Chrysopogon zizanioides, commonly known as vetiver and khus, is a perennial bunchgrass of the family Poaceae.
Vetiver is most closely related to sorghum while sharing many morphological characteristics with other fragrant grasses, such as lemongrass (Cymbopogon citratus), citronella (Cymbopogon nardus, C. winterianus), and palmarosa (Cymbopogon martinii).
Etymology
Vetiver is derived from the Tamil () meaning 'root that is dug up', via French . In Northern India it is also called ('grass', not to be confused with , which refers to poppy seed).
History
During the reign of Harshavardhan, Kannauj became the biggest centre for aromatic trade and for the first time, a vetiver tax was introduced.
Starting in 1990, the World Bank promoted use of vetiver grass by farmers for soil and water management in countries like India, Nepal, Thailand, and Nigeria.
Description
Vetiver grows to high and forms clumps as wide, and under favorable conditions, the erect culms can reach in height. The stems are tall and the leaves are long, thin, and rather rigid. The flowers are brownish-purple. Unlike most grasses, which form horizontally, spreading mat-like root systems, vetiver's roots grow downward in depth.
The vetiver bunch grass has a gregarious habit and grows in tufts. Shoots growing from the underground crown make the plant frost and wildfire resistant, and allow it to survive heavy grazing pressure. The leaves can become up to long and wide. The panicles are long and have whorled, long branches. The major vetiver producers include Haiti, India, Indonesia, and Réunion (part of the Mascarene Islands, east of Madagascar).
The most commonly used commercial genotypes of vetiver are sterile, and because vetiver propagates itself by small offsets instead of underground stolons, these genotypes are noninvasive and can easily be controlled by cultivation of the soil at the boundary of the hedge. However, care must be taken, because fertile genotypes of vetiver have become invasive.
Almost all vetiver grown worldwide is vegetatively propagated; bioengineering has shown them as essentially the same nonfertile cultigen by DNA profiling. In the United States the cultivar is named 'Sunshine,' after the town of Sunshine, Louisiana.
Uses
Vetiver grass is grown for many purposes. The plant helps to stabilise soil and protects it against erosion, but it can also protect fields against pests and weeds. Vetiver has favourable qualities for animal feed. From the roots, oil is extracted and used for cosmetics, aromatherapy, herbal skincare and ayurvedic soap. Its fibrous properties make it useful for handicrafts, ropes and more.
Skin care
Vetiver has been used to produce perfumes, creams and soaps. It is used for its antiseptic properties to treat acne and sores.
Soil and water conservation
Erosion control
thumb|left|Vetiver roots for sale
Several aspects of vetiver make it an excellent erosion control plant in warmer climates. Vetiver's roots grow almost exclusively downward, , which is deeper than some tree roots.
The Vetiver System, a technology of soil conservation and water quality management, is based on the use of the vetiver plant.
Runoff mitigation and water conservation
The close-growing culms help to block surface water runoff . It slows the water flow and increases the amount absorbed by the soil (infiltration). It can withstand water velocity up to . In the Philippines and India, the roots are woven to make fragrant-smelling fans called "sandal root fans".
Vetiver's essential oil has anti-fungal properties against Rhizoctonia solani.
As a mulch, vetiver is used for weed control in coffee, cocoa and tea plantations. It builds a barrier in the form of a thick mat. When the mulch breaks down, soil organic matter is built up and additional crop nutrients become available.
Vetiver as a termite repellent
Vetiver extracts can repel termites. However, vetiver grass alone, unlike its extracts, cannot be used to repel termites. Unless the roots are damaged, the anti-termite chemicals, such as nootkatone, are not released.
Animal feed
The leaves of vetiver are a useful byproduct to feed cattle, goats, sheep and horses. The nutritional content depends on season, growth stage and soil fertility.
Perfumery and aromatherapy
thumb|Vetiver (Vetiveria zizanioides= Chrysopogon zizanioides) essential oil in a clear glass vial
Vetiver is mainly cultivated for the fragrant essential oil distilled from its roots. In Cuddalore, farmers grow of vetiver for oil extraction with help of marudhamalai groups. In perfumery, the older French spelling, vetyver, is often used. Worldwide production is estimated at about 250 tonnes per annum. Vetiver is used widely in perfumes for its excellent fixative properties. It is contained in 90% of Western perfumes. Vetiver is a more common ingredient in fragrances for men; some notable examples include Dior's Eau Sauvage, Guerlain Vétiver, M. Vétiver by Une Nuit à Bali, Zizan by Ormonde Jayne, Vétiver by L'Occitane en Provence, Encre Noire by Lalique, and Vetiver Root by Korres.
