- Oxygen production
- Remove carbon dioxide (other waste for plants)
- Decrease the surrounding temperature
- Food production
- Source of medicine
- Provide fiber
- For making utensils
- Home construction material
- To record history and other writings
- Tobacco products.
Introduction of Leaves
Leaves are greenish organs of plants distributed on the upper parts of the trunk. They are green due to the presence of a pigment named chlorophyll.
Unlike other parts of the plant, they are highly active.
This shows their active role in plant physiology. Both the formation of leaves and their shedding is also essential for the plant.
Leaves are tender, flat and flexible in structure. They tend to get erect in the day and lie down drooped in the night.
Just like many uses of plants, there are also many uses of leaves.
Uses of leaves in our life
1. Oxygen production: Oxygen is vital for life. When we breathe oxygen, it enters our body cells and tissues and generates energy from glucose. This energy helps us perform all our daily work.
Air has 21% oxygen. And when all the animals breathe daily and release out CO2, the oxygen ratio can go down leading to suffocation. But green leaves release oxygen during the process of photosynthesis. Thus they help to maintain the proper oxygen ratio in the air.
2. Removes excess carbon dioxide: Besides the consumption of oxygen, we also leave out CO2 during expiration. This release is also further added up when we burn some wood or fossil fuels. So this can drastically enhance the carbon-dioxide levels in the air which could be harmful to all the animals on the earth.
Interestingly, plant leaves take in CO2 as a part of photosynthesis.
During the process, they take up carbon-dioxide along with water to help in the formation of sugars like glucose in the presence of sunlight. Thus they take up large volumes of CO2 from the air and help in bringing down its levels. Since CO2 is one of the greenhouse gases, its increase can enhance global warming. So plant through leaves can keep a check on carbon-dioxide.
Help excrete the waste. Besides CO2, leaves also help to accumulate the plant waste in them. The secondary metabolites which are toxic to plants are accumulated in leaves. When the leaves are old and dry, they are shed off. Thus waste metabolites like alkaloids, tannin, glycosides are expelled by shedding. Hence, plants shed many leaves every year.
3. Decrease the temperature: In general, the presence of green trees is considered necessary for low temperatures during summers. This is true as plants minimize greenhouse gas effects. But the other mechanisms involved are through leaves of the plants.
Leaf pigments absorb light from the sun and store it in the form of chemical energy. Thus the light reflected in space from plants is low. Also, leaves have large amounts of stomata that expel the water by the process called transpiration. This sending of water into the air also reduces the temperature.
Thus leaves help to lower the atmospheric temperature around us.
3. Food production: Leaves are involved in food production. They prepare sugar which is stored in fruits, seeds and tuber (potatoes) of plants. Also, some leaves become succulent and eatable. There are also many green leafy vegetables which are rich in iron and can be used as part of our food. There are some thousands of edible leaves which can be taken as a part of our diet.
Hence we can see leaves in all the ecosystems. Many insects, cattle depend on leaves for food. Similarly, in the marine ecosystem, small fishes and big mammals like sea buffalo, whales depend on leaves for food.
4. Medicine: Medicine is one of the important uses of leaf. They are the biggest source of medicine from natural resources. Many leaves like that of digitalis, vinca, aloe are excellent sources of medicine.
Digitoxin from the leaves of digitalis plant is used in case of heart failure, vincristine from vinca plants is a drug for the treatment of cancer, aloe leaves have moisturizing properties which help to heal the dryness of the skin.
5. Commercial tobacco: Tobacco which is widely used in cigars and other smoking and chewing products is obtained from the leaves of tobacco.
6. Fiber: Few leaves are the source of good quality fiber for manufacturing ropes and threads. Examples of the plants whose leaves are used for the purpose include hemp, Henequen, sisal, abaca, etc. These fibers are hard and coarse.
7. Dyes: Leaves are also sources of colors and dyes. Unlike synthetic ones, these are obtained from nature, so the process is called as eco-dyeing or eco printing. Many leaves like
Eucalyptus: Dark Tan
Coneflower: Brownish green
Fennel leaves: golden brown etc. are the plants whose leaves can be used for extraction of dyes.
8. Home construction: This is another prominent use of leaves to man. Especially the large ones are used for house construction. These are specifically used for a rooftop for small huts or even houses made of mud.
They keep the house cool as they are bad conductors of heat. But, the roof is not stronger like the reinforced cement concrete. So, they can be blown off by heavy winds. Further, they tend to catch fire which is another risk.
9. Small Utensils: Though not large ones, leaves are traditionally used in making small utensils like cups and also used as plates. They are nature-friendly, disposable and also have no untoward effects on humans.
Leaves are knitted into cups or plates and dried latter in the sun, to make them slightly harder. Then they are used for serving dishes, eating, drinking, etc.
Leaves used for producing utensils are
- Banana leaves,
- Palm leaves
- Areca etc.
10. Communication and records: Modern man has books, software documents to store his data and records. But, in the past before the availability of paper, palm leaves were used for writing scripts and other literature.
They were used for quite a long time in this manner in different parts of the world. They are said to be used since 5th century BC onward. These are called palm leaf manuscripts. Interestingly these palm leaf records can be found without damages.
Importance of Leaves in Plants
Leaves are important for trees and plants too. They not only help in food production as mentioned before but also has other uses like
- Transpiration (heat management)
- Movement of sap from roots to the top of trees
- Protection from herbivores
- Survival of plants in a drought.
- Expulsion of waste material from the plant body.
This is a process of removal of water content from the trees. It helps to minimize the heat in the plant body. This transpiration occurs through the stomata present on green leaves. Stomata are the apertures present on green surfaces of a plant. Since leaves have a number of stomata, maximal transpiration occurs through them. Moisture is sent out of the plant body during hot weather like summers in order to remove excess heat from the plant body.
Movement of sap
Plants do not have a circulatory system from the movement of food and other matter in their bodies. For this, the movement occurs downward under the influence of gravity. It also occurs upwards due to transpiration. Since moisture is lost at the top from leaves, there is negative pressure created in the trunk for the movement of sap from roots to the tip of trees. This way leaves help to maintain the upward movement of sap.
Protection from herbivores
In the case of the plant surviving in the desert or extreme water scarcity, leaves are modified to have thorns. These thorns are pricky and prevent the herbivore animals from grazing on them.
Storage of food and water
Since water is scarce in deserts, desert plants have succulent leaves. When cut, they ooze out the sticky substance which has water and other essential food materials needed by the plant. Due to this arrangement of reserving water in leaves, desert plants can survive for a long time.
Expulsion of waste material
Plants also do not have separate excretory organs. Their waste is collected into dead plant cells and also leaves.
Leaves shed at the regular time interval and new ones are formed in the plant. Plant during its course of living generates nitrogenous waste and is stored as alkaloids in the leaves. When leaves are shed off, this waste is removed off from the plant.
See more facts about plants.
For Ecosystem: They maintain oxygen levels, decrease temperatures and act as a source of food for other animals.