1. Chapter 43 Opener
Amorphophallus titanium, also known as "corpse flower," has rarely been coaxed to bloom in the U.S. The central projection, called a spadix, is often over six feet tall and is filled with small male and female flowers.

2. ? This Week’s Quiz ? This Friday Chapter #43

3. Chapter #43 – Plant Reproduction
What Are the Basic Features of Plant Life Cycles?
How Is Reproduction in Seed Plants Adapted to Drier Environments?
What is the Function and Structure of the Flower?
Chapter 43 Opener
Amorphophallus titanium, also known as "corpse flower," has rarely been coaxed to bloom in the U.S. The central projection, called a spadix, is often over six feet tall and is filled with small male and female flowers.

4. Chapter #43 – Plant Reproduction
43.3 What Is the Function and Structure of the Flower?
Most Flowers Lure Animals that Pollinate Them.
Flowers Are the Reproductive Structures of Angiosperms.
Complete Flowers Have Four Major Parts.
Pollen Contains the Male Gametophyte.
The Female Gametophyte Forms within the Ovule of the Ovary.
Pollination of the Flower Leads to Fertilization.

5. Angiosperm Life Cycle

6. Flower Parts
Flowers are the reproductive structures of angiosperms, produced by the sporophyte generation.

7. Flower Parts Angiosperms bear male and female gametophytes on flowers.
Within each flower, meiosis gives rise to two types of haploid spores.
Megaspore divides by mitosis to form female gametophyte (embryo sac) that is retained within flower.
Microspore divides by mitosis to form male gametophyte (pollen grain).

8. Flower Parts Gametophytes form haploid gametes (n) by mitosis.
Sperm are liberated from pollen grain when it lands on female structure of another plant.
Sperm burrow to egg and fuse to form a diploid zygote that becomes encased in a seed.
Seed germinates to form a new sporophyte.

9. Flowers FIGURE 43-4 The life cycle of a flowering plant
Although this cycle shows the same basic stages as the life cycle of a fern (see Fig. 43-2), the haploid gametophyte stages are microscopic and do not live independently of the diploid plant.

10. Flower Parts Complete flowers have four major parts.
Sepals – located at base of flower; surround and protect the bud.
Dicot sepals are green and leaf-like.
Monocot sepals resemble petals.
FIGURE 43-5b A complete flower
(b) The amaryllis is a complete monocot flower, with 3 sepals (virtually identical to the petals), 3 petals, 6 stamens, and 3 carpels (fused into a single structure). The anthers are well below the stigma, making self-pollination unlikely.

11. Flower Parts
Petals – located above sepals; usually brightly colored and fragrant (attract pollinators).
Stamens (male reproductive structures) – attached above petals.
Each consists of a filament (stalk) and anther (produces pollen).

12. Flower Parts
Carpel (female reproductive structure) – centrally located
Each consists of a sticky stigma (catches pollen), an elongate style, and a bulbous ovary containing one or more ovules.
Ovules develop into seeds.
Ovary develops into a fruit.

13. Incomplete Flowers
Flowers are complete if they have all parts, and perfect if they have both male and female parts.
Grass flowers: incomplete, usually imperfect (separate male and female flowers)
A tulip is complete (though the sepals are the same color as the petals) and perfect.

14. Incomplete Flowers
Incomplete flowers lack one or more of the four major floral parts:
Grass flowers lack both petals and sepals
Imperfect flowers are incomplete flowers lacking either stamens (female flowers) or carpels (male flowers).
FIGURE 43-9 Wind-pollinated flowers
The flowers of grasses and many deciduous trees are wind pollinated, with anthers (yellow structures hanging beneath the flowers) exposed to the wind. Petals are reduced or absent.

15. Incomplete Flowers
American holly bears separate male and female flowers on separate plants; fruits develop on female plants.
Zucchini bears separate male and female flowers on the same plant; fruits develop from female flowers.
FIGURE 43-6 Male and female flowers
Plants of the squash family, such as these zucchinis, bear separate female (left) and male (right) flowers. Each plant initially produces only male flowers, ensuring some cross-pollination between plants that flower at slightly different times. Note the small zucchini (actually a fruit) forming at the base of the female flower. Zucchini fruits are produced only by female flowers.

16. The Male Gametophyte Pollen contains the male gametophyte.
Pollen develops within anthers of diploid sporophyte plants.
Pollen grains have tough protective coats that exhibit species-specific shapes and patterns.

17. The Male Gametophyte
Each anther consists of four pollen sacs that contain microspore mother cells.
Each diploid microspore mother cell divides by meiosis to form four haploid microspores.
FIGURE 43-8 Pollen grains
The tough outer coats of many pollen grains are elaborately sculptured in species-specific shapes and patterns. The pollen grains in this false-color SEM photo are from a geranium (orange), a tiger lily (fuschia), and a dandelion (yellow).

18. The Male Gametophyte
Each microspore divides by mitosis to form an immature male gametophyte consisting of two cells.
Tube cell (will form a pollen tube after pollination).
Generative cell (will divide by mitosis to form two sperm after pollination).

19. The Male Gametophyte
Pollen sacs of anthers split open when male gametophytes are mature.
Pollen is dispersed by either animal pollinators or wind currents.

20. The Female Gametophyte
The embryo sac is the female gametophyte and develops within the ovary of diploid sporophyte plants.
Each ovary contains one or more ovules
Each ovule consists of integuments (protective layers of cells) that surround a megaspore mother cell
FIGURE 43-9 Wind-pollinated flowers
The flowers of grasses and many deciduous trees are wind pollinated, with anthers (yellow structures hanging beneath the flowers) exposed to the wind. Petals are reduced or absent.

21. The Female Gametophyte
Megaspore mother cell divides by meiosis to form four haploid megaspores (three degenerate, one survives).
Nucleus of remaining megaspore divides by mitosis three times (without cytokinesis) to form a single cell with 8 haploid nuclei.

22. The Female Gametophyte
Plasma membranes partition the cell into a seven-celled embryo sac
Three small cells at either end; one is the egg.
One large central cell containing two polar nuclei.

23. Pollination
Pollination occurs when a pollen grain lands on the stigma of a compatible plant.
Pollen grain absorbs water and germinates.
Tube cell extends, forming a pollen tube that grows down the style.
Generative cell divides (mitosis) to form two sperm cells
Sperm cells follow pollen tube to the ovule.

24. Animal Pollinators
Flowers enhance a plant’s reproductive success because animal pollinators transport pollen from plant to plant as they feed.

25. Animal Pollinators
Wind pollination is inefficient because most pollen grains fail to reach their target.
Flowering plants (angiosperms) evolved from gymnosperms.
Flowers produce pollen and nectar that attract animal pollinators (bees, moths, butterflies, hummingbirds).

26. ? Check Your Thinking ? Concept check:
Some students confuse pollination with fruit dispersal. Understand and be able to explain the difference.
Some students confuse seed germination with plant growth. Understand and be able to explain the difference.

27. Double Fertilization
Double fertilization is unique to flowering plants.
Double fertilization is the process by which two sperm fuse with two cells of the embryo sac.
One sperm fuses with the egg to form the diploid (2n) zygote
Second sperm fuses with both polar nuclei to form the endosperm cell.