Chapter 12
Introduction to Plants
Section 1: Objectives
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Identify 4 characteristics that all plants share.
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Describe the 4 main groups of plants.
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Explain the origin of plants.
Plant Characteristics
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One plant may seem different than another,
but all plants have certain things in common.
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Plants come in a variety of shapes and sizes.
All plants have the following in common:
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Photosynthesis
Cuticles
Cell walls
Plant Characteristics
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All plant cells contain chlorophyll (green
pigment).
Chlorophyll is found in chloroplasts.
Plants use energy from sunlight to make food
from carbon dioxide and water.
This process is called photosynthesis.
This makes all plants producers.
Plant Characteristics
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Most plants live on dry land and need
sunlight to survive.
But why don’t plants dry out?
Plants are protected by a cuticle.
A cuticle is a waxy layer that coats the
surfaces of plants.
This keeps the plant from drying out.
Plant Characteristics
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How do plants stay upright?
They have no skeleton or muscles for
support.
They have a rigid cell wall instead.
Carbohydrates and proteins form a hard
material inside the cell wall.
Cell walls support and protect the plant cell.
Plant Cell Diagram
Plant Characteristics
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Plants have 2 stages in their life cycle:
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Sporophyte stage: plants make spores
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In suitable environments, the spores of these plants
grow into new plants.
Gametophyte stage: plant produces sex cells
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These cells cannot grow into new plants.
Instead the cells grow into spores and the cycle repeats.
Plant Characteristics
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Plants can be divided into 2 main groups:
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Nonvascular plants: lack roots, stems, and leaves
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Example: mosses
Vascular plants: has roots, stems, or leaves
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Example: Tomato plants
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These are the 2 main groups that make up Kingdom
Plantae.
Plant Characteristics
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Vascular plants are divided into 3 groups:
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Seedless plants
Gymnosperms
Angiosperms
Non-flowering seedless plants are called
gymnosperms.
Flowering seedless plants are called
angiosperms.
Plant Groups Chart
Plant Characteristics
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What other organisms do plants share a
common ancestor with?
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What is a common ancestor?
Because plants and algae share many
similarities, scientists believe that they share
a common ancestor.
Section 2: Objectives

List 3 nonvascular plants and 3 seedless
vascular plants.
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Explain how seedless plants are important to
the environment.
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Describe the relationship between seedless
vascular plants and coal.
Nonvascular Plants
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These types of plants don’t have vascular tissue.
They grow in places that are damp and moist.
Each cell of the plant must get water from the
environment.
Remember, these plants don’t have roots, stems,
or leaves.
Examples: mosses, liverworts, & hornworts
Nonvascular Plants
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Reasons these plants are important to the
environment:
– First to grow in a new environment
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Reduce soil erosion
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Food source for some animals
Mosses
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Mosses often live together in large groups.
They cover soil or rocks with a mat of tiny
green plants.
Mosses have leafy stalks and rhizoids.
A rhizoid is a root-like structure that holds
the plants in place and helps plants get water
and nutrients.
Liverworts and Hornworts
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Like mosses, liverworts and hornworts are
usually small, nonvascular plants that usually
live in damp places.
Nonvascular plants are usually the first
plants to live in a new environment, such as
newly exposed rock.
When these nonvascular plants die, they
form a thin layer of soil.
Seedless Vascular Plants
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Examples include ferns, horsetails, and club
mosses.
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These plants once grew much taller than they
actually do today.
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In order to adapt to their environments, these
plants change their shape and height over time.
Ferns
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These grow in many places ranging from
cold to warm climates.
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Most ferns have a rhizome- an underground
stem from which leaves and roots grow.
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Ferns still go through the sporophyte and
gametophyte stages in their life cycle.
Sporophyte vs. Gametophyte
Importance of Seedless Vascular Plants
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These play many roles in the environment:
– Help form soil
– Prevent soil erosion
– Popular houseplants
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The remains of ancient ferns and club
mosses form coal.
Coal is a fossil fuel and is used for energy.
Section 3: Objectives
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Describe 3 ways that seed plants differ from
seedless plants.
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Describe the structure of seeds.
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Compare angiosperms and gymnosperms.
Characteristics of Seed Plants
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As with seedless plants, the life cycle of seed
plants alternates between 2 cycles:
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Sporophyte stage: plant produces spores
to be distributed
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Gametophyte stage: plant produces sex
cells which mature into spores
Characteristics of Seed Plants
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Seed plants produce seeds.
Unlike other plants, these plants produce tiny
structures called seeds which help nourish
and protect the sporophyte.
Pollen forms within these plants.
Pollen: tiny granules that contain the male
gametophyte of seed plants.
Structure of Seeds
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A seed forms after fertilization in plants.
