What is the Function of Leaves?

The leaf is an important part of a plant because it produces food for the other parts of the plant through photosynthesis. For in depth knowledge of its functions, dive into the article.
JAN23 What is the Function of Leaves
By machines from Unsplash+

Plants are autotrophs and hence are the primary producers of this earth. Without them, it’s unimaginable for any living being to survive. They produce food for all the other consumers. And just like plants are necessary as a primary food source for the world, leaves are also eminent for plants. Without leaves, the being of a plant is incomplete. But do you know why? Why leaf is an important part of a plant? What is the function of leaves? If not, then keep reading to find out.

1. Why are Leaves called Leaves?

Some people believe that leaves are called leaves because they leave the trees but there aren’t any clear pieces of evidence that support this theory. Leaves are the plural of the leaf. The word leaf is derived from the old English word ‘lēaf which is of Germanic origin and has relation to the German Laub and Dutch Loof. These words are used to address the green outgrowths from the stem of vascular plants. And this is a reason why leaves are called leaves. After this, it’s necessary for you to also learn about the types of leaves in the following para. (See What are Examples of Flowering and Non Flowering Plants?)

2. What are the Types of Leaves?

Before you know what is the function of leaves, note that based on broad division, there are two types of leaves- simple and compound leaves. These categories are then further classified into different groups on the basis of their arrangement on the stem, size, shape, leaves on non-flowing plants and flowering plants, and other physical attributes.

In a simple leaf, a single lamina is attached to the main stem by a petiole. This type of leave cannot be further divided into leaflets or any smaller unit. For example, Hibiscus, Mango, Guava, etc. On the other hand, in compound leaves, the leaf blades are further divided into two or more leaflets that are connected to the stem via the petiole. For example, Rose, Neem, Poison Ivy, etc. The compound leaves are further classified into Pinnately Compound Leaf and Palmately Compound Leaf.

Pinnately Compound Leaf- In a pinnately compound leaf, the leaf midrib is divided into many leaflets, and all these leaflets are connected by a common axis.

These are the further types of the pinnately compound leaf: 

  • Pinnate: It is a compound leaf with an axis on each side of its midrib.
  • Unnipinnate: It is a compound leaf with leaflets on each side of the axis. For Example, Azadirachta indica.
  • Bipinnate: In this type of leaf, the central axis produces a secondary axis bearing the leaflet. For example, Mimosa pudica.
  • Tripinnate: In this type of leaf, the secondary axis produces a tertiary axis that bears leaflets. For example, Moringa.
  • Decompound: These are leaves with more than three pinnate.
  • Paripinnate: These are leaves with terminal leaflets. For example, Cassia.
  • Imparipinnate: These levees have an odd terminal leaflet. For example, peas.

Palmately Compound Leaf- The leaf that has its leaflets attached at the tip of the petiole is called a palmately compound leaf.

It can be further differentiated into: 

  • Unifoliate: These are the leaves with only one leaflet. For example, Citrus.
  • Bifoliate: These are the leaves with two leaflets. For example, Balanites.
  • Trifoliate: In this type of leaf, three leaflets emerge from the same point. For example, Oxalis.
  • Quadrafoliate: In this type of leaf, four leaflets emerge from the same point. For example, Marsilea.
  • Multifoliate: In this type of leaf, many leaflets emerge from the same point. For example, Bombax.

3. What are Leaves Made of?

Leaves are made up of three major parts- the petiole, base, and blade. The petiole connects the leaf blade to the meristem or stem of the plant. The base is the region of the leaf blade that is connected to the petiole. The blade is usually the largest part of the leaf and is sometimes also referred to as the lamina. After understanding this let’s see what is the function of leaves. (See Why are Minerals Essential in Photosynthesis?)

4. What is the Function of Leaves?

JAN23 What is the Function of Leaves 1
By Charlie Harris from Unsplash+

After going through the composition of leaves, let’s further read what is the function of leaves. The functions of leaves are as follows:

  • Performing Photosynthesis: The most important function of the leaf is to produce food via photosynthesis and then transfer this food to other parts of the plant using phloem tissue. Leaves contain chloroplasts which have a pigment called chlorophyll. This pigment is necessary for photosynthesis.
  • Storing food: Some plants modify their leaves to also produce food. These modifications are mostly seen in Xerophytic plants as they generally have succulent leaves.
  • Helping the plant breathe: A leaf contains guard cells in its epidermis layer. These cells control and regulate the small pores on the undersurface of the leaves. These pores are referred to as stomata. The stomata are responsible for regulating the water in and out of the cell. They are also responsible for exchanging gases through the epidermis.

