Meristematic tissue: characteristics, types and function




Meristematic tissue: characteristics, types and function

Characteristics of meristematic tissue

  • (Greek word; meristos- means “divisible”)
  • Meristematic tissue is a group of cells that has power of continuous division.
  • Cells are immature and young
  • Meristematic tissue is commonly called as meristems.
  • Shape of cell: each cell is oval, rounded, polygonal or rectangular
  • Size: small
  • Intercellular space: Absent
  • Cell wall: thin walled made up of cellulose
  • Nucleus: single large and prominent
  • Reserved food: cell do not store food
  • Cell division: high capacity and continuous
  • Metabolic activity: very high

 

Types of Meristematic tissue

  1.  Based on origin
  2. Based on position
  3. Based on function

 

1. Types of meristematic tissue on the basis of origin:

i. Promeristem (primodial meristem)

ii. Primary meristem

iii. Secondary meristem

Promeristem:

  • Origin: embryonic origin
  • It is earliest and youngest meristematic tissue
  • It is present in growing root and shoot tip.
  • It give rises to primary meristem,

Primary meristem:

  • Origin: from Promeristem
  • Cell are always active and dividing
  • Present below promeristem in the shoot and root tip, and also in intercalary position
  • It give rises to secondary meristem, and primary permanent tissue.

Secondary meristem:

  • Origin: from primary meristem
  • It is developed later on life
  • It give rises to secondary permanent tissue

 

2. Types of Meristematic tissue on the basis of position:

i. Apical meristem

ii. Intercalary meristem

iii. Lateral meristem

Apical Meristem:

  • Position: present at apical parts of plant such as root tip and shoot tip
  • It helps in increase in height of plants.
  • Apical meristem has two distinct zone:
  • Promeristem zone: contains group of dividing cell (apical initials)
  • Meristematic zone: contains protoderms (epiderm), procambium (primary vascular tissue) and ground meristem (cortex and pith).

Intercalary Meristem:

  • Position: present in intercalary position in the leaves and internode
  • It is a part of apical meristem
  • It also adds to height of plants
  • Commonly present in monocots, grass and pines

Lateral Meristem:

  • Position: present on lateral side of stem and root
  • It helps in increases the diameter or thickness of plants.
  • Example: vascular cambium (primary meristem) and cork cambium (secondary meristem)

 

3. Types of meristematic tissue on the basis of function:

i. Protoderm

ii. Procambium

iii. Ground meristem

Protoderm:

  • Function: protection from mechanical injury
  • It gives rise to epidermis layer.
  • It is the outermost meristematic tissue

Procambium:

  • Function: transport of water and nutrition
  • It gives rise to vascular tissue (xylem and phloem)
  • It is the innermost meristematic tissue

Ground meristem:

  • Function: various functions
  • It gives rise to cortex, endodermis, pericycle and pith in dicot and hypodermis, ground tissue in monocot.

Meristematic tissue: characteristics, types and function