If the same phellogen functions from year to year, as in beech and oak, then the bark is smooth and consists only of tissue external to the phloem, mainly cork. 如在榉木或橡木中，相同的木栓形成层年复一年的活动，那么树皮是光滑的，并且仅形成韧皮部的外方组织，主要是木栓（软木）。
Bark The outermost tissue of the stem and roots in woody plants, on the outside of the phellogen (cork cambium). bark树皮：木本植物中的茎或根中木栓形成层外方的全部组织，称为树皮。
Phellogen layer structure was seen inside the pedicel wart of all cultivars observed but Red globe.Fungi mycelium was also observed in the pedicel wart of all cultivars except Beichun. 发现抗性较强的北醇，小果柄上的疣小、形成较早，发育速度较慢，破裂后内部结构层次清晰，基部木栓形成层明显，抗性差的红地球则相反。
5.If the same phellogen functions from year to year, as in beech and oak, then the bark is smooth and consists only of tissue external to the phloem, mainly cork. 如在榉木或橡木中，相同的木栓形成层年复一年的活动，那么树皮是光滑的，并且仅形成韧皮部的外方组织，主要是木栓（软木）。
