Download Examining Parts of a Flower

Unit
Plant Science
Problem Area
Reproduction in Plants
Lesson
Examining Parts of a Flower
Student Learning Objectives
1. Describe the parts of a flower.
 2. Identify the reproductive structures of
plants that exist in the flower.
 3. Describe the difference between
monocot and dicot flowers.
 4. Explain the difference between
pollination and fertilization.
 5. Describe environmental factors that
can influence the beginning of the
flowering process.
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Terms
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Anther
Anthesis
Complete flower
Dicot
Fertilization
Filament
Flower
Imperfect flower
Incomplete flower
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Monocot
Ovaries
Ovule
Perfect flower
Petal
Photoperiodism
Phytochrome
Pistil
Pistillate flower
Terms cont.
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Pollen
Pollination
Sepal
Stamen
Staminate flower
Stigma
Style
Vernalization
What are the major parts of flowers?

A flower is the reproductive part of
flowering plants.
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A. Flowers are in many shapes and colors.
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B. Some flowers are attractive and have
appealing fragrances.
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C. Almost all flowers are important in
producing fruit and seed.
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D. The major parts of flowers are to
support the production of fruit and seed.
 1.
Sepals—The sepals are the green-like
structures beneath the petals. Sepals offer
protection to the developing bud.
 2. Petals—The petals are usually brightly
colored part of the flower and serve to attract
pollinators, such as insect.
 3. Stamens—The male reproductive part of
the flower.
 4. Pistil—The female reproductive part of the
flower.
What reproductive structures exist in the
flower and what are their functions?
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A. The stamen of the male reproductive part of the flower
consists of the anther and filament.
 1. Anther—Produces the pollen or male gamete
(sperm).
 2. Filament—Stalk which supports the anther.
B. The pistil or female reproductive part of the flower
consists of the stigma, style and ovary.
 1. Stigma—Usually has a sticky surface for capturing
pollen.
 2. Style—Tube-like and connects the stigma with the
ovary.
 3. Ovary—Contains the ovules or gametes (eggs).
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C. Plants can be group based on their
reproductive parts.
 1.
Complete flower—A flower that has all four major
parts (sepals, petals, stamens, and pistils).
 2. Incomplete flower—Flowers that lack one or more
of the major parts, such as their petals.
 3. Perfect flower—A flower containing both stamens
and pistils.
 4. Imperfect flower—A flower that lacks either
stamens or pistils.
 5. Pistillate flower—A flower having pistils but no
stamens.
 6. Staminate flower—A flower having stamens but
no pistils.
How is a monocot flower different from a
dicot flower?
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A good way to tell the difference between a
monocot and dicot is to look closely at the
flowers.
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A. Monocots have flowers with flower parts in
multiples of three.
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B. Dicots have flowers with flower parts in
multiples of four or five.
What is the difference between pollination
and fertilization?
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Pollination occurs before fertilization.
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A. Pollination—Occurs when a pollinator, such
as wind, insects, or animals, transfers the pollen
grains from the anther to the stigma. The pollen
grains then germinate and move down the style
until it reaches the ovules in the ovary.
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B. Fertilization—Occurs when the pollen, or
male sex cell, fuses with the egg cell to begin a
new plant.
What environmental factors influence the
formation of flowers?
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A. Photoperiodism—The growth response of a
plant to the length of day or more precisely the
length of light and dark periods.
 1.
Some plants detect the progression of seasons
by reacting to the change of day length.
 2. It is not the length of day but the length of night
that is important to the flowering process.
 3. Long day and short day plants differ in the
photoperiodic conditions required for leaves to
send the signal to flower.
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B. Vernalization—The process by which floral
induction in some plants is promoted by exposing the
plants to cool temperatures for a certain length of time.
 1.
Some plants bloom after a single exposure to the
photoperiod required for flowering; other species
need several successive days of the appropriate
photoperiod.
 2. Still other plants will respond only if they have been
previously exposed to some other environmental
stimulus, such as a period of cold temperatures.
 3. Winter wheat for example will not flower unless it
has been exposed to several weeks of temperatures
below 10°C.
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C. Phytochrome—A pigment occurring in the
cytoplasm of green plants. It is associated with the
absorption of light that affects growth, development,
and differentiation including flowering of a plant,
independent of photosynthesis.
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Phytochrome does not explain the flowering
process in all plants because many species react to
changes in temperature rather than light (ex. winter
wheat).
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D. Anthesis—The release of pollen from the anther,
which may be before the flower opens in selfpollinated crops to several days after the flower has
been open.
Review/Summary
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What are the major parts of flowers?
What reproductive structures exist in the flower
and what are their functions?
How is a monocot flower different from a dicot
flower?
What is the difference between pollination and
fertilization?
Describe environmental factors that can
influence the beginning of the flowering process.