Meristematic tissue

• Plant Anatomy


  The study of internal structure and organization of plant, specially of its parts by means of dissection and microscopic examination
• Simplest form of plant body

  • Unicellular
  • Single cell performs all the vital functions of life: grows, performs metabolism, reproduces
• Progressive evolution in plants

  • Resulted in increasing complexity of plant structure
  • In higher plants, root, stem, leaves and flowers perform different functions
  • Cells are differentiated into different tissues
• Tissue


  A group of cells which have common origin and cooperate with each other to perform a similar or a set of similar functions
• Types of Tissue


  • Meristematic (Meristem) tissue
  • Permanent tissue
• Types of Meristematic Tissue

  • Based on origin: Prameristem, Primary meristem, Secondary meristem
  • Based on position: Apical meristem, Intercalary meristem, Lateral meristem
  • Based on function: Protoderm, Procambium, Ground meristem
  • Based on plane of division: Mass meristem, Plate meristem, Rib meristem
• Meristematic Tissue


  • Consists of immature, identical and isodiametric cells which are in a continuous state of division
  • Cells have thin cellulose cell walls, dense cytoplasm and large nucleus, small scattered vacuoles, no reserve food material, no intercellular spaces, high metabolic activity
• Types of Permanent Tissue

  • Simple permanent tissue: Parenchyma, Collenchyma, Sclerenchyma
  • Complex permanent tissue: Xylem, Phloem
  • Secretory tissue: Lactiferous, Glandular
• Differentiation is the change from meristematic to permanent tissue
• Classification of Meristematic tissue


  • Meristem based on origin
  • Meristem based on position
  • Meristem based on function
  • Meristem based on plane of division
• Promeristem/Primodial meristem


  1. Group of meristematic cells found during the earliest/youngest state of plant organelles

  2. Occupy a small space at the tip of emute plumule and radical

  3. Directly originated from the embryo

  4. Also known as embryonic meristem
• Primary meristem


  1. Arise directly from promeristem

  2. Found at the tip of root and shoot

  3. Give rise to primary permanent tissue of plant

  4. Example: intrafasicular cambium
• Secondary meristem


  1. Formed at the later stage of plant development from some of the primary permanent tissues of plant

  2. At the time of emergency, some of the simple permanent tissue of plant regain their dividing capacity and change into meristematic

  3. Example: interfasicular cambium, cork cambium
• Meristem based on position

  • Apical meristem
  • Intercalary meristem
  • Lateral meristem
• Apical meristem


  • Found at the peak of root, shoot and branches
  • Often found at the peak of leaves
  • Activity increases the length of plant parts
• Intercalary meristem


  • Intercalated between the permanent tissues
  • Found above or below the nodes
  • Also found at the base of leaves
  • Activity increases the length of internode
  • Derived from aprical meristem
• Lateral meristem


  • Lateral in position and formed at the later stage of plant development
  • Consists of single layer of rectangular cells that divide only in one plane
  • Activity increases the thickness of plant
• Meristem based on function

  • Protoderm
  • Procambium
  • Ground meristem
• Protoderm


  • Outermost protective single layer made up of meristematic cells
  • Gives rise to epidermis
• Procambium


  • Innermost layer of meristematic cells
  • Responsible for the development of primary vascular tissue i.e. Primary xylem, Primary Phloem and Cambium
• Ground meristem


  • Group of meristematic cells responsible for the development of hypodermis, cortex, endodermis, pericycle, medullary rays, pith etc.
• Meristem based on plane of division

  • Mass meristem
  • Plate meristem
  • Rib meristem
• Mass meristem


  • Consists of meristematic cells which divides in all three directions
  • Increases the volume of plant organs
  • Example: cortex, pith
• Plate meristem


  • Consists of meristematic cells which divides in two direction i.e. length and breadth
  • Increases the surface area of plant
  • Example: epidermis
• Rib meristem


  • Consists of meristematic cells which divides in one direction
  • Example: filament of spirogyra
• Functions of meristem


  • Responsible for the primary (elongation) and secondary (thickness) growth of the plant
  • Division of meristematic tissue is responsible for the emergence and the growth of new organs
  • Vascular tissues and ground tissues are formed by the meristematic tissues
  • Secondary tissues such as wood and cork are also formed due to the activity of meristematic tissues