Dermal tissue is a thin layer of cells covering the soft parts of a plant.
Learn more about the dermal tissue of a plant, and take a short quiz at the end of this lesson.
What Is Dermal Tissue?
When you think of the parts of a plant, the leaves, stem, and flowers probably come to mind. Trees may bring to mind a trunk, branches, and leaves or needles.
However, would you think of skin as a part of a plant? Probably not.Skin is clearly an important and well-known part of a person or animal. But surprisingly, plants have an outer layer known as dermal tissue that is essentially their skin. This layer is also known as the epidermis, which you may notice has the same name as our very own outer layer.Dermal tissue is found covering the younger primary parts of a plant. These include leaves, roots, stems, flowers, fruits, and seeds. Plant parts that become woody no longer have dermal tissue as their outer layer because it is replaced by periderm, or cork.
Just as our own skin serves to protect our bodies, the dermal layer of a plant has the same function. We will discuss this a little later.If we were to take a close look at our own epidermis, we would find a very thin layer of skin that is tough yet flexible. Zooming in on dermal tissue of a plant, we find a similar structure. In fact, this epidermis is so thin that it is only one cell-layer thick.
It is mainly composed of flattened epidermal cells, and some cells are specialized for specific functions.
Like our own skin, the dermal layer of a plant is its first line of defense. It protects against damage to the plant itself. In addition, the epidermal cells of a plant are closely packed together to create an effective barrier against potentially harmful intruders, like fungi.On leaves, we find a waxy coating secreted by epidermal cells. This coating is called the cuticle. The cuticle helps water from constantly evaporating from the leaves.
You can see evidence of this cuticle on many plants after a rainstorm. Water forms as balls on leaves, demonstrating its inability to soak into the leaf because of the waxy cuticle.Also, within the dermal layer are specialized cells that are responsible for allowing gas exchange to occur. These allow some water to evaporate. In order to understand how these cells work, we will take a closer look at a leaf.
Invisible to the naked eye, there are microscopic openings on a leaf known as pores. Just like pores in our own skin that allow sweat and oils out, those in the dermal layer are the openings that allow gases and water to pass through. Each pore is flanked by two bean-shaped cells called guard cells.
Together, the pore and guard cells make up what is known as a stomata.Since they are the only openings in the epidermis, stomata regulate what is able to pass through the dermal layer. Gas exchange occurs through these tiny openings, which makes it possible for the plant to make food and release waste.As humans, we breathe in oxygen through our nose and mouth and exhale carbon dioxide as a waste product. In plants, this process is the opposite. Plants take in carbon dioxide in order to make food through photosynthesis.
They release oxygen as a waste product. It is obvious that a plant cannot accomplish this through a mouth or nose, and this is where the stomata come in handy.When the stomata are open, carbon dioxide is able to diffuse into the leaf. Oxygen is released this same way. However, water is also able to escape through open stomata.
For this reason, most of these tiny openings are found on the underside of the leaf so the plant does not lose too much water through evaporation.
Extensions of the Dermal Layer
There are other adaptations of the dermal layer that help the plant immensely. Some of these include tiny hairs rising from the epidermis and roots of the plant. Epidermal hairs help to prevent excess water loss by decreasing airflow over the surface of the dermal tissue.
Root hairs are tiny extensions of the root epidermis. They provide extra surface area and are instrumental in absorbing ions and water from the soil.
Let’s review. The dermal tissue of a plant is the extremely thin outer layer of the soft parts of a plant. It is also known as the epidermis.
Epidermal cells are flattened and very close together. Stomata are found in the dermal tissue. These are tiny pores flanked by two guard cells. Stomata regulate the flow of gases in and out of the leaf, as well as the escape of water. Adaptations of the dermal tissue include epidermal hairs and root hairs.
This video lesson on dermal tissue should give you the tools necessary to:
- Discuss the presence of dermal tissue on plants
- Specify the functions of dermal tissue
- Detail the adaptations of the dermal layer that can help plants