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Why is grass green?

Close-up view of blades of grassClose-up view of blades of grass Grass is a kind of plant, and the blades of grass that make up a lawn or a meadow are the leaves of grass plants growing closely together. They are often cut short by a lawnmower or grazing animals. But if they are allowed to grow, you would see emerging from the long, narrow leaves their hollow stems, called culms, topped by flowers. Like many other plants, grass produces a bright pigment called chlorophyll in its leaves. Chlorophyll looks green because some of the colours that make up sunlight—red and blue—are absorbed (soaked up), while green is reflected. (Although sunlight looks white, it is really made up of several different colours, the colours of the rainbow.) When the green reflected light reaches your eyes, you see grass as green.

Chloroplasts inside leaf cells (greatly magnified)Chloroplasts inside leaf cells (greatly magnified)

Chlorophyll is a chemical found in a plant’s leaves. It plays a vital role in the way a plant makes its food. Chlorophyll has the ability to store the light of the sun. The plant uses this energy to power a chemical reaction that takes place in its leaves, known as photosynthesis. In this reaction, water, which is taken up from the soil, and carbon dioxide, taken in from the air, join together to form glucose, a type of sugar that is packed full of energy in chemical form. The plant uses this sugar to power its life activities.

A plant’s leaves are usually broad and flat so that as much light as possible falls on them. Inside the cells in the leaf’s upper surface there are a large number of tiny blobs or discs, called chloroplasts. It is these that contain the chlorophyll.

Unlike the leaves of other plants, grass blades grow at the base and not from the tip. This allows grasses to be grazed or mown regularly without damage to the plant.

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