0 a layer of cells in the roots and stems of some plants that divide to produce new tissue, such as xylem and phloem -- 形成层（木本植物根部和茎部的细胞层，其通过细胞分裂形成新的木质部和韧皮部）
Inside the phloem is a layer of undifferentiated cells one cell thick called the vascular cambium layer.
The cork cambium gives rise to thickened cork cells to protect the surface of the plant and reduce water loss.
They bore in the cambium under the bark of the host plant, producing pitch masses on the trunk.
The plant has a large central medulla and a single vascular bundle containing the xylem, phloem and cambium.
The function of cork cambium is to produce the cork, a tough protective material.
The inner bark cambium and phloem tissues are living, and form a new protective layer of cells as the outer bark pulls apart.
They bore into the cambium of the trunk, branches, and twigs of their host plant.
Tree death was determined by an absence of foliage and lack of sap in the cambium.
