The periderm consists of three layers:(1) The phellem (木栓層), the layer of cork cells formed by the phellogento the outside.(2) The phellogen (木栓形成層)(cork cambium),a uniseriate (單列) layer of meristematic initials, and(3) The phelloderm (綠皮層),a layer consisting of one or more rows of thin-walled cells formed by the cork cambium to the inside