What is a Tissue?

A tissue is a group of similar or related cells that:

Have a common origin
Are structurally and functionally similar

These cells work together to perform specific roles in the plant's body—whether it's supporting the stem, storing food, or conducting water.

Classification of Tissues

Tissues are broadly divided into:

Plant Tissues
Animal Tissues

In this blog, we focus solely on Plant Tissues, which are further classified as:

Meristematic Tissues
Permanent Tissues

1 Meristematic Tissues

These are the growth zones of plants. Meristematic tissues consist of actively dividing, undifferentiated cells that contribute to:

Primary growth (length)
Secondary growth (thickness)
Regeneration of parts

Key Characteristics:

Thin-walled, compact cells
Dense cytoplasm
Prominent nuclei
No vacuoles
No intercellular spaces

NEET Tip: Meristematic tissues lack vacuoles and remain in a constant state of mitosis.

Types of Meristematic Tissues

1. Apical Meristem

Location: Tips of roots and shoots
Function: Primary growth – increases plant length
Example: Root/shoot apex in mustard

2. Lateral Meristem

Location: Along sides of roots and stems
Function: Secondary growth – increase in thickness or girth
Example: Vascular cambium, cork cambium in dicot stems (e.g., sunflower, banyan)

3. Intercalary Meristem

Location: Base of leaves or internodes
Function: Regrowth and elongation of internodes
Example: Base of grass leaves (regrow after mowing)

2 Permanent Tissues

As meristematic cells mature, they differentiate and lose their ability to divide, forming permanent tissues. These tissues perform specialized roles in support, storage, transport, and protection.

Permanent tissues are of two types:

Simple Permanent Tissues
Complex Permanent Tissues

Simple Permanent Tissues

Formed by one type of cell, they are involved in support, storage, and basic functions.

1. Parenchyma

Thin-walled living cells
Store food and water
Can photosynthesize when containing chloroplasts (called chlorenchyma)
In aquatic plants, they may form aerenchyma (for buoyancy)
Example: Pith in sunflower stem, fleshy fruits like pear

2. Collenchyma

Living cells with unevenly thickened corners
Provides mechanical support and flexibility
Found in growing regions (leaves, young stems)
Example: Petioles of pumpkin, midrib of mustard

3. Sclerenchyma

Made of dead, lignified cells
Provides maximum strength
Two types:
- Sclereids: Short, irregular (e.g., grit in pears)
- Fibres: Long, tapered (e.g., jute)
NEET Tip:
- Sclereids = Hard Protection
- Fibres = Strength and Flexibility

Complex Permanent Tissues

Composed of different types of cells working together to perform a common transport function.

Xylem – The Water Carrier

Function: Conducts water and minerals from roots to leaves & provides support.

Components:

Tracheids – Long, tapering, dead; present in all vascular plants
Vessels – Wide, tubular; present mostly in angiosperms
Xylem Fibres – Dead, supportive
Xylem Parenchyma – Only living xylem cells (for storage)

NEET Tip:

Tip: Tracheids + Vessels = Main conducting elements

Tip: Derived from: Procambium (Primary xylem) & Vascular cambium (Secondary xylem)

Phloem – The Food Distributor

Function: Transports organic nutrients, especially sucrose, from source (leaves) to sink (roots, fruits, storage organs).

Components:

Sieve Tube Elements – Main conducting cells; lack nucleus
Companion Cells – Control & support sieve tubes
Phloem Parenchyma – Stores food
Phloem Fibres – Only dead phloem component

NEET Tip: Sieve tubes are functional due to companion cells

Tip: Sieve tubes are functional due to companion cells

Tip: Phloem Parenchyma is absent in monocots

Tip: Bidirectional transport (unlike unidirectional xylem)

NEET Summary Table: Xylem vs Phloem

NEET Practice Questions

Q1. Which of the following xylem components is living?

Tracheids
Vessels
Xylem Fibres
Xylem Parenchyma

Q2. Which phloem cell lacks a nucleus but functions with the help of a companion cell?

Phloem Fibre?
Phloem Parenchyma?
Sieve Tube Element
Xylem Parenchyma

Q3. Which phloem component is absent in monocots?

Sieve tubes?
Companion cells?
Phloem fibres?
Phloem parenchyma

Q4. What gives gritty texture to fruits like guava?

Parenchyma?
Collenchyma?
Sclereids
Xylem vessels

Q5. What tissue allows regrowth in grasses after mowing?

Apical meristem?
Intercalary meristem
Lateral meristem?
Parenchyma

Plant Tissues Explained: Meristematic & Permanent