Cambium is a tissue layer found in plants that provides partially undifferentiated cells for plant growth. It is located between the xylem and phloem tissues and is responsible for the secondary growth of stems and roots, which results in an increase in thickness. The cambium is a layer of actively dividing cells that originates from undifferentiated cells that have retained their embryonic capacity for continued growth and differentiation. The cambium is a single layer of cells called initial cells, but practically, it is difficult to distinguish the initials from their still-undifferentiated daughter cells, and several cell layers are collectively called the cambium or cambial zone.

The cambial cells divide to produce secondary xylem cells toward the central axis of the stem and secondary phloem cells toward the outside. There are several distinct kinds of cambium found in plant stems and roots, including cork cambium, unifacial cambium, and vascular cambium. Cork cambium is meristematic tissue that helps replace and repair the epidermis of roots in the plant. Unifacial cambium ultimately produces cells to the interior of its cylinder, while vascular cambium is a lateral meristem in the vascular tissue of plants.

In summary, cambium is a tissue layer in plants that provides partially undifferentiated cells for plant growth and is responsible for the secondary growth of stems and roots. It is located between the xylem and phloem tissues and is a layer of actively dividing cells that originates from undifferentiated cells. The cambial cells divide to produce secondary xylem cells toward the central axis of the stem and secondary phloem cells toward the outside. There are several distinct kinds of cambium found in plant stems and roots, including cork cambium, unifacial cambium, and vascular cambium.