grows to two feet with three feet spread. It has yellowish-gray bark on its woody stems, pale gray-green foliage, and white flowers in whorls. ‘Jean Davis’ grows to fifteen to eighteen inches and has attractive blue-green foliage and tall pinkish-white flowers.
Lavandula dentata is densely packed, soft spikes of mauve-blue flowers remain on this shrub from the fall through to late spring in warm climates. A native of the western Mediterranean and Atlantic islands, its gray-green aromatic leaves are fern-like with blunt teeth or lobes. It grows to a height and spread of three to four feet. This marginally frost-hardy species is resistant to dry conditions adaptable to most soils and Is often used as an edging plant to soften the harsh lines of paving.
English lavender called lavandin, which is scientifically referred to as Lavandula x intermedia is naturally occurring and cultivated hybrids between Lavandula angustifolia and Lavandula latifolia show considerable variation in plant size and flower form. Very few will exceed three feet tall, but generally, they are something of a catch-all group. The variety ‘Provence’ has green foliage and small-bracted spikes of mauve-pink flowers. Furthermore, there is a spike lavender, which is called Lavandula latifolia that is very like Lavandula angustifolia that is differing in its slightly wider leaves, but narrower floral bracts. A rounded clump rarely reaches three feet high and wide. It has gray stems and foliage that are downy and fragrant. In the summer, they will produce heavily scented and light purple flower spikes. Its compact form makes it an ideal specimen for containers and dwarf hedges.
In addition, there is a hybrid lavender that originated in Australia, which is known as Lavandula ‘Sidonie’ whose seed parent is reportedly Lavandula pinnata. It makes a soft and mound-like shrub of loose form with grayish leaves that are deeply divided into narrow lobes. It produces a long succession of flower spikes that are held above the foliage on a long but rather weak stalk. The flower stalks bear strongly scented flowers that are the rich blue color from the late winter to early fall. It is categorized as a vigorous grower, but it is rather frost tender.
A Spanish lavender, which is usually called French lavender that is native to the western Mediterranean is the frost-hardy species among the lavender. It is scientifically known as Lavandula stoechas which is the most striking in flower or all lavenders. It is a small and neat shrub that is twenty to thirty inches high with pine-scented and narrow silvery green leaves with inward-curling edges. This lavender is covered with spikes of deep purple flowers in late spring and summer. Several bracts at the apex of each spike are elongated into pinkish-purple ‘rabbit ears’ of varying size. ‘Merle’ is a compact bush with long-eared and magenta-purple flowerheads. ‘Marshwood’ is a particularly heavy flowering and long-blooming cultivar.
Besides, Lavandula stoechas subspecies lusitanica has very narrow leaves and dark purple flowers with paler ‘rabbit ear’ bracts. A species of lavender from Spain, North Africa, and the Balkans, Lavandula stoechas subspecies pedunculata is found growing eighteen to twenty-four inches tall. It has flower stalks that grow up to two to three inches. This species has greenish foliage throughout the growing stage. The unique trait of this species is that the flower spikes are plump and pale green after the flowers have dropped. Then, Lavandula stoechas subspecies luisieri is lavender that is native to Portugal, which is an upright bush with green rather than silver-gray foliage and large purple flower spikes.
A green lavender (Lavandula viridis) that originated from Spain, Portugal, as well as Madeira is an upright and bushy shrub is known as the most unusual lavender. This is because it has green leaves and the palest green flowers among all species under the same family. The flowers have emerged from the short-stemmed dense spikes from mid- to late-summer. ‘Pippa White’ has flowerheads with large bracts that can grow to a height of thirty inches.
There is a sub-shrubby species that is very like Lavandula angustifolia, which is commonly known as spike lavender and scientifically known as Lavandula latifolia. It is differing in its slightly wider leaves, but narrower flower bracts. A rounded clump rarely reaching three feet high and wide, its gray stems and foliage are downy and fragrant. The heavily scented, light purple flowers appear in spikes in the summer. Its compact form makes it an ideal specimen for containers and dwarf hedges.
