Elizabeth, a Licensed Massage Therapist, has a Master's in Zoology from North Carolina State, one in GIS from Florida State University, and a Bachelor's in Biology from Eastern Michigan University. She has taught college level Physical Science and Biology.
What is a Plant Epidermis?
You may have heard at some point that your skin is the largest organ in your body. Besides being large, your skin is very important because it protects everything underneath it from disease, temperature, and other physical damage that may occur.
Much like your skin, a plant has a tissue system, a group of cells that work together for a very specific function, that form the first line of defense against physical damage and disease. This tissue system is called the dermal tissue system, and it is the plant's outer protective coating.
The dermal system itself consists of a layer of tightly packed cells called the epidermis. On most plant stems and leaves, the epidermis is covered with a waxy coating called the cuticle, which helps prevent water loss through the epidermis.
Plant epidermis is unique because it is actually two different layers of cells: the upper epidermis and the lower epidermis.
Sandwiched in between these two layers are two other important tissue systems - the vascular tissue system and the ground tissue system. The vascular tissue system provides water and nutrient transport from the roots to other parts of the plant. The ground tissue system, also called the mesophyll, is specialized for photosynthesis, the process by which the plant converts sunlight into usable chemical energy.
But if the epidermis covers the mesophyll, how does photosynthesis occur here? The epidermis is actually interrupted by small pores called stomata. These openings allow the exchange of carbon dioxide and oxygen, which powers photosynthesis. Stomata are controlled by guard cells, which regulate the extent to which the stomata are open or closed.
Serving as a plant's skin, epidermis cells protect internal tissues from the outside world by creating a barrier. But the epidermis also serves a variety of other functions for plants.
When stomata open to exchange gases during photosynthesis, water is also lost through these small openings by evaporation. Plants do not like losing water, and the waxy cuticle of the epidermis helps minimize this loss, keeping plants from drying out.
The epidermis also helps protect plants from being eaten by animals and parasites. Many plants have thick hairs or spines that come from the epidermis, making it very unattractive to a hungry animal. Think of a cactus with its large spines. The danger associated with trying to access what's behind those spines likely makes that plant very unappealing to you!
Epidermal cells can also become very specialized, and since this layer of cells is exposed to the outside world, how they specialize can be significant. Both the color and texture of epidermal cells can help attract and keep pollinators. Epidermal cells may enhance the scent and color of a plant's flower petals, making them more attractive to pollinators. They may also specialize to form a landing surface that is less slippery, providing an area that is more stable for pollinators to stand on.
Though only a thin layer of cells, a plant's epidermis is a very important tissue system. The epidermis helps keep plants from drying out, and it protects against predation, physical damage, and disease. Much like your skin protects the delicate tissues and organs beneath it, a plant's epidermis creates a protective barrier between its internal parts and the outside world.
Plant Epidermis Terms
|Tissue system||a group of cells that work together for a very specific function, that form the first line of defense against physical damage and disease|
|Dermal tissue system||a plant's outer protective coating|
|Epidermis||a dermal layer of tightly packed cells|
|Cuticle||waxy coating that helps prevent water loss through the epidermis|
|Vascular tissue system||provides water and nutrient transport from the roots to other parts of the plant|
|Ground tissue system||also called the mesophyll; specialized for photosynthesis in which plants convert sunlight into chemical energy|
|Stomata||small pores that interrupt the epidermis|
Heighten your knowledge of the plant dermis as you review this lesson so that you can go on to:
- Discuss the composition of the dermal system
- Illustrate the structure of a plant's epidermis
- Highlight the functions of epidermis cells
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