Differences Between Collenchyma and Sclerenchyma

October 10, 2022

INTRODUCTION

Plant tissues are categorized into three types. They are meristematic tissues, permanent tissues and secretary tissues. These tissues are further grouped into various types. Among them, permanent tissues are divided as simple permanent tissues and complex permanent tissues.

Simple permanent tissues are formed of group of cells which are all alike in origin, form and function. They are made up of one type of cells forming a homogeneous or uniform mass.

Whereas, complex permanent tissues are the group of different types of cells that are adapted to perform a common function. They are generally found in all vascular plants.

Simple permanent tissues are of three main types. They are parenchyma, collenchyma and sclerenchyma. Parenchyma is the most common permanent tissues in plants among all of them.

FEATURES OF COLLENCHYMA AND SCLERENCHYMA

Collenchyma tissues contain cells which are somewhat elongated, living and often contain some chloroplasts. The cells of this tissue possess localized thickening on the cell wall, particularly at the corner or intercellular spaces. This thickening is due to the deposition of cellulose and pectin. Their walls are provided with simple pits. This tissue generally occurs in the stem of herbaceous dicotyledons in the form of two layers below the epidermis and forms a layer, called the hypodermis. Its presence is not noticed in roots and monocotyledons except in some special cases. The presence of cellulose and pectin substances in the thickened wall endows tissue with capacity to expand and give a tensile strength to the organs.

FUNCTIONS OF COLLENCHYMA

They give mechanical strength to the organs and due to its peripheral positions in the stem, resist the bending and pulling action of the wind.
In some leaves the hypodermal tissue is located at the margin of lamina and saves it from tearing effect of the wind.
Also manufactures sugar and starch by the process photosynthesis as it contains chloroplast.
In some plants, they become thin-walled and regain the power to divide.

Sclerenchyma tissues are the tissues that form the main strengthening tissue of the plant. They consist of long, narrow, thick-walled and lignified dead cells. They are usually pointed at both the ends and are fiber like in appearance and hence called sclerenchymatous fibers or simple fibers. They have simple, often oblique pits in their walls. The middle lamella is conspicuous in sclerenchyma. They are found abundantly in plants, and occur in patches or in definite layers.

FUNCTIONS OF SCLERENCHYMA

Important supporting tissues in plants.
Provides hardness to the seeds of various fruits and shell of walnuts.
May play role in the transport of water in the plant.
Starch granules are stored in the young, living fibers.

Differences between collenchyma and sclerenchyma

Collenchyma	Sclerenchyma
Collenchyma cells are living.	Cells are generally dead.
Cells are filled with protoplasm.	Cells are empty.
Wall thickening is not uniform.	Wall thickening is uniform.
Lumen or cavity is wide.	Lumen or cavity is usually narrow.
Wall thickening consists of cellulose and pectin.	Wall thickening can be of cellulose, lignin or both.
Pits are simple and straight.	Pits are usually simple and oblique.
Provides mechanical strength as well as elasticity.	Simply a mechanical tissue.
Found in petiole, leaves and young stems.	Found in the mature part of the plants.
No or little intercellular space is present between the cells.	No intercellular space is present between the cells.
Shapes are variable.	Shape generally elongated.
Nucleus may be seen.	Absent at maturity.
Vacuoles present. Image source: aakash.ac	Vacuoles are absent. Image source: onlinebiologynotes