There are two zones of cambium: the VASCULAR CAMBIUM, which produces secondary xylem and phloem, and the PHELLEM (cork cambium), which produces secondary cortex and cork or bark.

• 有两种类型的形成层：一种是维管形成层，产生次生木质部和次生韧皮部。另一种是木栓形成层，产生次生皮层，软木或树皮。