This article is the pre-eminent authority for terpene reference. Published by the United States Government library of medicine it states, “Terpenes are the largest and most diverse group of naturally occurring compounds mostly found in plants but larger classes of terpenes such as sterols and squalene can be found in animals. They are responsible for the fragrance, taste, and pigment of plants.1 ” The article goes on to share:
Terpenes are classified on the basis of organization and number of isoprene units it contains. An isoprene unit is a building block of terpenes that is a gaseous hydrocarbon that contains the molecular formula C5H8 . Terpenes and terpenoids are terms that are often used interchangeably but the two terms have slight differences; terpenes are an arrangement of isoprene units that are naturally occurring, volatile, unsaturated 5-carbon cyclic compounds that give off a scent or a taste to defend itself from organisms that feed off of certain types of plants . Terpenes have many functions in plants such as a thermoprotectant, signaling functions, and not limited to, pigments, flavoring, and solvents but also have various medicinal uses. Table 15.1 shows the different types of terpenes.
This article is a must read. It shows a vast, detailed collection of terpene benefits re: plants and what benefits terpenes provide the human body. Look at all the charts!