An ethnobotanical profile of Vetiver grass

Vetiver (Chrysopogon zizanioides) is a perennial grass endemic to India, that was transported around the world more than a century ago. Commonly known under the names Vetiver, Vetiver grass or khus-khus, this incredibly resilient plant is used to stabilise the soil, to clean polluted environments, in handicraft, medicine and food, perfumery and aromatherapy.

The ‘golden beard’ that grows ‘by the riverside‘

Chrysopogon originates from Pogon, Greek for beard, and Chrysos, Greek for gold. Golden beard refers to the golden hairs at the base of the groups of spikelets. The epithet zizanioides means “by the riverside” referring to the original native habitat of this plant (Council, 1AD). There are at least 61 known common names, frequently occurring are; Cus-Cus, Cuscus Grass, Indian Couch Grass, Khus-Khus Grass, Kuskus, Vetiver, Vetiver Grass, Vetiveria (MPNS, 2020; Lim, 2016). The name vetiver originates from India, in Tamil ‘ver’ means root and vettiveru means ‘root that is dug up’ (IPNI, 2020). In the evolutionary tree of life, the plant is positioned in the family of Poaceae or grasses. Its accepted name is now Chrysopogon zizanioides, however the plant is known under at least 22 scientific synonyms and Vetiveria zizanioides is more often used in literature.

The botanical description

Vetiver grass is a monocotyledonous flowering perennial grass, forming large, dense clumps (Lim, 2016). This hemicryptophyte is considered a tussock grass or bunch grass. It has a finely structured, fibrous root system which grows between 2 and 4m deep. Vetiver grass belongs to the C4 photosynthetic pathway (NADP-ME variant) which explains its fast growth, allowing a harvest several times per year (Bertea et al., 2001; Wongwatanapaiboon et al., 2012). Vetiver grass has a finely structured, fibrous root system, the roots are the odorous part of the plant and they are of a spongy and strong material (Lavania, 2003). The culms are robust, and stand very tall, up to 1–2.5 m. They are about 5 mm in diameter, the nodes are concealed within the leaf sheaths, which are laterally compressed and imbricate in fanlike clusters  (Lim, 2016). The leaves are pale green and stiff, with a length of 30 to 90 cm and 0.5cm to 1cm in width.

The plant bears small brown-purple flowers in long indeterminate spikes. The panicle is up to 30 cm long or more, with whorls 6–10 each with up to 20 racemes (POWO, 2020). The androecium consists of 3 stamens with orange anthers, the gynoecium consists of 2 plumose, purple stigmas. North Indian vetiver is wild and fertile, whereas ‘typical’ cultivated vetiver is sterile and non-seeding (Belhassen, 2015)

Geography & Conservation

Vetiver is native to tropical Asia, in India, Pakistan, Nepal, Myanmar, Sri Lanka and South East Asia and is cultivated in tropical Africa, China, United States and Costa Rica (Lim, 2016). It has been introduced in over 22 countries, in Southern Asia, central Africa, and southern and central America (Lim, 2016; POWO 2020). Vetiver is grown commercially for oil mostly in Java, the Seychelles, Réunion, Brazil, Haiti and Japan (Battaglia, 2018). Vetiver grass is also grown for the purpose of erosion control and soil restoration in the United Kingdom (www.vetivergrassuk.org, n.d.). As a native plant, it grows in lower regions, ascending up to an altitude of 1200m.

Vetiver grass is tolerant of extreme variations in soil and climate. The plant is considered a xerophyte, tolerating long periods of drought, it can withstand wide ranges of soil pH (pH from 3.3 to 12.5), can survive being submerged under water for an extended period, and tolerates extreme temperatures from −14 °C to +55 °C (Lim, 2016; Pareek and Kumar, 2013). Because the cultivated variation of Chrysopogon zizainoides is a sterile tussock grass it has not become invasive. The species has not yet been assessed for the IUCN Red List, there no reason to believe it is threatened.

The ethnobotany of vetiver grass

Ecological uses
The original use of vetiver in India was to prevent soil erosion, preventing the loss of soil on mountainous slopes from excessive erosion during the wet season (Battaglia, 2018). It is still used for this purpose in more than 100 countries (Belhassen, 2013). Vetiver significantly enhances the degradation of heavy metals such as aluminium, cadmium, chromium, copper, lead, nickel, plutonium and polycyclic aromatic hydrocarbons in the soil (Lim, 2016; Singh, Fulzele and Kaushik, 2016). It has shown to remove 90% of antibiotics was from wastewater in 90 days (Panja et al., 2020). This makes Vetiver suitable for wastewater treatment and rehabilitation of old mines. The Vetiver system, a global technology of soil conservation and water quality management, is based on these qualities (www.vetiver.org, n.d.). Vetiver can also protect fields against pests and weeds (Olotuah, 2016, Aarthi, 2010), is suitable for biofuel production (Wongwatanapaiboon et al., 2012) and for animal feed.

Handicraft

In India, since ancient times, the fibrous roots have been used for handicrafts such as screens, mats, hand fans, ropes, hats and baskets (Pareek and Kumar, 2013; PFAF, 2020). Vetiver screens or blinds are traditionally doused with water throughout the day, adding coolness and a therapeutic aroma to the warm breeze.

Food and medicine

Khus (Vetiver) syrup is used as a flavouring agent for milkshakes and yogurt drinks like lassi. Vetiver tonic is traditionally used in Ayurvedic medicine to alleviate thirst, heatstroke, fever and headaches. The oil is applied as part of a liniment to relieve inflammation of the joints and skin, and it has been used for rheumatoid arthritis. It is also used to dissolving kidney stones, for boils, burns, epilepsy, fever, scorpion sting, snakebite, and sores in the mouth (Battaglia, 2018; Pareek and Kumar, 2013).

Perfumery and aromatherapy

Vetiver essential oil is a valued ingredient in perfumery, even before the world became familiar with rose scents. The oil is amber brown and one of the most viscous essential oils. Its odour is described as deep, sweet, woody, smoky, earthy, amber and balsam. It is used extensively in the soap and cosmetic industries, and as antimicrobial and anti-fungal agent (Pareek and Kumar, 2013). Traditionally, it has been used in aromatherapy for relieving stress, anxiety, nervous tension and insomnia. Vetiver is said to be beneficial for grounding and centering energies, bringing one into close contact with the earth (Battaglia, 2018).

Phytochemistry

Vetiver essential oil is one of the most complex essential oils known. Until now, 300 molecules have been reported. The unique earthy odour of vetiver is due to two sesquiterpene ketones α-Vetivone (C15H22O) and β-vetivone (C15H22O), although much contradictory information appears in the literature on this subject (Battaglia, 2018; Belhassen, 2016). In India, oils produced from Vetiver collected in the wild and from cultivated vetiver are differentiated by calling the former Khus oil and the latter vetiver oil. These oils have different chemotypes.