Main Difference – Epidermal vs Cork Cells
Epidermal cells and cork cells are two types of cells found in the outermost layer of plants. They occur in different parts of the pant body at different stages. The main difference between epidermal cells and cork cells is that epidermal cells cover the entire plant body during primary growth whereas cork cells cover the stem and root of the plant after the secondary growth of the plant. Epidermal cells are found in leaves and other immature parts of the plant. They occur as a single layer of cells. Cork cells originate from the cork cambium.
Key Areas Covered
1. What are Epidermal Cells
– Definition, Formation, Function
2. What are Cork Cells
– Definition, Formation, Function
3. What are the Similarities Between Epidermal and Cork Cells
– Outline of Common Features
4. What is the Difference Between Epidermal and Cork Cells
– Comparison of Key Differences
Key Terms: Bark, Cork, Cork Cambium, Cork Cells, Cutin, Epidermal Cells, Primary Growth, Secondary Growth, Suberin
What are Epidermal Cells
Epidermal cells refer to the outermost layer of cells on the primary plant body. It covers the leaves, flower, fruit, seed, stem as well as the root of the plant during the primary growth of the plant. It is a primary component of the epidermis of a plant. Plant epidermis contains guard cells and trichomes as well. Upper epidermis and lower epidermis of a leaf of a plant are shown in figure 1.
Figure 1: Upper and Lower Epidermis of a Leaf
A single layer of epithelial cells occurs in plants. Epidermal cells lack chloroplasts. They secrete a waxy substance called cutin on top of the cells. The cuticle layer prevents the water loss from the internal structures of the plant. It also protects the plant body from mechanical injuries as well as infections. During the secondary growth of a plant, epidermal cells in the mature stem and root are replaced by the bark.
What are Cork Cells
Cork cells refer to the cells in the outermost layer of the secondary stem and root. Cork cells originate from the cells divided from the cork cambium to the outside of the plant body. Several layers of cork cells form the cork, which is the outermost layer of the bark. Each cell layer is arranged in radial rows. Lenticels, which are pore-like structures, separate the cells in the cork. The overproduction of the cells by the cork cambium may form ridges or deep cracks in the bark. Cork cells in the outermost layer of a woody dicot stem are shown in figure 2.
Figure 2: Cork Cells in a Woody Dicot Stem
Mature cork cells are non-living cells and their cell walls are composed of suberin. Suberin is a waxy substance, which is impermeable to water and gases. However, lenticels allow the gas exchange through the cork. In some woody plants, cork is filled with air. Some cork cells may contain lignin, fatty acids or tannins. The main function of the cork is to provide protection and extra insulation to the plant.
Similarities Between Epidermal and Cork Cells
- Epidermal cells and cork cells are two types of cells, which occur in the outermost layer of a plant.
- Both epidermal cells and cork cells lack chloroplasts.
- Both epidermal cells and cork cells prevent the air and water loss from the internal structures of the plant.
- Both epidermal cells and cork cells secrete water-repellent substances.
Difference Between Epidermal and Cork Cells
Definition
Epidermal Cells: Epidermal cells refer to the outermost layer of cells on the primary plant body.
Cork Cells: Cork cells refer to the cells of the outermost layer of the secondary stem and root.
Type of Growth
Epidermal Cells: Epidermal cells occur during both primary and secondary growth of the plant.
Cork Cells: Cork cells occur during the secondary growth.
During Primary Growth
Epidermal Cells: Epidermal cells cover the whole plant body during primary growth.
Cork Cells: Cork cells are absent during primary growth.
During Secondary Growth
Epidermal Cells: Epidermal cells are found in leaves and other immature parts of the stem and root during the secondary growth.
Cork Cells: Cork cells are found in the mature stem and root during the secondary growth.
Living Cells
Epidermal Cells: Epidermal cells are living cells.
Cork Cells: Cork cells are non-living cells.
Water-repellent Substances
Epidermal Cells: Cutin is the water-repellent substance secreted by epidermal cells.
Cork Cells: Suberin is the water-repellent substance secreted by cork cells.
Number of Layers
Epidermal Cells: Epidermal cells consist of a single cell layer.
Cork Cells: Cork cells consists of multiple layers of cells.
Occurrence
Epidermal Cells: Epidermal cells are found in all type of plants.
Cork Cells: Cork cells are found in woody and many herbaceous dicots, gymnosperms and some monocots.
Conclusion
Epidermal cells and cork cells are two types of cells in the outermost layer of the cells. Epidermal cells are arranged in a single layer to cover the whole plant body during primary growth. Cork cells are produced by the cork cambium during secondary growth of plants. Both epidermal cells and cork cells contain water-repellent substances to prevent the water loss from the plant body. The main difference between epidermal and cork cells is the occurrence of each type of cells in the plant body.
Reference:
1.“Plant Epidermis: Function & Structure.” Study.com, Available here.
2.“Galleries | Cork Cells.” Nikon’s MicroscopyU, Available here.
Image Courtesy:
1. “Leaf Tissue Structure” By Zephyris – Own work (CC BY-SA 3.0) via Commons Wikimedia
2. “Woody Dicot Stem: Secretory Ducts and Cells in One Year Sambucus” by Berkshire Community College Bioscience Image (Public Domain) via Flickr
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