Citrus peel, hops, pine needle, rosemary, lavender, mint, and eucalyptus; as well as a host of other flowers and herbs; are the leading sources (by quantity) of terpenes. These compounds are produced by plants as a form of defense against predators, and also for communication with other plants. This accounts for the abundance of foods and fragrances containing terpenes and terpene-rich essential oils.
