Vetiver grass is a wild tropical plant. Its special characteristic lies in its radical structure, made up of a great mass of fibrous and resistant roots, that grow vertically  to great depths – as much as 5 m - without developing side shoots, so as not to create competition with the surrounding vegetation. The cultivated variety is sterile and this prevents it spreading into the surrounding environment, thus preventing contamination of the local flora. The depth and the sturdiness of vetiver roots has also found an industrial application against soil erosion.

If you ask someone in India what is vetiver, there is a good chance that you’d get a blank look. But if you speak of khus most people will smile. It seems that this grass has a sweet  fresh fragrance capable of dampening summer heat. That's why for centuries the Indians used vetiver mats (or khus) in their houses: a spray of aromatised water was enough to prevent the warm summer wind from entering.
There are twelve known varieties of vetiver, the most important is zizanioides of Vetiveria.

The essential oil of vetiver is extracted through vapour distillation from Andopogon squarrosus, a cultivated variety from Haiti, Java and La Reunion. In the modern perfumery vetiverile is used, a synthetic molecule obtained from the essential oil.
Aromatic description: smoky woody, earthy, grassy, spicy.