单萜类(Monoterpenes)是树脂的组成成份,在植物界分布广泛,不仅针叶树含有,阔叶树如樟科、椴科、芸香科、菊科及唇形科也都含有,但以针叶树含量较高.湿地松松脂占心材干重的25%;赤松松脂占心材干重的8%,松脂中25%是单萜.针叶树整个植物体都有树脂管分布,形成一定的树脂管系统,在受到伤害时能产生创伤树脂管. Monoterpenes, a component of resins, are widely distributed in the plant kingdom. They are not only coniferous, but also broadleaf trees such as Lauraceae, Tiliaceae, Rutaceae, Asteraceae and Labiatae, but coniferous trees are more abundant. Pinus elliottii accounted for 25% of the dry weight of the heartwood; Pinus kesiya var. Mairei accounted for 8% of the dry weight of the heartwood, and 25% of the turpentine was monoterpene. The entire plant body of the conifer was covered with a resin tube that formed a system of resin tubes that, Can produce trauma resin tube.