Plants
Plants
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The plant world is a diverse world.
There are plants that trap animals, others
that bloom every 30 years, and still others
that smell like rotting meat!!!
Although you probably don’t see these
uncommon plants everyday, all plants, the
common and the bizarre, all share some
common traits.
What is a Plant?
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Members of the plant kingdom share many
characteristics.
All plants are autotrophs, or organisms
that produce their own food. All plants
are eukaryotes that contain many cells.
In addition, all plant cells are
surrounded by a cell wall.
Adaptations for living on
Land
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Most plants live on the land. How is this any
different from living in the water?
Think about this…
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Multicellular green algae float around in the ocean.
They obtain water and other materials DIRECTLY
from the water around them.
For plants to survive on land, they must have
ways to obtain water and other nutrients
from their surroundings, retain water,
transport materials in their bodies, support
their bodies, and reproduce.
Obtaining Water
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All organisms need water to survive
(DUH!)
Obtaining water is easy for something like
algae, it just diffuses into the cell. Its
trickier for plants though…
Because most plants live on land, they
need adaptations for obtaining water from
the soil. Plants also must have ways to
obtain nutrients from the soil.
Retaining Water
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After getting water, plants need a means of
holding onto it. If they weren’t able to, they
could easily dry out due to evaporation.
When there is more water in plant cells than the
air around it, water leaves the plant and enters
the air.
One adaptation that helps the plant reduce
water loss is the cuticle.
Cuticle: Waxy, waterproof layer that covers the
leaves of most plants.
Transporting Materials
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A plant needs to be able to transport food,
water, minerals, and other materials from
one part of its body to another.
In general, water and minerals are taken
up by the bottom part of the plant while
food is made at the top. Even though this
is the case ALL plant cells need water,
food, and minerals.
Transporting Materials (cont.)
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In tiny plants, materials simply move from
one cell to the next.
Larger plants need a better method of
transport, so these plants have a tissue
that transports material called vascular
tissue.
Vascular Tissue: A system of tube-like
structures inside a plant through which
water, minerals, and food move.
Transporting Materials (cont.)
Xylem: Vascular tissue that helps
transport water and nutrients up a
vascular plant.
 Phloem: Vascular tissue that helps
transport food down a vascular plant.
 Cambium: Produces new xylem and
phloem.
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Support
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A plant must be able to support its own
body. Again, this is a simple task for small
plants as they have less body to hold up,
but can be difficult for larger plants.
Large plants’ food making parts need to
be exposed to as much sunlight as
possible, so they have a series of rigid cell
walls and vascular tissue to strengthen
and support their bodies.
Reproduction
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All plants undergo sexual reproduction that
involves fertilization.
For algae and some plants, this can only
happen in a water environment. This is
because the sperm cells swim through the
water to reach the egg cells.
Other plants have adapted in a way that
they can reproduce sexually on land.
Reproduction
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Many plants have developed a specific
adaptation to allow them to reproduce sexually
on land.
Pollen: Carries plant sperm cells that allow for
sexual reproduction on land.
Plants that pollinate create seeds as a result.
Seed: A structure that contains a small plant
inside.
Seeds!
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As stated previously, seeds contain immature
developing plants. Since plants make food
through photosynthesis, and plants in seeds
don’t receive sunlight, they need some food
stored so that they can bust out of their shells.
Cotyledon: Leaves in seeds that store food for a
developing plant.
Germination: When a juvenile plant breaks out
of a seed.
Classifying Plants
Hundreds of thousands of plant
species exist in the world today.
 Scientists informally group
plants into two major groups:
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 Nonvascular
plants
 Vascular plants
Nonvascular Plants
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Nonvascular Plants: Plants that lack a system
of tubes for transporting water and other
materials.
Characteristics of nonvascular plants:
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Low growing
No roots
Obtain water and materials directly from their
surroundings
Because they get things directly from their
environments, they usually live in damp, shady
places.
Vascular Plants
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Vascular Plants: Plants with true vascular
tissue.
Characteristics of vascular plants:
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Better suited to live in dry areas
Can grow tall due to extra support of vascular
system
More efficient at moving materials through their
bodies
Often obtain nutrients and water from soil with
roots
Vascular Plants
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Unlike non-vascular plants, vascular plants
have roots to allow them to absorb water
and nutrients from the soil, as well as
anchor them in place. Roots need to
burrow deep into the ground, so they have
special tissue to protect them as they do.
Root cap: Protective layer around the
roots of vascular plants.
Complex Life Cycles
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Plants have complex life cycles that include
two different stages, the sporophyte stage
and the gametophyte stage.
Sporophyte Stage: Stage where plants
produce tiny spores that grow into a new
organism.
Spore: Tiny cell that can grow into a new
organism.
Gametophyte Stage: Stage where the plant
produces sperm and egg cells.