Transcript Lesson Overview

Lesson Overview
Reproduction in Flowering Plants
Lesson Overview
24.1 Reproduction in
Flowering Plants
Lesson Overview
Reproduction in Flowering Plants
The Structure of Flowers
• Flowers are reproductive organs composed
of four different kinds of specialized leaves:
sepals, petals, stamens, and carpels.
Lesson Overview
Reproduction in Flowering Plants
Sepals and Petals
• Sepals = outermost circle of floral parts
o Enclose the bud before it opens and
protect the flower while it is developing
• Petals = brightly colored and found just
inside the sepals
o Colors, number, and shapes attract
insects and other pollinators
Lesson Overview
Reproduction in Flowering Plants
Stamens
• Stamens = male parts of the flower
o Consists of a stalk called a filament
with an anther at its tip
o Anthers = structures that produce
pollen grains—the male gametophytes
Lesson Overview
Reproduction in Flowering Plants
Carpels
• Carpels = innermost floral parts—produce
and shelter the female gametophytes and,
later, seeds
oEach carpel has a broad base forming an
ovary, which contains one or more ovules
where female gametophytes are produced
Lesson Overview
Reproduction in Flowering Plants
Carpels
• Pistil = a single carpel or several fused carpels
• Style = diameter of the carpel narrows into a
stalk
• Stigma = the top of the style –a sticky or
feathery portion specialized to capture pollen
Lesson Overview
Reproduction in Flowering Plants
Label the parts of the flower 
Lesson Overview
Reproduction in Flowering Plants
Label the parts of the flower 
Lesson Overview
Reproduction in Flowering Plants
The Angiosperm Life Cycle
• Alternation of generations between diploid
sporophyte phase and haploid gametophyte
stage.
Lesson Overview
Reproduction in Flowering Plants
Development of Male Gametophytes
• The male gametophytes—the pollen
grains—develop inside anthers.
• First, meiosis produces four haploid spore
cells.
Lesson Overview
Reproduction in Flowering Plants
Development of Male Gametophytes
• Each spore undergoes one mitotic division
to produce the two haploid nuclei of a
single pollen grain.
• Two nuclei are surrounded by a thick wall
that protects the male gametophyte.
Lesson Overview
Reproduction in Flowering Plants
Development of Female Gametophytes
• Female gametophytes develop inside each
carpel of a flower.
• The ovules—the future seeds—are enveloped
in a protective ovary—the future fruit.
Lesson Overview
Reproduction in Flowering Plants
Development of Female Gametophytes
• A single diploid cell goes through meiosis
to produce four haploid cells, three of
which disintegrate.
Lesson Overview
Reproduction in Flowering Plants
Pollination
• Pollination = transfer of
pollen to the female
portions of the flower
• Some are wind
pollinated, but most are
by animals
Lesson Overview
Reproduction in Flowering Plants
Pollination
• Insect pollination is beneficial to insects and
other animals because it provides a
dependable source of food—pollen and nectar.
• Plants benefit because the insects take the
pollen directly from flower to flower.
• Insect pollination is more efficient than wind
pollination, giving insect-pollinated plants a
greater chance of reproductive success.
Lesson Overview
Reproduction in Flowering Plants
Fertilization
• If a pollen grain lands on
the stigma of a flower of
the same species, it begins
to grow a pollen tube.
• Of the pollen grain’s two
cells, one cell—the
“generative” cell—divides
and forms two sperm cells.
• The other cell becomes the
pollen tube.
Lesson Overview
Reproduction in Flowering Plants
Fertilization
• The pollen tube
contains a tube nucleus
and the two sperm cells.
• The pollen tube grows
into the style, where it
eventually reaches the
ovary and enters an
ovule.
Lesson Overview
Reproduction in Flowering Plants
Vegetative Reproduction
• Vegetative reproduction is the formation of
new individuals by mitosis and does not
require gametes, flowers, or fertilization
• New plants may grow from roots, leaves,
stems, or plantlets
• This takes place naturally in many plants
Lesson Overview
Reproduction in Flowering Plants
Examples of Vegetative Reproduction
• A potato can grow whole new
plants from buds called “eyes.”
• Strawberry plants send out long,
trailing stems called stolons that
produce roots, stems, and leaves.
• Many cactus species drop
sections of their stems that grow
at the base of the larger adults
Lesson Overview
Reproduction in Flowering Plants
Vegetative Reproduction
• Can reproduce quickly
• Produces genetically identical offspring,
enabling well-adapted individuals to
rapidly fill a favorable environment
• Drawback = no new combinations of
genetic traits
Lesson Overview
Reproduction in Flowering Plants
Plant Propagation (Your plant projects!)
• One of the simplest ways to reproduce
plants vegetatively is by cuttings.
• A grower cuts from the plant a length of
stem that includes a number of buds
containing meristem tissue.
• That stem is then partially buried in soil or
in a special mixture of nutrients that
encourages root formation.