Information on how plants are different from other living things as well as a list of the major groups of plants is presented. Vocabulary algae, kingdom, cellulose, photosynthesis, vascular plant, nonvascular plant Assessment written explanation of importance of plants in your life recognition and identification of different types of plants successfully germinated corn and bean seeds Reading Several hundred million years ago, the land surface of earth was barren. Life existed only in the water. One-celled algae colored the surface waters of the oceans shades of green. Some algae joined together into multicellular organisms and formed what scientists think were the ancestors of modern plants.
Plants are essential to life on earth.
Either directly or indirectly, they are the primary food source for humans and other animals. Whether people eat plants or eat animals that feed on plants, plant life is vital as a food source. Plants play many other essential roles. They are the major producers of oxygen on this planet. All plant life, from the tallest redwood tree to the smallest plankton works to produce oxygen.