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Why are Plants Green?

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Green Plants: An Introduction

Green plants are also known as autotrophic plants because they are reported to contain a green-coloured photosynthetic pigment called chlorophyll, which is found in the chloroplast of plants. Plants are called photoautotrophs because they are capable of producing their own food through photosynthesis. The food synthesised by plants is stored in the form of starch. Green plants absorb carbon dioxide and release oxygen. Thus, plants help us to survive by providing oxygen to breathe in.

Why are Plants Green?

The integral part of a plant is the leaves, along with the other parts like the stem and root. Leaves are capable of performing photosynthesis with the aid of a primary pigment, chlorophyll which imparts green colour to the plants. The process of photosynthesis involves the conversion of light energy to chemical energy.

Plants have different pigments with different colours. The green pigment is known as chlorophyll which absorbs light. There are two types of chlorophyll, one is chlorophyll A which is the main pigment that takes part in the electron transport, and the other is chlorophyll B, which is the accessory pigment. They are reported to absorb light from 400-650nm.

Chlorophyll A can absorb blue light of wavelength 430 nm and red light of wavelength 662 nm. However, it is unable to absorb green light of wavelength 550 nm and thus reflects the green light. Due to the reflection of the green colour, the leaves on the plant come out green, and that is why the leaves are green.

Colourful Leaf Plants

The most colourful times of the year are spring and summer. Bright-coloured leaf plants blossom, and a sea of colour appears everywhere. There are different types of colourful leaf plants. The examples are discussed below.

The first is the hostas. This popular garden plant has large green leaves with thick white borders with numerous patterns and textures. The ‘Fire Island’ variety of hostas has luminous yellow leaves. The second is the Coleus which has interesting textures and colours ranging from reds, pinks, and yellows, to mixes of brilliant hues. They love the sun, and it appears bright during summer.

The Black Dragon variety has deep burgundy leaves with ruffled edges. Amaranthus Tricolour grows throughout the year; they appear in yellows, reds, and orange colours. It grows well during summer. The coral bells are low-growing shrubs that have purple to orange leaves.

Why are Green Plants Called Producers?

Green plants are called producers because they have the capability to produce their own food in the presence of sunlight through the process of photosynthesis. Green plants can prepare food from simple inorganic substances like carbon dioxide and water. During this process, energy in the form of glucose is released, which is used by the plants for survival, growth and reproduction.

Green plants are called autotrophs as they can manufacture their food from raw materials present in the surroundings like carbon dioxide and water. During the process of photosynthesis, plants consume carbon dioxide and release oxygen gas which is consumed by us. The steps of photosynthesis are discussed below.

Step 1: Absorption of light energy from the sun by chlorophyll.

Step 2: Conversion of light energy to chemical energy.

Step 3: The splitting of a water molecule into hydrogen and oxygen.

Step 4: Carbon dioxide is reduced to glucose.

Why are Leaves Green?

The green pigment present in leaves is chlorophyll which is contained in the thylakoid membranes of chloroplasts. There are five types of chlorophylls: chlorophylls a, b, c, and d, and a related molecule bacteriochlorophyll that is exclusively found in prokaryotes. It is present in the plasma membrane of bacteria.

The structure of chlorophyll molecules contains a hydrophobic tail that is inserted into the thylakoid membrane and a porphyrin ring head that is mainly responsible for absorbing light. Chlorophyll a is the main component, and the rest are accessory pigments. The accessory pigments help in absorbing a broader range of wavelengths so that more energy is captured from sunlight.

Interesting Facts

Green plants are called photoautotrophs because they can make their own food through the process of photosynthesis, which converts carbon dioxide and water in the presence of light to oxygen and energy. Chlorophyll assists this process by absorbing light energy.

Important Questions

1. What is the importance of green plants?

Ans: As the primary producers of the ecosystem, green plants are involved in producing food for consumers. Green plants are essential for maintaining the planet's carbon dioxide and oxygen equilibrium.

2. What are carotenoids?

Ans: Plants produce the yellow, orange, and red pigments known as carotenoids. The carotenoids alpha-carotene, beta-carotene, lutein, zeaxanthin, and lycopene are the most prevalent.

Key Features

  • The leaves of the plants appear green because of the presence of the green pigment Chlorophyll.

  • Chlorophyll plays a significant role in photosynthesis by absorbing light energy from the sun. Chlorophyll A mainly absorbs light strongly within the blue and red portions of the spectrum.

  • The green leaves can absorb light of all wavelengths except the wavelength of green light, i.e. the wavelength of 550nm. This green wavelength of light is reflected by the plant.

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FAQs on Why are Plants Green?

1. How many pigments are there in plants?

There are three types of pigments present in the leaves of plants. Their presence determines the colours of the leaves. Some examples are anthocyanins, carotenoids, and betalains.

2. What are anthocyanins?

Anthocyanins are one of the accessory pigments of plants that can be blue, red, or purple in colour. It is reported to be present, especially in flowers, fruits, and tubers. Anthocyanin appears red in acidic conditions and blue in alkaline conditions.

3. What are consumers and decomposers?

The consumers intake food by consuming the producers. Decomposers, on the other hand, have the capability of breaking down dead organisms to release inorganic molecules into the environment.

4. Name the plant that has multi-coloured leaves.

The caladium plant has multicoloured leaves. It is reported to grow well in hot and humid conditions. The leaves are larger, and the colour is a combination of green, red, white, and pink.