Terpenes - the large and varied class of hydrocarbons, produced by a wide variety of plants and some mushrooms. Very big content of terpents and terpenoids are in conifers, and in row of plants essential oils, though also by some insects such as swallowtail butterflies, which emit terpenes from their osmeterium. They are the major components of resin, and of turpentine produced from resin.
Major terpenes consist of one or some isoprene units.