SECONDARY GROWTH (link)

• Tissues generated from the growth of an apical meristem.

  Primary tissues
• A lateral meristem constituting a sheet of cells. Growth of these cells increases the girdth of the plant organ involved.

  Cambium
• Tissues generated from the growth of a cambium.

  Secondary tissues
•  A cambium that gives rise to secondary xylem to the inside, and to secondary phloem to the outside.

  Vascular Cambium
• A structure that consists of a cork cambium (phellogen), with cork tissue (phellem) to the outside, and in some cases a layer of cells derived from and to the inside of the cork cambium called phelloderm. Functions to limit dehydration and block pathogens after the epidermis is disrupted by the onset of secondary growth


  Periderm
• Tissue dead at maturity generated from a cork cambium. The cell walls of the tissue are impregnated with suberin. This water-proofs the tissue.

  Cork (Phellem)
• A cambial layer that functions to produce cork, and in some cases, phelloderm

  Cork Cambium
• In roots is derived initially from pericyle.

  Cork Cambium
• In stems from the cortex. Unlike the vascuar cambium these cambial layers do not persist for the duration of the life of the plant organ.

  Cork Cambium
• In some periderms a layer of living secondary tissue is generated by the cork cambium to the inside.

  Phelloderm