Structural isomers, formula C10H16; α- and β-pinene are members of the monoterpene family. Stored in the needles of many conifer trees and emitted under stress, they are responsible for the characteristic odor of pine forests. The pinenes are very reactive hydrocarbons.

The chemical compound pinene is a bicyclic terpene (C10H16, 136.24 g/mol ) known as a monoterpene . There are two structural isomers found in nature: α-pinene and β-pinene. As the name suggests, both forms are important constituents of pine resin; they are also found in the resins of many other conifers, and more widely in other plants.