Table: Comparative Features of Epidermis and Cork Cells
Have you ever thought about what protects plants from adverse conditions or insects as these plants can't run in a dangerous situation? They have epidermis and cork cells to protect plant cells and tissues. The epidermis and cork are the outermost layer of the plant to provide protection.
They secret wax-like substances called the cuticle. It protects plants from water loss. These outermost layers also regulate gaseous exchange in plants.
What are Epidermal Cells?
The epidermis is the outer layer of the plant parts. It covers all the parts of the primary plant body. Epidermal cells are the primary component of the epidermis. In stem appendages, trichomes are also epidermal tissues. In leaves and stems, guard cells are also made of epidermal cells. The epidermis is mainly composed of parenchyma cells.
Functions of Epidermal Cells
The epidermis protects plants from water loss through transpiration because of the presence of a thick waxy layer called the cuticle.
The epidermis has root hairs that absorb water and minerals from the soil due to the large surface area.
It protects the plant from mechanical injury and other infections.
Epidermis also controls the gaseous exchange in plants.
It also controls or regulates the metabolic secretions in plants.
It also secretes various metabolic substances on the plant surface.
What are Cork Cells?
Cork is the outer protective covering of a tree. These are dead cells and do not have intercellular space. Cork cells are one of the parts of the bark, made of multiple layers of cells. When the bark of plant cells becomes old then it will be replaced by a secondary meristem.
Functions of Cork Cells
The following are the important functions of cork cells:
Like epidermal cells, these cells also prevent water loss from the plants.
It also protects the plant from various kinds of infections, especially fungal infections.
Protect plants from various injuries.
Similarity Between Epidermal Cells and Cork Cells
There are various similarities between epidermal cells and cork cells. Some of the similarities are given below:
Both epidermal cells and cork cells are the outermost covering of the plant body.
Both epidermal cells and cork cells control water loss from the internal structures of plants. These cells also ensure the correct exchange of air.
Both cork cells and epidermal cells lack chloroplast and hence they can't carry out photosynthesis
Both these types of cells release water-repellent substances.
Difference Between Epidermal Cells and Cork Cells
We have seen the similarities between epidermal cells and cork cells. But there are also many differences between these two types of cells. Some of the differences are given below:
Interesting Facts
Trees get 90% of their nutrition from the environment and only 10% from soil.
The wood is made of dead tissues that only provide mechanical support to plant tissue.
Stems of all plants are not hard, some are soft stems too.
Some plants grow from leaves. For eg., the African Violet is the plant that allows new plants to grow from leaves.
Important Questions
Q1. What is another name for cork?
Ans: The other name for cork is a phellem. It is a meristematic tissue that makes new cells through the process of mitotic divosion. Along with phelloderm and phellogen, it makes periderm.
Q2. Is cork water resistant?
Ans: Yes, cork is water resistant due to the presence of wax on the plant, which makes it water resistant. Due to its water-resistant property, it is used in many industries.
Q3. Why are epidermal cells and cork cells called protective?
Ans: Cork cells and epidermal cells are called protective tissues because they protect the plant from injury, water loss, and pathogenic attacks. They protect the plant from mechanical stresses.
Key Features
In this article, we have studied epidermal cells and cork cells.
These types of cells are present on the outer surface of the plant body.
Their main functions are to protect from mechanical stresses, and injury, prevent pathogens, and microbes, regulate gaseous exchange, and prevent water loss.
There are various similarities between epidermal cells and cork cells, such as they do not have chloroplast, and release water-repellant dance.
The differences between cork cells and epidermal cells are that cork cells form the outermost part of the secondary plant body, whereas epidermal cells form the covering of the primary plant body.
Practice Questions
Q1. How is cork formed from the epidermis?
Q2. What is cork and its function?
Q3. How is cork tissue formed?
Q4. Is cork a permanent tissue?
Q5. What is the epidermis?
FAQs on Difference Between Epidermis and Cork Cells
1. What is the main difference between epidermal cells and cork cells in plants?
The main difference lies in their origin, nature, and cell wall composition. Epidermal cells form the primary, outermost living layer (epidermis) in young plants, and their walls are coated with a waxy substance called cutin. In contrast, cork cells are dead at maturity and form a secondary protective tissue (part of the bark) in older plants. Their cell walls are heavily thickened with suberin, a waxy, waterproof substance.
2. Why are both epidermal cells and cork cells considered protective tissues?
Both are considered protective tissues because their primary function is to shield the plant from the external environment.
- The epidermis protects young plant parts from water loss (due to its waxy cuticle), mechanical injury, and invasion by pathogens.
- Cork provides similar protection to older stems and roots, but its suberin-filled, dead cells offer a more robust, waterproof, and insulating barrier against water loss, temperature changes, and physical damage.
3. Are epidermal cells living or dead? What about cork cells?
Epidermal cells are living; they contain cytoplasm, a nucleus, and other organelles necessary for metabolic activities. In stark contrast, cork cells are dead at maturity. They lose their protoplasm as they mature, leaving behind empty, suberin-impregnated cell walls that are highly effective for protection and waterproofing.
4. Where are epidermal and cork cells located in a plant?
Their location depends on the age and part of the plant. Epidermal cells form the outermost single layer (epidermis) on primary plant bodies, such as leaves, flowers, roots, and young stems. Cork cells are found in older, woody stems and roots. They are formed by the cork cambium and replace the original epidermis as the plant undergoes secondary growth and increases in girth.
5. How does the epidermis in a young stem differ from the bark in an old tree?
The epidermis is the single, living outer layer of a young stem responsible for protection and gas exchange. Bark is a much more complex, multi-layered tissue found in older trees. It includes several tissues, with the outermost protective layer being the cork (phellem). Therefore, while the epidermis is the primary 'skin', cork is a key component of the secondary, tougher 'skin' known as bark.
6. What is the difference between plant epidermal cells and animal epithelial cells?
Although both are protective outer layers, they differ fundamentally. Plant epidermal cells possess a rigid cell wall made of cellulose outside the cell membrane and often have a waxy cuticle. Animal epithelial cells lack a cell wall entirely and are only enclosed by a flexible cell membrane. This structural difference is a key distinction between plant and animal cells.
7. How are cork cells formed as a plant gets older?
As a plant stem or root ages and grows thicker (a process called secondary growth), the original epidermis stretches and breaks. To compensate, a new layer of meristematic tissue called the cork cambium (or phellogen) develops in the cortex. This cork cambium divides to produce new cork cells towards the outside, forming a new, durable protective layer that replaces the original epidermis.
8. Do epidermal cells have specialisations that cork cells lack?
Yes, absolutely. Since epidermal cells are living and metabolically active, they have several specialisations that cork cells do not, including:
- Stomata: Pores, flanked by guard cells, that regulate gas exchange and transpiration.
- Cuticle: A waxy layer secreted by the cells to prevent water loss.
- Trichomes (Hairs): Outgrowths that can help in protection, absorption, or reducing water loss.
Cork cells are uniform and dead, lacking any of these dynamic structures.
