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through the treetops. Sunlight flickers through the rustling leaves. This forest is full of life and sound. This morning, a new sound comes from


B


the forest. It begins as a faint buzzing. The buzzing grows louder and louder. Suddenly, a man flies high over the


treetops. Meet Mark Olson, the flying botanist. He studies how tree leaves gather and use sunlight. Olson doesn’t look at leaves from the


ground, though. Instead, he straps a winged machine to his back. The buzzing comes from his paraglider. He zips over the treetops and looks down at them. That way, he gets a bird’s eye view of leaves.


Leaves at Work Olson glides to the ground. He lands near the trees he’s been studying. T ey’re moringa trees. T ese trees fascinate him. People use their leaves and roots for food, and their bark for medicine. Some people call them miracle trees. To


Olson, the miracle is what happens inside each leaf every day. Like all green plants, trees make their


own food. Leaves use the sun’s energy to start a process called photosynthesis. It mixes water with carbon dioxide. T is makes glucose, a kind of sugar. Plants use some of the glucose for food. T ey store the rest for later. Photosynthesis is as important to us as


it is to the tree. It recycles carbon dioxide. Too much can harm our environment. T is process also makes the oxygen we breathe. T is keeps life on Earth going.


20 oxygen is released


irds squawk and chirp as they flit


Using Sunlight Olson looks up at the leaves of one large tree. T e sun makes him squint. It also reminds him that the tree’s leaves are hard at work, even if he can’t see it. T e sun’s warmth makes tiny pores on


the leaves open. Carbon dioxide from the air goes into the pores. Inside each leaf, chlorophyll soaks up the sunlight. T e tree’s roots take in water and


minerals. Plant tissues called xylem carry water up the trunk. T e water travels along branches and into each leaf. T e leaves make glucose. T en phloem, or tissues in the inner bark, carry this sugar to the rest of the tree. Each leaf makes only a tiny amount


of food. So a fully grown moringa needs thousands of leaves to keep it alive.


PHOTOSYNTHESIS


A leaf turns the sun’s energy, water, and carbon dioxide into food and oxygen.


light energy enters leaf


water enters leaf


sugar leaves leaf


carbon dioxide enters leaf


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