Vascular cambium The ring of CAMBIUM formed by the activity of the interfascicular cambium and the intrafascicular cambium that gives rise to secondary xylem and secondary phloem.

• 维管形成层：由于维管束内形成层和束间形成层的活动产生的环状形成层结构，它的分裂活动可以形成次生木质部和次生韧皮部。