Angiosperm Reproduction Chapter 38
Phylum Bryophyta Moss Non vascular Gametophyte is dominant generation (1n)
Vascular plants Phylum Pterophyta: Ferns Sperm flagellated (swim) Water required for fertilization
Phylum Anthophyta Angiosperms Most advanced vascular plants Flowering Phylum Coniferophyta Gymnosperms
Angiosperm plant reproduction Adult plant is a sporophyte Diploid Flowering Gametophyte Haploid
Organs 1. Sepal 2. Petal Reproductive organs 3. Stamens Flowers - Filament - Anther w/ pollen sacs (microsporangia) 4. Carpals (pistil) Stamen - Ovary - Style + Stigma (sticky to receive pollen) Anther Filament Petal Receptacle Stigma Style Ovary Sepal (a) Structure of an idealized flower Carpel
elderberry Great diversity in flower types Flower types Complete flowers have the 4 floral organs (both male and female)
Incomplete flowers May lack petals, sepals, repro organs Knotweed lacks petals Squash flower
Male gametophyte = pollen grain (microscopic) Completes its development in anther
Pollen sac (microsporangia) contain microsporocyte cells (2n) which divide into 4 microspores (1n)
Each microspore contains: 1 generative cell produces 2 sperm cells 1 tube cell will produce pollen tube
Pollen is unique
(a) Development of a male gametophyte (in pollen grain) Microsporangium (pollen sac) animation Microsporocyte (2n) MEIOSIS 4 microspores (n) Each of 4 microspores (n) Generative cell (n) forms 2 sperm Male gametophyte MITOSIS 75 µm 20 µm Nucleus of tube cell (n) Ragweed pollen grain
Female Gametophyte = embryo sac Location: Ovary Megasporocytes(2n) Produce 4 megaspores cells (1n) in ovules 1 megaspore survives female gametophyte
100 µm (b) Development of a female gametophyte (embryo sac) MEIOSIS Ovule Megasporangium (2n) Megasporocyte (2n) Integuments (2n) Micropyle Surviving megaspore (n) MITOSIS Ovule Integuments (2n) 3 antipodal cells (n) 2 polar nuclei (n) 1 egg (n) 2 synergids (n) Female gametophyte (embryo sac) Embryo sac
Female gametophyte contains: 1 Ovum 2 Polar nuclei
Pollination
Wind 20% of angiosperms Inconspicuous flowers Abiotic Pollination by Wind Ex. grasses No advantage to colorful flowers Hazel staminate flowers (stamens only) Hazel carpellate flower (carpels only)
Pollination by Bees Insects 65% of angiosperms Nectar Flowers bright colors Bees most important Common dandelion under normal light Common dandelion under ultraviolet light
Pollination by Moths and Butterflies Anther Stigma Moth on yucca flower
Pollination by Birds Hummingbird drinking nectar of poro flower Birds
Pollination by Bats Long-nosed bat feeding on cactus flower at night
Fertilization 1. Pollen grain lands on stigma Absorbs water Tube cell produces pollen tube
2 sperm released to female gametophyte Ovule Polar nuclei Egg Synergid 2 sperm
Double fertilization 2 sperm released to female gametophyte - Attracted to egg by chemicals - 1 sperm fertilizes egg to form zygote (2n) - Other sperm unites with polar nuclei to form 3n endosperm
Endosperm nucleus (3n) (2 polar nuclei plus sperm) Zygote (2n) (egg plus sperm)
Lily plant
Anther Pollen tube Germinated pollen grain (n) (male gametophyte) Ovary Ovule Embryo sac (n) (female gametophyte) FERTILIZATION Egg (n) Sperm (n) Key Mature sporophyte plant (2n) Zygote (2n) Haploid (n) Diploid (2n) Germinating seed Seed Seed Embryo (2n) (sporophyte) (b) Simplified angiosperm life cycle Simple fruit
