Cymbopogon citratus is often sold in stem form. While it can be grown in warmer temperate regions, such as the UK, it is not hard to frost.

Lemongrass is a tender perennial grass, which is native to India, but also cultivated in other tropical areas, particularly Brazil, Sri Lanka and parts of central Africa. After harvesting, grass is finely chopped to facilitate the extraction of the essential oil by steam distillation.
Cymbopogon flexuosus is a fast-growing and lemon-scented grass, which may reach a height of 1 m. It has unusual, dark-green foliage and also produces seeds. 
The main chemical component of lemongrass oil is citral.