Among the non-saponifiable lipids found in plants are mainly hydrocarbon known as terpenes. The simplest terpenes are called monoterpenes and conform the formula C₁₀H₁₆ (equivalent to two isoprene units), sesquiterpenes with the formula C₁₅H₂₄, diterpenes with C₂H₃₂, and triterpenes C₃₀H₄₈.