Plant Tissues

Plant tissues are divided into two types:

1. Meristematic tissue — They divide rapidly and continuously as a result of which the plant gains height. Based on their location in the plant body, they are of two types:
   1. Apical meristematic tissue — It is present at the root and shoot tips. It increases the length of the plant.
   2. Lateral meristematic tissue — This meristematic tissue is present on the lateral sides of the root and stem. This tissue is called the lateral meristematic tissue or cambium. It is responsible for the increase in the thickness of the roots and stem.
2. Permanent tissue — These tissues perform specific functions. They are classified into two types:
   1. Simple permanent tissue — This tissue provides support and protection to plants and is further classified into two types:
      1. Protective tissue — Epidermis and Cork are two protective tissues in plants.
      2. Supporting tissue — Supporting tissue comprises of Parenchyma, Collenchyma and Sclerenchyma.
   2. Complex permanent tissue — The main function of these tissues is to transport water and food materials. Therefore, these tissues are also called conducting tissues. It comprises of Xylem and Phloem.

The diagrams are shown below:

Parenchyma

Collenchyma

Sclerenchyma

The Conducting tissue has two elements:

1. Xylem — Xylem is the water-conducting tissue of plants. It is composed of vessels, tracheids, fibres and xylem parenchyma.
   1. A xylem vessel is not one cell but a series of cells joined from end to end to form a long tube.
   2. Tracheids are usually long and narrow cells that taper at the ends. Both tracheids and vessels do not have living protoplasm at maturity. They are involved in the transportation of water from the roots to the upper parts of the plant.
   3. Fibres provide strength to the tissue. They also lack living protoplasm at maturity.
   4. Xylem parenchyma is the only living component of xylem. It helps in the conduction of water and also stores food.

The below diagram shows the lateral section of Xylem tissue:

2. Phloem — Phloem is the food-conducting tissue of plants. It is composed of different types of cells namely, sieve cells, phloem fibres and phloem parenchyma. It consists of living cells with protoplasm in them.
   1. Sieve cells are elongated cells with minute pores. They do not have a nucleus at maturity. They help in the transportation of food prepared in the leaves to other parts of the plant.
   2. Phloem fibres provide mechanical strength to the plant.
   3. Phloem parenchyma cells are involved in the storage of reserve substances. Certain specialized parenchyma cells, closely associated with sieve cells are known as companion cells.

The below diagram shows the lateral section of Phloem tissue:

The various types of cells present in xylem are

1. Xylem vessels — A xylem vessel is not one cell but a series of cells joined from end to end to form a long tube. Its function is transportation of water.
2. Tracheids — Tracheids are usually long and narrow cells that taper at the ends. Both tracheids and vessels do not have living protoplasm at maturity. They are involved in the transportation of water from the roots to the upper parts of the plant.
3. Fibres — Fibres provide strength to the tissue. They also lack living protoplasm at maturity.
4. Xylem parenchyma — Xylem parenchyma is the only living component of xylem. It helps in the conduction of water and also stores food.

The group of cells that are similar in structure and functions are called Tissue.

The tissue that consists of actively dividing cells is called Meristematic Tissue. They are present at root and shoot tips and lateral sides of root and stem.

Sclerenchyma tissue provides mechanical strength to the stem.

The vascular system of the plant consists of Xylem tissue and phloem tissue.

The tissue that helps in conduction of

(a) water — Xylem tissue

(b) food — Phloem tissue

True

False

Corrected statement — A meristematic tissue is a group of cells that are capable of active cell division.

True

False

Corrected statement — Xylem parenchyma is the only living component of xylem.

True

Meristematic Tissue — The tissue that consists of actively dividing cells present at root and shoot tips and lateral sides of root and stem is called Meristematic Tissue.

Permanent Tissue — The tissue that consists of cells that get differentiated to perform specific function and do not grow or produce new cells are called Permanent Tissue.

Protective Tissue — The permanent tissue which forms the outer protective covering of the plant and protects it from external influence is called protective tissue. For example - Epidermis, cork.

Supporting Tissue — The tissue that comprises the bulk of the plant body and provides support to it is called supporting tissue.

Complex permanent tissue — Complex permanent tissue are the tissues that are made up of two or more types of cells that are specialized to perform a common function. For example - Xylem and Phloem.

Conducting tissue — The complex permanent tissues that transport food and water to different parts of plants are called conducting tissue. Xylem and Phloem are two conducting tissues in plants.

A group of actively dividing cells forms the meristematic tissue.

Apical meristematic tissue increases the length of the plants.

Lateral meristematic tissue increases the thickness of roots and stem.

Simple permanent tissue provides support and protection.

Complex permanent tissue transports nutrient and water.

The outer walls of the epidermis are usually thick and covered with cutin.

In leaves, the epidermis has special cells called guard cells.

The fibres of jute and husk of coconut is made up of sclerenchyma tissue.

A xylem vessel is not one cell but a series of cells.

Phloem is located on the outer side of the vascular bundle.

vascular bundle

Reason — Complex permanent tissues Xylem and Phloem together are called the vascular bundle whereas parenchyma, collenchyma and sclerenchyma are simple permanent tissue.

xylem parenchyma

Reason — Xylem parenchyma is a part of xylem, rest all are part of phloem tissue

collenchyma

Reason — Collenchyma is a simple permanent tissue whereas companion cells and sieve tubes are part of Phloem and vessels are part of Xylem.

The completed table is given below:

Structure	Name	Location	Function
	Apical Meristematic Tissue	Root and shoot tip	Increases the length of the plant
	Parenchyma	All parts of the plant	Helps in photosynthesis and store food
	Collenchyma	Below epidermis in young stem and petioles	Structural support to growing stems and leaves
	Sclerenchyma	Stems and veins of leaves	Provides mechanical strength to the stem
	Xylem tissue	Stem and roots	Transportation of water and minerals
	Phloem tissue	Stem and roots	Transportation of food.

actively dividing cells

Reason — Meristematic tissues consist of actively dividing cells and are present at the root and shoot tips and on the lateral sides of the root and stem.

Vacuoles are mostly present

Reason — Vacuoles are mostly absent in meristematic tissues.

apical meristematic tissue

Reason — Apical meristematic tissue is present at the root and shoot tips. It increases the length of the plant.

cork

Reason — Cork is a protective tissue located at the periphery of the roots and stem.

sclerechyma

Reason — Cells of sclerenchyma are dead and have cell walls thickened with lignin.

vessels, tracheids, fibres and xylem parenchyma.

Reason — Xylem is the water-conducting tissue of plants. It is composed of vessels, tracheids, fibres and xylem parenchyma.

Xylem

Reason — All the parts of xylem are dead except xylem parenchyma.

sieve cells, phloem fibres and phloem parenchyma

Reason — Phloem consists of sieve cells, phloem fibres and phloem parenchyma.

sieve cells

Reason — Sieve cells are elongated cells with minute pores.

xylem and phloem

Reason — Phloem and xylem together are called the vascular bundle.

True

False

Corrected statement — Protective tissue consists of epidermis.

True

False

Corrected statement — Xylem is made up of dead cells.

True