Hello, Wonderers! Do you ever look around in autumn, amazed at the bright oranges, fiery reds, and golden yellows on the trees? It’s like nature’s own fireworks show! But have you ever wondered, why do leaves change colour? Let’s go and find out!
Why Are Leaves Green in the First Place?
In spring and summer, most leaves are a bright green because of something called chlorophyll. Think of chlorophyll as the leaf’s natural green “paint”—it’s a pigment that helps plants turn sunlight into food. Leaves are like tiny food factories, mixing sunlight with water from the ground and carbon dioxide from the air in a special process called photosynthesis. It’s chlorophyll that captures sunlight, letting photosynthesis happen, and it’s also what gives leaves their vibrant green colour.
So, Why Leaves Change Colour in Autumn?
When autumn arrives, everything changes. Days get shorter, nights get longer, and it starts to cool down. The tree senses that winter is on its way, which means less sunlight and water. To prepare, the tree stops making as much food, and the chlorophyll in the leaves begins to break down.
As chlorophyll fades away, it stops hiding the other pigments (colours) that were in the leaves all along. These hidden pigments begin to shine through, giving us the beautiful autumn colours!
Why Do Leaves Turn Different Colours?
Here’s where it gets really interesting. Different pigments in the leaves create those amazing autumn shades:
• Carotenoids: These pigments make the yellow and orange colours. Carotenoids are always in the leaves, but we don’t see them until the green chlorophyll fades away. You can also find carotenoids in foods like carrots (a good way to remember the word!), squash, and tomatoes, as well as green veggies like kale and broccoli!
• Anthocyanins: These pigments are responsible for the red and purple hues in some leaves. Unlike carotenoids, anthocyanins are made only in autumn, as the days get shorter and cooler. Scientists think anthocyanins might help protect the leaf as it prepares to fall from the tree. You’ll also find anthocyanins in red, purple, and blue foods like berries, aubergines, and red cabbage.
• Tannins: These are the pigments that turn leaves brown. Tannins don’t help the tree make food; they’re just the leftover parts of the leaf that remain when all the other pigments have broken down. You can also find tannins in tea, nuts, and chocolate—they’re what give these foods their slightly bitter taste. So, the next time you eat a piece of chocolate, you can remember the tannins in autumn leaves!
Why Do Trees Drop Their Leaves?
In cold places, it would be tricky for trees to keep their leaves healthy all winter. Leaves need sunlight and water to survive, but in winter, sunlight is scarce, and the water in the ground often freezes. So instead of trying to keep their leaves, many trees let them go and “rest” until spring. By shedding their leaves, trees also save energy and protect themselves from the weight of heavy snow, which could break their branches if they were still covered in leaves.
Fun Facts to Remember:
Not all trees change colour: Trees that stay green all year, like pine trees, are called evergreens. They have special leaves or needles that can survive winter.
Weather affects the colours: The brightness of autumn colours can change each year! Warm, sunny days and cool nights make the brightest reds, while cloudy, rainy weather can make the colours look softer.
So, the next time you see those bright reds, oranges, and yellows on the trees, you’ll know it’s all thanks to chlorophyll fading, carotenoids and anthocyanins coming through, and the tree getting ready for a cosy winter. Nature sure is incredible, don’t you think?
Try This: Press Your Favourite Autumn Leaves!
Want to keep a piece of autumn magic with you all year? Here’s a fun way to preserve those colourful leaves by pressing them. Follow these steps to make your very own leaf collection!
You’ll Need:
Freshly fallen leaves (find different shapes and colours for extra fun!
A heavy book (like an old dictionary or large notebook)
Parchment or wax paper
Extra heavy books or weights
Steps:
Gather your leaves: Head outside and collect a few colourful leaves. Make sure they’re flat, clean, and dry.
Prepare your pressing book: Open the heavy book and place a piece of parchment or wax paper on one of the pages.
Arrange the leaves: Place each leaf flat on the parchment paper, then cover with another piece of parchment. Carefully close the book over the leaves.
Add weight: To help press the leaves even more, stack a few heavy books or weights on top.
Wait patiently: Leave your leaves in the book for about one to two weeks. During this time, they’ll flatten and dry out completely, keeping their autumn colours.
Enjoy your leaf collection: Once pressed, you can use your leaves to make bookmarks, decorate cards, or simply keep them as part of a special autumn collection!
So get outside, find those amazing colours, and see if you can preserve the beauty of autumn! It’s a perfect way to enjoy autumn’s beauty all year long.
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