The periderm is a protective tissue that replaces the epidermis in woody plants. As secondary growth continues, the outer layers of the periderm, including the cork (phellem), accumulate and eventually form the bark. Bark is a collective term for all tissues outside the vascular cambium, including the periderm and secondary phloem.

Secondary phloem is the vascular tissue generated by the vascular cambium during the process of secondary growth in woody plants. It is produced toward the periphery of the stem or root, complementing the secondary xylem produced toward the interior.

Cork cambium, or phellogen, is a lateral meristem responsible for secondary growth in the periderm. It typically develops in older stems and roots that have undergone significant secondary thickening. Young stems are usually covered by an epidermis and have not yet initiated the formation of the cork cambium.

Secondary xylem is produced by the vascular cambium during secondary growth in woody plants. It is responsible for the increase in the girth of stems and roots and constitutes the bulk of the wood in trees and shrubs.

The phellogen, also known as the cork cambium, is a lateral meristem responsible for secondary growth in the periderm. It produces cork (phellem) towards the outside and phelloderm towards the inside. This activity results in the formation of the outer bark, which serves as a protective layer for the stem, replacing the epidermis as the plant increases in girth.

The cambium is a layer of meristematic tissue found between the xylem and phloem in vascular plants. It is responsible for secondary growth, producing secondary xylem towards the inside and secondary phloem towards the outside. This activity increases the girth of the stem or root over time.

Cork production, or phellogenesis, is a key component of secondary growth in woody plants. It occurs when the cork cambium (phellogen) produces cork cells (phellem) toward the outside of the stem or root. This process replaces the epidermis with a protective, water-impermeable layer, which is essential for the survival and structural integrity of perennial plants as they increase in girth.

Secondary growth, which results in an increase in the girth or thickness of the plant stem and root, is facilitated by lateral meristems. The vascular cambium is the primary lateral meristem that produces secondary xylem (wood) and secondary phloem, allowing the plant to increase in diameter over time.

The vascular cambium is a lateral meristem responsible for secondary growth in plants. By producing secondary xylem (wood) towards the inside and secondary phloem towards the outside, it increases the girth or diameter of the stem and root, allowing for structural support and increased transport capacity in woody plants.

Secondary xylem is organized into two distinct systems: the axial (or vertical) system and the radial (or horizontal) system. The axial system consists of tracheids, vessels, and fibers that conduct water vertically, while the radial system consists of xylem rays that facilitate the lateral transport of water and nutrients across the stem.