5. Why Leaf is an Important Part of a Plant?

After you are aware of what is the function of leaves, let’s try to understand the importance of a leaf as a plant part. The leaf is an important part of a plant because it produces food for the other parts of the plant through photosynthesis. The leaves have a pigment called chlorophyll which is necessary for photosynthesis. The epidermis layer of the leaves contains guard cells which are responsible for controlling and regulating small cells on the undersurface of the leaves. These small pores are called stomata. These pores regulate water in and out of the cell. They also exchange gases through the epidermis. (See How is Photosynthesis Considered Endergonic?)

6. How does a Leaf Make Food?

Now that you know what is the function of leaves and why leaf is an important part of a plant, let’s check out the role of the leaf in food making. Through the process of photosynthesis, leaves make food for the plant. In this process, the plants use sunlight to produce food. This process is required to make a kind of sugar form called glucose. Glucose is essential for a plant’s survival and development. Apart from sunlight the plant also needs water and carbon dioxide to produce glucose. The carbon dioxide enters the plant’s leaves through stomata which are microscopic pores. On the other hand, the plant’s stem and root carry water to the leaves.

The process of photosynthesis occurs inside chloroplasts which are small structures inside the cells of plant leaves. These small structures contain a pigment called chlorophyll which reflects green light and absorbs red as well as blue light.

During the process of photosynthesis because of oxidation the water loses electrons and turns into oxygen gas. At the same time, the carbon dioxide goes through reduction, gains electrons, and is then converted into glucose. 

7. How do Leaves help Plants Grow?

What is the function of leaves? The main job of a leaf is to produce nourishment for a plant. For this, the leaves use sunlight for energy to take apart water from the ground and carbon dioxide from the air. They then use a portion of the carbon dioxide and water to make sugar (glucose). This process of food-making is called photosynthesis. Once the glucose is produced through this process, the leaves use phloem (a special structure that runs parallel to the Xylem) to transport the glucose down the plant.

To support plant growth, the glucose is transported to the shoots and roots of the plant. In this way, leaves help plants to grow. After this, let’s see why leaves are important to other living things. (See Plants Store Food in the Form of?)

8. How Leaves are Important to Other Living Things?

Plants are primary producers and all living beings depend on plants directly or indirectly for their food source. Without leaves, it is impossible for plants to undergo photosynthesis and make their own food. The leaves use sunlight for energy to take apart water from the ground and carbon dioxide from the air. They then use a portion of the carbon dioxide and water to make sugar (glucose).

The process of photosynthesis occurs inside chloroplasts which are small structures inside the cells of plant leaves. The oxygen removed from the atmosphere by animal and plant respiration as well as by combustion is also replaced by the oxygen liberated by the green leaves. These are the reasons why leaves are important to other living things.

9. What is the Function of Each Part of a Plant?

The function of each part of a plant is as follows: 

  • Root: This underground part pulls the water and minerals from the ground for the plant. It expands itself within the ground for better water absorption. It also creates better stability for the plant by acting as an anchor. It fuses the development of plant ad stock reserves of food material. It stores food that binds the soil together.
  • Stem: This part is present above the ground and usually it bears leaves, flowers, and fruits. It is the plant’s support system. It is responsible for distributing minerals and nutrients from the plant to the leaves. It assists in asexual dissemination and also shields the plant. The stems grow upwards to allow the leaves to reach the sunlight which is essential for photosynthesis. Some stems also develop thorns to protect plants from animals.
  • Leaves: It performs one of the most important functions in the plant. So, what is the function of leaves? It contains chlorophyll which is a key ingredient for photosynthesis. The leaves produce food for the plant vias photosynthesis. They are also responsible for transpiration. The leaf veins allow the flow of nutrients and water. Additionally, leaves also assist in the plant reproduction process.
  • Flowers: These parts of the plant are bright and beautiful. They are involved in making food. There are male and female parts in a plant and these parts work collectively to produce seeds by fertilizing the plant.
  • Fruits: These are the products of plant reproduction. They act as a protective layer for seeds. Their primary role is to allow the plant to reproduce by dispersing seeds.
  • Seeds: They are mostly found in fruits and are the main agents of reproduction. A seed aids in the germination of a new plant. 

Plants are essential for the proper functioning of the world. Without them, you wouldn’t be breathing right now. The most important part of the plant is the leaves. They are responsible for performing photosynthesis, storing food for the plant, and helping it breathe. Apart from the leaves, the other parts of the plants also have other important functions to perform. (See What is Importance of Soil to Plants?)

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