• (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

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