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Biological Environment > Seed Plants |
Earth Earlier Earlier 300 Million Years ago Later Earth After Plants Later |
This site tells the story of the history of the universe. Click Earlier and Later to follow the story. Note: Many facts have been simplified to make them easier to understand. |
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Dry land turned green when plants evolved from ferns able to reproduce without surface water. They did this by carrying their own copies of the wet soil with them. The egg was held near a little damp growth on the plant. The sperm was carried to it in a small grain called pollen which was blown by the wind. When pollen landed on the damp growth it could grow like a small prothallus. The sperm in the pollen fertilized the egg while it was still on the plant.
Once the egg was fertilized it developed into a seed, still on the adult plant. A seed is a baby plant wrapped up in a hard protective case. It waits for the right conditions (usually spring) before growing. Seed plants had thin needle-like leaves. They began to replace ferns around 300 million years ago and gradually spread over most of the land. The best known seed plants alive today are the conifer trees such as pine, spruce and larch. They are important to humans because they give us softwood timber for building, furniture and paper. These trees grow fast and cover huge areas of Europe and North America. These forests are usually managed well so that cut trees are replaced rapidly. This is very different from the hardwoods of the tropical rain forest which we will meet later. |
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Earth Earlier Earlier 300 Million Years ago Later Earth After Plants Later |
Biological Environment > Seed Plants |
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Basic Information |
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