True or false? 1. Plants are the only photosynthetic organisms on Earth 2. Plants are heterotrophic organisms 3. Plants reproduce by binary fission 4. Angiosperms use double fertilization in sexual reproduction 5. Fern plants do not produce pollen 6. All stems are above ground 7. Apical buds are also lateral buds 8. Xylem is a vascular tissue of plants 9. Dermal tissue may be covered by a cuticle 10. Adult sporophytes may contain embryonic, meristematic, tissue 11. The male gametophyte is a pollen grain 12. Soil bacteria fix atmospheric nitrogen 13. A complete flower has both anther and carpal 14. Microsporocyte cells are located in the plant ovary 15. Angiosperms contain the embryo in a seed 16. Haploid refers to a cell with 2 sets of chromosomes 17. Fertilization is the same process as pollination
Seed Development (Chapter 38) Each ovule develops into a seed Ovary becomes the fruit enclosing the seeds
Seed coat - hard protection around embryo Seed is dehydrated Tomato seeds with seed coat Apple seeds with seed coat
In the seed: Endosperm - Forms from 1 sperm + 2 polar nuclei (3n, triploid) Contains nutrients 3n 2n
Seeds with endosperm Coconut has liquid and solid endosperm
Mitosis cell division Plant development Zygote embryo seedling plant
The mature seed Dehydrated Dormant Metabolism/growth ceases Hard, protective seed coat Cotyledon Becomes first leaves (monocot and eudicot) Radicle Embryonic root radish
Seed develops from ovule Seed coat Radicle Epicotyl Hypocotyl Cotyledons (a) Common garden bean, a eudicot with thick cotyledons
seed coat, embryo, cotyledons, endosperm Bean germination
Radicle, cotyledon, seed coat Foliage leaves Cotyledon Hypocotyl Cotyledon Hypocotyl Epicotyl Cotyledon Hypocotyl Radicle Seed coat (a) Common garden bean Dicot
Foliage leaves Coleoptile Coleoptile Radicle (b) Maize monocot
Germination when conditions for growth are favorable Examples: Desert plant seeds germinate after substantial rainfall
Some seeds require exposure to winter/cold Some must pass through animal digestive tract to soften seed coat Some require fire Buttercup seed requires exposure to cold
Fruit forms from ovary Fruit protects seeds Aids in seed dispersal Dry fruits Nuts, legumes Columbine Milkweed Sweet pea Beans Peanut Runner Bean buckwheat sunflower Wheat Rice Corn Barley Rye Oats Walnut Hazelnut Chestnut Acorn
Fleshy fruits Lemon Grapefruit Limes Citron Mandarin Clementine Ugli fruit Orange Grapes Tomatoes Bananas Avocados Raspberry Eggplants Currants Persimmons Pears Apples Quince Chokeberry Haw Juneberry Medlar Rowan Sorb apple Cherry Peach Plum Apricot Olive Lychee Pin cherry Coconut Cucumber Watermelon Squash Pumpkin Honeydew melon Sunberry Blackberry Raspberry Boysenberry Loganberry Cloudberry Wineberry Strawberry Mulberry Pineapple Fig Pomegranate Date Cornelian cherry Goumi Jujube Jackfruit Loquat Kumquat Persimmon Kiwi Guava Longan Lychee Akee Breadfruit Camu Camu Carambola Chempedak Custard apple Durian Guarana Mamoncillo Mango Papaya Pineapple Rose apple Tamarind
Seed dispersal mechanisms include: 1. Water Dispersal by Water Ex. coconut is buoyant Coconut
2. Wind dispersal parachute Whirling Nut (Gyrocarpus) sycamore
3. animal dispersal Burdock seeds Tomato seeds
Stamen Ovary Fruits classified by developmental features: Simple Fruit Develops from one ovary Pea flower Stigma Ovule Seed (a) Simple fruit Pea fruit
Tomato Fruit: The solitary Ovary has produced one Fruit.
Aggregate fruit One flower, many ovaries (carpals fuse) Ex. strawberry
Multiple fruit