Applications and uses
Most of us have grown up with the scent of lavender in our homes and this essential oil continues to be as popular today as it has been down the centuries past. The most valuable substance isolated from lavender is an essential oil that is found in oil glands, which is located on the surface of the calyx, in the furrows between fine hairs. Lavender is famous due to the presence of the lavender oil that is commonly used in fragrance aromatherapy, which is one of the more popular complementary and alternative medicine as well as an herbal treatment. Subsequently, the material used for herbal purposes includes lavender flowers (Lavandula flores) containing three percent essential oil, anthocyanins, phytosterols, sugars, minerals, and tannins. Furthermore, aromatherapy is one of the more popular complementary and alternative medicine modalities in the United Kingdom. It is thought to be therapeutically effective due to both the psychological effect of the odor and the physiological effects of the inhaled volatile compounds, where the latter effects are believed to act via the limbic system, particularly the amygdala and hippocampus.
Next, the qualitative and quantitative composition of the essential oil of lavender is variable and depends on genotype, growing location, climatic conditions, propagation, and morphological features. Lavender oil is created by steam distillation of the flowering heads and foliage. The lavender oil contains over three hundred chemical compounds that have dominant components such as linalool, linalyl acetate, terpinene-4-ol, acetate lavandulol, ocimene, and cineole. Lavender oil is commonly used in clinical treatment. Essential oils are believed to be safe with few known side effects in treating people who are suffering from transiently poor sleep, a step away from insomnia.
Additionally, lavender oil is extremely effective when combined with massage has the potential to be of significant benefit to patients, visitors, and workers in many health care settings. This results in the reduction in the perception of pain and the need for conventional analgesics in both adults and children. It has been reported to have antispasmodic actions with relaxant activities in smooth muscle contribute to the relaxant effects in humans. Then, lavender oil also functions as an ergogenic aid in sports training. There is a caution should be exercised in patients with known allergy or hypersensitivity to lavender. The people with allergy to lavender may experience mild local skin reactions after topical use of lavender oil.
Besides, the lavender essential oil has good antioxidative and antimicrobial activities that have a significant positive effect on the digestive and nervous systems. The active compounds present in herbs exhibit multidirectional phytotherapeutic activities and are used in the treatment of gastrointestinal, cardiovascular, respiratory, and urinary infections as well as in chronic diseases of children and elderly people. Lavender extract prevents dementia and may inhibit the growth of cancer cells, while lavender hydrolate is recommended for the treatment of skin problems and burns. Then, lavender oil has been used in wound healing during World War I.
Besides its application in herbal treatment, lavender is widely used in the cosmetic, perfume, food, and aromatherapeutic industries. The Romans used lavender as a bath additive, and in the Middle Ages, it was one of the most valuable essential oil plants used in perfume and soap making. It was also used as a food additive and laxative. Today, pure oil is most often used in aromatherapy or incorporated into soaps and other products as a pleasant fragrance or as an antimicrobial agent. Traditionally, linen bags containing lavender flowers were commonly placed under pillows for their alleged soporific properties. Lavender vapor has also been shown to inhibit the mycelial growth of Aspergillus fumigatus. However, the effect only lasted until the vapor was removed and the does require was comparable to that of tea tree oil, but higher than that of lemongrass, cinnamon bark, and thyme oils.
On top of that, lavender is widely used in household chemicals. It is present in toilet water, eau de cologne, lotions, and after-shaves, which give them a strong top note while imparting a scent of freshness and purity to household cleaning preparations. In culinary, it is grown as a condiment and used in salads and dressings. Flowers yield abundant nectar from which bees make high-quality honey. Monofloral honey is produced primarily around the Mediterranean and is marketed worldwide as a premium product. The flowers of the lavender can be candied and are sometimes used as cake decorations. The lavender flavors baked goods and desserts especially when it is paired with chocolate. In addition, lavender flowers are famous for blending with black, green, or herbal teas apart from being processed into lavender sugar.
References：
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Cavanagh, H. M., & Wilkinson, J. M. (2005). Lavender essential oil: a review. Australian infection control, 10(1), 35-37.
Fismer, K. L., & Pilkington, K. (2012). Lavender and sleep: A systematic review of the evidence. European Journal of Integrative Medicine, 4(4), e436-e447.
Prusinowska, R., & Śmigielski, K. B. (2014). Composition, biological properties and therapeutic effects of lavender L). A review. Herba polonica, 60(2), 56-66.
Shahdadi, H., Bahador, R. S., Eteghadi, A., & Boraiinejad, S. (2017). Lavender a plant for medical uses: a literature review. Indian J. Public Heal. Res. Dev, 8, 328-332.
Malloggi, E., Menicucci, D., Cesari, V., Frumento, S., Gemignani, A., & Bertoli, A. (2021). Lavender aromatherapy: A systematic review from essential oil quality and administration methods to cognitive enhancing effects. Applied Psychology: Health and Well‐Being.
