One of a pair of phellandrene cyclic monoterpene double-bond isomers in which both double bonds are endocyclic (cf. alpha-phellandrene, where one of them is exocyclic). ChEBI: Alpha-phellandrene is one of a pair of phellandrene cyclic monoterpene double-bond isomers in which both double bonds are endocyclic (cf. alpha-phellandrene, where one of them is exocyclic). It has a role as a volatile oil component, a plant metabolite and an antimicrobial agent. It is a phellandrene and a cyclohexadiene.