Exploratour - Life on Earth

Autumn Foliage
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Image courtesy of Corel Photography

Kingdom Plantae contains nearly 300,000 different kinds of plants. Although this does not make it the largest kingdom, many might argue that it is the most important one.

In the process known as "photosynthesis", plants use the energy of the Sun to make food and oxygen. This complex chemical reaction provides nearly all the oxygen in Earth's atmosphere and all the food required by living things. Although some protists and bacteria are capable of performing photosynthesis, plants do most of the photosynthesis on Earth.

The ancestors of plants first appeared in the seas nearly 700 million years ago. Another 265 million years passed before the first plants appeared on land. These early land plants looked very different than the plants you're familiar with today. In fact, many of them didn't even have roots, stems, or leaves! Since then, plants have taken on a variety of forms and are found in most places on Earth.

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