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THE REPRODUCTIVE ROLE OF FLOWERS
Video Summary
This video segment adapted from
NOVA explains how flowers play a
central role in the reproductive cycle of
plants. Their striking array of colors,
patterns, fragrances, and nectar all
require lots of energy to produce. But it
is these features that attract insects and www.teachersdomain.org/resource/oer08.sci.life.stru.flowers
other animals, which, in turn, carry
genetic material from flower to flower. The video describes various parts of the
reproductive system, including the stamens and pistil, which generate seeds and
ensure the survival of an enormous variety of plant species.
Topics Covered:
– Life Science:
Regulation and Behavior
Structure and Function
Evolution and Diversity
Genetics and Heredity
Recommended for Grades 6-12
Media Type: QuickTime Video
Video Length: 3m 59s
Permitted use: Download, Share
This media resource can be used only for non-commercial, educational purposes.
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Discussion Questions
 What is the role of flowers in the plant life cycle?
 What are some characteristics of flowers that draw insects to them and how
do the visits of insects help flowering plants to survive?
 Why are flowers described in this video as the first “advertising”?
 Why do you think that some flowers have developed mechanisms to
prevent self-pollination?
Background Essay
Over millions of years, plants have evolved a variety of adaptations in both form and
function to succeed in their struggle for survival. For the types of plant known as
angiosperms, flowers are an integral part of the plant’s reproductive scheme. Flowers
form on a part of a branch called the receptacle. They consist of several distinct yet
tightly arranged components that emerge from a single node.
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[If you would like to see a diagram of the reproductive components of a flower, refer to
Flower Reproductive Parts GIF Image.]
The sepals and petals are both sterile parts of a flower. The leaf-like sepals surround the
flower, protecting it before it blooms. Petals are colorful and often patterned features that
are more likely to catch one’s eye. Flowers have both male and female reproductive
parts. When these occur in the same structural plan, the flower is described as being
“perfect.” Flowers that contain only male or female parts are called “imperfect.” The
male reproductive parts, called the stamens, produce pollen. Each stamen consists of an
anther, which contains the pollen, and a filament, the stalk-like structure that supports the
anther. The female reproductive parts, or carpels, produce the ovules, or eggs. In most
flowers, the carpels are fused together to form a pistil, which consists of a stigma, an
ovary, and a style—a long tube that connects the stigma to the ovary.
Sexual reproduction in plants occurs when the pollen from a stamen is transferred to a
pistil, where it may fertilize the eggs stored inside the ovary. Plants that grow in isolated
colonies, including tomatoes and lettuces, can pollinate themselves. Pollen simply fertilizes
the eggs on the same flower. However, plants that inhabit a broader area exhibit strategies
that prevent self-pollination. For example, some species produce pollen either before or
after the stigma is receptive to it. These plants conduct an alternate reproductive strategy,
called cross-pollination, through which pollen is carried to a flower of the same species on
a different individual plant, often with an animal assisting in the process.
Insects and other animals do not knowingly participate in plant reproduction. Instead,
they visit flowers for an entirely different reason, typically food. For example, as a
honeybee collects the sweet nectar it seeks from a bright and fragrant flower, it also
unwittingly collects tiny pollen grains, which attach to its legs and body. When it lands on
its next bloom, it leaves behind some of the pollen.
When pollen latches on to the stigma of a receiving flower, a series of chemical reactions
ensues. The pollen produces a pollen tube, which wends its way through the style to
reach the flower’s ovary. The pollen’s sperm cells travel through the pollen tube to
fertilize the eggs. Fertilized eggs develop into seeds, and the ovary develops into a
fruit—the technical term for a structure that encloses and protects a seed or seeds.
Not all flowers are colorful or fragrant. In fact, some flowers lack petals entirely. Instead
of animals, these flowers typically rely on the wind or water for pollination. While these
other methods leave much to chance, the plants benefit from not having to devote so
much energy to producing such “showy” enticements. Instead they generate a larger
volume of pollen to improve their reproductive success rates.
To learn more about the different strategies plants use to ensure pollination, check out
Floral Arrangements.
Reproductive Roll of Flowers
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To learn more about the critical link between honeybee pollination and the produce
humans rely on, check out The Bounty of Bees.
To learn more about the different ways plants transport their seeds to reproduce, check
out Seeds Away.
To learn more about the various stages in the life cycle of a flowering seed plant, check
out Life Cycle of a Seed Plant.
Curricular Standards Correlations:
NSES, Project 2061, MCREL, and state standards correlations available at
www.teachersdomain.org. (Free registration required for your specific state standards correlated to this resource.)
Source: NOVA: “First Flower”
Attribution to be distributed with this media asset: The Reproductive Role of Flowers.
Downloaded from Teachers’ Domain, www.teachersdomain.org
© 2008, 2007 WGBH Educational Foundation. All Rights Reserved.
Original music composed by Tay Chee Wei, Declaffer Music Studios, Singapore.
Collection developed and produced for Teachers’ Domain by:
Collection funded by:
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