Tissue system 



Collection of many different tissues to perform many collective functions are called tissue system.

There are three types of tissue system


A. Epidermal tissue system

B. Ground / fundamental tissue system

C. Vascular / Stele / conducting tissue system




A. Epidermal tissue system - 


 This tissue system includes epidermis (outer layer of plant body) and stomata , trichomes and hairs.


1. Epidermis -

It is outer most layer which is made up of elongated , compact and arranged cells.

Epidermal cells are parenchymatous which have less cytoplasm and large vacoule.

A thick, waxy layer (cuticle) is present arround epidermis to present to present loss of water.


2. Stomata - 

It is present on epidermis of leaf and regulate transpiration and gaseous exchange.

Stomatal pores are enclosed by two dumble cells called guard cell.

Guard cell possess chloroplast and regulate the oopening and closing of stomata.

Outer walls of guard cells is thin and inner wall (towards pore) is thick.

Some epidermal cells become specific in their shape and size called subsdiary cells.

Guard cells and subsdiary cells toghter called stomatal apparatus.


3. Trichomes - 

On stem, epidermal hairs are present called trichome.

Trichomes are multicellular, branched, unbranched, soft/stiff and secretory in nature.

Trichomes help to prevent water loss by transpiration.


4. Root Hairs - 


It is formed due to elongation of epidermal cells in roots.

It's thin wall is made up of cellulose and pectin. (pecto-cellulose)

It helps in absorption of water and minerals from the soil.


B. Ground / fundamental tissue system-

It is largest tissue system except epidermis and vascular tissue system.

It includes hypodermis, general cortex, endodermis, pericycle, pitch rays etc.

In leaves, the ground tissue consist of thin - walled chloroplast containing cells called mesophyll cells.

It consist of simple tissue as parenchyma, collenchyma and sclerenchyma.

It manufacture and store food material and also provide the mechanical support.


C. Vascular / Stele / conducting tissue system -

It consist of xylem and phloem.

 It originates from pro- cambium.

 It vascular tissue have two types of vascular bundels -
1. Open Vascular Bundle 

 2. Closed Vascular Bundle

1. Open Vascular Bundle  -


In dicot stem, cambium is present between xylem and phloem.

These xylem and phloem can form secondary xylem and phloem due to presence of cambium.


 2. Closed Vascular Bundle -  

In monoroots, Cambium is present so, they cannot form secondary xylem and phloem.



Arrangement Of Xylem And Phloem -

1.  Two Types Of Arrangements -


1. Radical

1. Conjoint


1. Radical -


In roots, xylem and phloem arranged in alternate manner on different  radius , this arrangement is called radical arrangement.


2. Conjoint -

 In stem and leaves, xylem and phloem situated at same radius of vascular bundle.

Conjoint vascular bundles have the phloem located only on the outer side of xylem.