World Builders™
World Builders™
Session Eight --  Land Plants
Session Eight  --  Land Plants

Plants on Land
Plants on Land

Home Page for Unit Eight
Home Page for Unit Eight

When the algae moved onto the land, they developed into plants and diversified.

     Living on land presents many problems for plants. They are no longer supported by water, so they must grow strong stems. They can get dried out if it doesn't rain. There are wider, and more rapid, fluctuations in temperature. Land plants have to find new ways to reproduce, and they have to deal with wind. However, there is more sunlight available, and capturing energy is what plants do. How can they adapt to compete with other plants for light?

    On earth, plants proved to be innovative and adaptable. They developed true roots that absorbed water and minerals and anchored them firmly to the ground. They developed vascular structures that distributed water and nutrients to every living cell. They developed energy storage structures such as tubers, bulbs, and the cotyledons of seeds. They developed reproductive structures that included spores and seeds, and eventually led to in the development of the flower. They also developed leaves that could "breathe", taking in carbon dioxide from the air and releasing oxygen through their stomata.  Plants used these innovations to develop an astonishing variety of leaf shapes, flower designs and adaptations to challenging special conditions.

     Go back to your climate maps from Week 3 and see what sorts of conditions your plants will have to deal with. Do you have extreme seasonal changes? Do you have deserts as well as wet places? How will the plants make the transition from sea to shore? The first plants will probably be small and tough. What will they evolve into? Think about the processes of growth for the individual and evolution for the species. You could show these processes with animated gifs!


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Assignment:

Do This In Class:
  • decide how your plants get out onto the land. How do they cope with dehydration? How do they support themselves physically? How do they reproduce?
  • write a description of these processes
  • decide which plants grow in which climatic zones
  • sketch out the plant forms with evolutionary stages
  • diagram the plant evolution
  • sketch the plants and write descriptions of them
  • each student will design one basic land plant and then "evolve it" so that it can live in two other biomes

Homework: Bring to class next session:

  • Your web-ready page with graphics that shows your plants adapted for three biomes
  • Your diagram of plant evolution.
  • Your drawings of the stages of evolution of the plants.
  • The written description of different kinds of plants (with sketches) in the different climatic zones

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