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A World That Turns Gold

Every autumn, something quiet and wonderful happens to trees. Green leaves slowly turn yellow, orange, and bright red. Whole forests seem to catch fire with color. Each year this change happens right on time. You can rake the fallen leaves into crunchy piles. But why do leaves change color at all? The answer is hidden inside every single leaf.

Think about how a maple tree looks in October. In June its leaves were a plain, steady green. Now they burn with red, gold, and orange. The tree did not paint itself with new colors. Most of those colors were there all along.

The Green Hidden in Every Leaf

Leaves are like tiny kitchens for the whole tree. They make food using sunlight, air, and water. Scientists call this special food-making work photosynthesis. It is a long word for a simple idea. A green helper called chlorophyll does most of the work. Chlorophyll catches sunlight and turns it into sugar. This sugar is the food that helps trees grow.

Chlorophyll also gives every leaf its bright green color. All summer long, leaves are packed full of it. Green is the color of a busy, healthy leaf. That is why trees look so green in summer.

Trees cannot buy food from a store like we do. They must make every bit of their own food. That is why healthy green leaves matter so much.

Colors That Were Always There

Here is a surprise that many people miss. Yellow and orange colors hide in leaves all year. These hidden colors come from pigments called carotenoids. A pigment is simply something that gives color. The same pigments make carrots orange and corn yellow. You have seen these colors on your dinner plate.

So why can't we see these colors in summer? The strong green chlorophyll simply covers them up. The yellow and orange wait quietly underneath it. They stay hidden until the green begins to fade. Birch and aspen trees glow bright gold this way.

Shorter Days Send a Signal

So what makes the green chlorophyll fade away? The secret is the changing amount of daylight. Sunlight works like a clock and calendar for trees. In autumn, the days slowly grow shorter and cooler. The nights become longer, and the air turns cold.

Trees can feel these changes, just like we can. Less sunlight tells the tree that winter is coming. So the tree slowly stops making new chlorophyll. The old green color breaks down and fades away. As it fades, the hidden colors finally appear. At last, we can see the yellow and orange.

This slow change is really the tree getting ready. It is packing up before the long, cold winter.

The Bright Red Surprise

But where does the deep red color come from? Red is a little different from the other colors. It is not usually waiting inside the leaf. Instead, the tree makes it fresh each autumn.

The tree makes a red pigment called anthocyanin. Leftover sugar trapped in the leaves helps make it. Warm sunny days and cool nights make more red. That is why some autumns look brighter than others. Maple trees are famous for their fiery red leaves. On a sunny hillside, the reds can look amazing.

Letting Go

After the color show, the leaves are ready to fall. The tree grows a tiny seal where each stem joins. This tiny seal slowly cuts the leaf away. Soon the leaf drifts gently down to the ground.

Not every tree loses its leaves in autumn. Pine and fir trees keep their thin green needles. We call these trees evergreens for that reason. Their waxy needles can survive the cold winter. That is why we use them as Christmas trees.

Dropping its leaves helps a tree save water and energy. The bare tree rests all winter, safe and quiet. In spring, fresh green leaves will grow again. So autumn colors are not really an ending. They are part of the tree's yearly rest. Next fall, watch the leaves change close up. Try to notice which trees change color first. Now you know the secret they have been showing.