The various species of Lavandula produce complex mixtures of hundreds of volatile organic compounds that are stored in specialized plant structures. The characteristic scents that we attribute to various lavender varieties are almost entirely related to these mixtures of natural aroma molecules. The plants produce the oils for several purposes, including the attraction of pollinators and the repulsion of herbavores. While it is possible to extract the oils from plant material (mainly the flower spikes) in several ways, most essential oil is a product of steam distillation. During the distillation process, the volatile components of the essential oil are forced into the vapor phase, and subsequently re-condensed into oil and water phases which can be separated fairly easily. (The water phase from lavender distillation is often aged, bottled and sold as “lavender hydrosol” or “flower water.”)
