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
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!
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
Photograph from a Corel CD-ROM
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Header by Viau from Yellowstone
1996,1997, 1998, 1999,
2000, 2002, 2003, 2005.
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