Indonesia, China, and Haiti are major producers. Vetiver processing was introduced to Haiti in the 1940s by Frenchman Lucien Ganot. In 1958, Franck Léger established a plant on the grounds of his father Demetrius Léger's alcohol distillery. The plant was taken over in 1984 by Franck's son, Pierre Léger, who expanded the size of the plant to 44 atmospheric stills, each built to handle one metric ton of vetiver roots. Total production increased in ten years from 20 to 60 tonnes annually, making it the largest producer in the world. The plant extracts vetiver oil by steam distillation. Another major operation in the field is the one owned by the Boucard family. Réunion is considered to produce the highest quality vetiver oil, called "bourbon vetiver", with the next favorable being Haiti and then Java.
The United States, Europe, India, and Japan are the main consumers.
Essential oil
Composition
Vetiver oil, or khus oil, is a complex oil, containing over 150 identified components, typically:
{|
|-
|benzoic acid || furfurol
|-
|vetivene || vetivenyl vetivenate
|-
|terpinen-4-ol || 5-epiprezizane
|-
|khusimene || α-muurolene
|-
|khusimone || Calacorene
|-
|β-humulene || α-longipinene
|-
|γ-selinene || δ-selinene
|-
|δ-cadinene || valencene
|-
|calarene,-gurjunene || α-amorphene
|-
|epizizanal || 3-epizizanol
|-
|khusimol || Iso-khusimol
|-
|valerenol || β-vetivone
|-
|α-vetivone || vetivazulene
|}
<gallery>
File:Alpha-Vetivone.svg|Structure of α-vetivone, the main fragrant component of the oil of vetiver
File:Khusimol.svg|Structure of khusimol, another fragrant component of the oil of vetiver
File:Beta-Vetivone.svg|Structure of β-vetivone, another fragrant component of the oil of vetiver
</gallery>
The oil is amber brown and viscous. Its odor is described as deep, sweet, woody, smoky, earthy, amber and balsam. The best quality oil is obtained from 18- to 24-month-old roots. The roots are dug up, cleaned, and then dried. Before distillation, the roots are chopped and soaked in water. The distillation process can take up to 24 hours. After the distillate separates into the essential oil and hydrosol, the oil is skimmed off and allowed to age for a few months to allow some undesirable notes formed during distillation to dissipate. Like patchouli and sandalwood essential oils, vetiver's odor develops and improves with aging. The oil's characteristics can vary significantly depending on where the grass is grown and the climate and soil conditions. The oil distilled in Haiti and Réunion has a more floral quality and is considered of higher quality than the smokier oil from Java. In north India, oil is distilled from wild-growing vetiver. This oil is known as khus or khas, and in India is considered superior to the oil obtained from the cultivated variety. It is rarely found in commerce outside of India, as most of it is consumed within the country.
Medicine
Vetiver has been used in traditional medicine in South Asia (India, Pakistan, Sri Lanka), Southeast Asia (Malaysia, Indonesia, Thailand), and West Africa.
Old Tamil literature mentions the use of vetiver for medical purposes.
In-house
In the Indian Subcontinent, khus (vetiver roots) is often used to replace the straw or wood shaving pads in evaporative coolers.
In the hot summer months in India, sometimes a muslin sachet of vetiver roots is tossed into the earthen pot that keeps a household's drinking water cool. Like a bouquet garni, the bundle lends distinctive flavor and aroma to the water. Khus-scented syrups are also sold.
Soil remediation
A recent study found the plant is capable of growing in fuel-contaminated soil. In addition, the study discovered the plant is also able to clean the soil, so in the end, the soil is almost fuel-free.
Other uses
Vetiver grass is used as roof thatch (it lasts longer than other materials) and in mud brick-making for housing construction (such bricks have lower thermal conductivity). It is also made into strings and ropes, and grown as an ornamental plant (for the light purple flowers).
Agricultural aspects
Environmental requirements
{| class="wikitable"
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! Factor !! Requirements A modified seedling planter or mechanical transplanter can plant large numbers of vetiver slips in the nursery. Flowering and nonflowering varieties are used for cultivation. Sandy loam nursery beds ensure easy harvest and minimal damage to plant crowns and roots. Open space is recommended, because shading slows growth.
Overhead irrigation is recommended for the first few months after planting. More mature plants prefer flood irrigation. Weed control may be needed during establishment phase, by using atrazine after planting.