Presentation on theme: "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."— Presentation transcript:
1Chapter 43 OpenerAmorphophallus 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.
3Chapter #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 OpenerAmorphophallus 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.
4Chapter #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.
6Flower PartsFlowers are the reproductive structures of angiosperms, produced by the sporophyte generation.
7Flower 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).
8Flower 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.
9Flowers 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.
10Flower 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.
11Flower PartsPetals – 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).
12Flower PartsCarpel (female reproductive structure) – centrally locatedEach 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.
13Incomplete FlowersFlowers 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.
14Incomplete FlowersIncomplete flowers lack one or more of the four major floral parts:Grass flowers lack both petals and sepalsImperfect flowers are incomplete flowers lacking either stamens (female flowers) or carpels (male flowers).FIGURE 43-9 Wind-pollinated flowersThe 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.
15Incomplete FlowersAmerican 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 flowersPlants 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.
16The 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.
17The Male GametophyteEach 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 grainsThe 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).
18The Male GametophyteEach 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).
19The Male GametophytePollen sacs of anthers split open when male gametophytes are mature.Pollen is dispersed by either animal pollinators or wind currents.
20The Female Gametophyte The embryo sac is the female gametophyte and develops within the ovary of diploid sporophyte plants.Each ovary contains one or more ovulesEach ovule consists of integuments (protective layers of cells) that surround a megaspore mother cellFIGURE 43-9 Wind-pollinated flowersThe 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.
21The 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.
22The Female Gametophyte Plasma membranes partition the cell into a seven-celled embryo sacThree small cells at either end; one is the egg.One large central cell containing two polar nuclei.
23PollinationPollination 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 cellsSperm cells follow pollen tube to the ovule.
24Animal PollinatorsFlowers enhance a plant’s reproductive success because animal pollinators transport pollen from plant to plant as they feed.
25Animal PollinatorsWind 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.
27Double FertilizationDouble 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) zygoteSecond sperm fuses with both polar nuclei to form the endosperm cell.