Seeds have some advantages over seedless
plants:
– Have their own food supply
– Seeds can be spread by animals
– Animals spread seeds more efficiently than
wind spreads spores.
Structure of Seeds
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A seed is made up of 3 parts:
– Young plant (sporophyte)
– Stored food
– Seed coat
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The purpose of the seed coat is to
surround and protect the sporophyte.
Parts of A Seed
Gymnosperms
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These are seed plants that do not have flowers
or fruits.
These seeds are usually protected by a cone.
Any plant/tree that has cones would be an
example of a gymnosperm.
Pine trees are probably the most popular
example.
Gymnosperms
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Conifers are probably the most familiar
example.
The word conifer comes from 2 words:
“cone-bearing.”
Pollination: the transfer of pollen from the
male reproductive structure to the female
reproductive structure of seed plants
Gymnosperm Life Cycle
Angiosperms
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Vascular plants that produce flowers and fruits.
Most abundant group of plants.
Can be found in almost every ecosystem.
Flowers help angiosperms reproduce and some
depend on wind to transfer pollen from plant to
plant.
Angiosperms
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Divided into 2 classes:
– Monocots: have one seed coat
 Grasses, onions, palm trees
 Tips of flowers separate in parts of 3
 Leaves have parallel veins
– Dicots: have 2 seed coats
 Roses, cactuses, sunflowers
 Tips of flowers are separated in parts of 4 or 5
 Leaves have branching veins
Monocots and Dicots
Angiosperms
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Flowering plants provide many land animals
with the food they need to survive.
People use flowering plants in many ways.
• Major food crops, such as corn, wheat,
and rice, are flowering plants.
Flowering plants are used to make cloth
fibers, rope, medicines, rubber, perfume oil,
and building materials.
Chapter 12 Sec. 3 Pop Quiz
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1)List 2 characteristics of seed plants.
2) When does a seed form in plants?
3) List the 3 parts of seeds.
4) What is the difference between
gymnosperms and angiosperms?
5) What does “conifer” mean?
6) List and describe the 2 groups of
angiosperms.
Section 4: Objectives
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List three functions of roots and three
functions of stems.
Describe the structure of a leaf.
Identify the parts of a flower and their
functions.
Transportation In Plants
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There are two types of vascular tissue in plants:
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Xylem is the type of tissue in vascular plants that
provides support and conducts water and
nutrients from the roots.
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Phloem is the tissue that conducts food in
vascular plants.
Transportation In Plants
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Root Functions: The following are the main
functions of roots:
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Roots supply plants with water and dissolved
minerals.
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Roots hold plants securely in the soil.
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Roots store surplus food made during
photosynthesis
Transportation In Plants
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The layers of cells that cover the surface of the roots
is called the epidermis.
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After water and minerals are absorbed by the
epidermis, they diffuse into the center of the root
where the vascular tissue is located.
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A root cap can be found at the end of the root.
• The root cap protects the tip and helps the root
continue to grow.
Transportation In Plants
Transportation In Plants
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There are two kinds of root systems— taproot
systems and fibrous root systems.
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Taproot systems have a main root, or tap root, that
grows downward. Dicots and gymnosperms usually
have tap root systems.
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Fibrous systems have several roots that spread out
from the base of the stem. Monocots usually have
fibrous root systems.
Transportation In Plants
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A stem connects a plant’s roots to its leaves and
flowers. A stem also has the following functions:
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Stems support the plant body.
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Stems transport materials between the root
system and the shoot system.
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Some stems store materials.
Transportation In Plants
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Many plants have stems that are soft, thin,
and flexible.
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These stems are called herbaceous stems.
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A cross section of an herbaceous stem is
shown on the next slide.
Herbaceous Plant Stems
Transportation In Plants
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Trees and shrubs have rigid stems made of
wood and bark.
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This wood and bark provides for more
support.
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These stems are called woody stems.
Woody Plant Stems
Transportation In Plants
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The main function of leaves is to make food
for the plant.
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The structure of leaves, shown on the next
slide, is related to their main function—
photosynthesis.
Leaf Structure Diagram
Transportation In Plants
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Some leaves have functions other than
photosynthesis.
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The leaves of many cactuses are modified as
spines. These spines keep animals from eating
the cactuses.
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The leaves of sundews are modified to catch
insects, which the sundew digests.
Transportation In Plants
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Flowers are adaptations for sexual
reproduction.
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Sepals and Petals The modified leaves
that make up the outermost ring of flower
parts and protect the bud are called sepals.
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Petals are broad, flat, thin leaflike parts of a
flower.
Transportation In Plants
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The male reproductive structure of a flower is
called a stamen.
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A pistil is the female reproductive structure
of a flower.
Plant Structure Diagram