These essences are combinations of various alcohols, hydrocarbons, phenols, aldehydes, esters, and ketones that occur naturally in the plant.
Essential oils come from flowers, blossoms, leaves, fruit, rind, peel, seeds, bark, wood, and resin.
The part of the plant varies according to the purpose and use of the essential oil. The oil is connected to so many of the biological properties of the plant that it's considered essential to the plant and so is referred to as essential oil. Essential oils are like human hormones. They exist in very small quantities within the plant. Due to the highly concentrated nature of essential oils, most applications require drops, rather than ounces.