Deep, dark, earthy and present in many oriental scents, patchouli is not a wood or a root: it is a member of the mint family with purple flowers and green leaves, called Pogostemon patchouli.
Surprisingly, from these fragile-looking leaves emanate a sweet, spicy, smoky, cedar scent so powerful that it must be handled with care: patchouli is the most potent of all plant-based essences.
The quality of the oil can vary greatly. The best product comes from the top three or four pairs of leaves, where the highest concentration of scent oil is found. On a blotter, a single drop of patchouli can last for months.