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Internet Sources for Reproductive Biology of Flowering Plants

Internet Sources for Reproductive Biology of Flowering Plants. http://www.mnstate.edu/stockram/30C2-Angiosperms.ppt#276,1,Slide 1 http://koning.ecsu.ctstateu.edu/Plants_Human/lecppt/flower.ppt http://www.ecfs.org/projects/pchurch/Campbell%207th%20Powerpoints/38%20ANGIOSPERMS.ppt

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Internet Sources for Reproductive Biology of Flowering Plants

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  1. Internet Sources for Reproductive Biology of Flowering Plants • http://www.mnstate.edu/stockram/30C2-Angiosperms.ppt#276,1,Slide 1 • http://koning.ecsu.ctstateu.edu/Plants_Human/lecppt/flower.ppt • http://www.ecfs.org/projects/pchurch/Campbell%207th%20Powerpoints/38%20ANGIOSPERMS.ppt • http://csmweb.csm.edu/cfp/faculty/coswald/notes/CPB730_TXT.ppt#260,1,Chapter 30 • http://www-instruct.nmu.edu/biology/DBecker/BI%20230/Angiosperms.ppt • http://faculty.fmcc.suny.edu/freeman/webpages/plant/powerpoint/angiosperms.ppt

  2. Magnoliophyta

  3. Fossil Angiosperms Primitive fossils of 125-million-year-old angiosperms Display both derived and primitive traits Carpel Stamen 5 cm (a) (b) Archaefructus sinensis, a 125-million-year- old fossil. Artist’s reconstruction of Archaefructus sinensis

  4. Angiosperm Evolution Clarifying the origin and diversification of angiosperms Poses fascinating challenges to evolutionary biologists Angiosperms originated at least 140 million years ago And during the late Mesozoic, the major branches of the clade diverged from their common ancestor

  5. Angiosperm Diversity The two main groups of angiosperms Are monocots and dicots Basal angiosperms Are less derived and include the flowering plants belonging to the oldest lineages Magnoliids Share some traits with basal angiosperms but are more closely related to monocots and eudicots

  6. Exploring Angiosperm Diversity BASAL ANGIOSPERMS Amborella trichopoda Star anise (Illicium floridanum) Water lily (Nymphaea “Rene Gerard”) HYPOTHETICAL TREE OF FLOWERING PLANTS Star anise and relatives Monocots Eudicots Water lilies Amborella Magnoliids MAGNOLIIDS Southern magnolia (Magnolia grandiflora)

  7. Magnolia virginiana flower Kindom Plantae Division Magnoliophyta Class Magnoliopsida - DicotsClass Liliopsida - Monocots Source: http://en.wikipedia.org/wiki/Magnoliophyta

  8. Class Magnoliposida The dicotyledons

  9. Class Liliopsida The monocotyledons

  10. Characteristics of Angiosperms The key adaptations in the evolution of angiosperms Are flowers and fruits

  11. Flowers The flower Is an angiosperm structure specialized for sexual reproduction

  12. A flower is a specialized shoot with modified leaves Sepals, which enclose the flower Petals, which are brightly colored and attract pollinators Stamens, which produce pollen Carpels, which produce ovules Carpel Stigma Anther Style Stamen Ovary Filament Petal Sepal Receptacle Ovule

  13. stigma style ovary The carpel ovule megasporocyte micropyle

  14. Creation of the megaspore

  15. megaspore Creation of the megaspore

  16. Creation of the female gametophyte

  17. antipodals Polar nuclei synergids Egg nucleus Creation of the female gametophyte

  18. antipodals Polar nuclei synergids Egg cell Mature female gametophyte = embryo sac

  19. Review: meiosis Megasporocyte (2N) Megaspore (N) Mitosis and rearrangement Female gametophyte (N) Megaspore (N) Female gametophyte contains the egg cell

  20. anther filament Stamen

  21. Pollen sac microsporocyte Cross section of an anther

  22. microspore microsporocyte Creation of microspores

  23. Review: meiosis microspore microsporocyte Creation of microspores Next step: creation of male gametophyte

  24. exine

  25. Generative cell Tube cell nucleus Pollen grain

  26. pollination

  27. Generative nucleus Tube nucleus Pollen germination

  28. sperm Tube nucleus

  29. sperm Tube nucleus Mature Male gametophyte

  30. Review: meiosis microsporocyte (2N) microspore (N) Mitosis and rearrangement Male gametophyte (N) microspore (N) Male gametophyte contains the sperm

  31. sperm Tube nucleus antipodals Polar nuclei synergids Egg cell

  32. sperm Tube nucleus antipodals Polar nuclei synergids Egg cell

  33. Primary endosperm nucleus 3N 2N Zygote Polar nuclei Egg cell Double Fertilization

  34. Seed coat endosperm embryo fruit

  35. The Angiosperm Life Cycle In the angiosperm life cycle Double fertilization occurs when a pollen tube discharges two sperm into the female gametophyte within an ovule One sperm fertilizes the egg, while the other combines with two nuclei in the center cell of the female gametophyte and initiates development of food-storing endosperm The endosperm Nourishes the developing embryo

  36. The reduced gametophytes of seed plants are protected in ovules and pollen grains In addition to seeds, the following are common to all seed plants Reduced gametophytes Heterospory Ovules Pollen

  37. The life cycle of an angiosperm Key 1 Anthers contain microsporangia. Each microsporangium contains micro- sporocytes (microspore mother cells) that divide by meiosis, producing microspores. 2 Microspores form pollen grains (containing male gametophytes). The generative cell will divide to form two sperm. The tube cell will produce the pollen tube. Haploid (n) Diploid (2n) Microsporangium Anther Microsporocytes (2n) Mature flower on sporophyte plant (2n) MEIOSIS Microspore (n) Generative cell 7 When a seed germinates, the embryo develops into a mature sporophyte. Ovule with megasporangium (2n) Tube cell Male gametophyte (in pollen grain) Ovary Pollen grains MEIOSIS Germinating Seed Stigma In the megasporangium of each ovule, the megasporocyte divides by meiosis and produces four megaspores. The surviving megaspore in each ovule forms a female gametophyte (embryo sac). 3 Pollen tube Megasporangium (n) Embryo (2n) Sperm Endosperm (food Supply) (3n) 6 The zygote develops into an embryo that is packaged along with food into a seed. (The fruit tissues surround- ing the seed are not shown). Surviving megaspore (n) Seed Pollen tube Seed coat (2n) Style Antipodal cells Polar nuclei Synergids Egg (n) Female gametophyte (embryo sac) Pollen tube Zygote (2n) Nucleus of developing endosperm (3n) Egg Nucleus (n) Sperm (n) After pollina- tion, eventually two sperm nuclei are discharged in each ovule. 4 FERTILIZATION Double fertilization occurs. One sperm fertilizes the egg, forming a zygote. The other sperm combines with the two polar nuclei to form the nucleus of the endosperm, which is triploid in this example. 5 Discharged sperm nuclei (n)

  38. The Evolutionary Advantage of Seeds A seed Develops from the whole ovule Is a sporophyte embryo, along with its food supply, packaged in a protective coatThe reduced gametophytes of seed plants are protected in ovules and pollen grains In addition to seeds, the following are common to all seed plants Reduced gametophytes Heterospory Ovules Pollen

  39. Seeds changed the course of plant evolution Enabling their bearers to become the dominant producers in most terrestrial ecosystems

  40. Fruits Fruits Typically consist of a mature ovary (b) Ruby grapefruit, a fleshy fruitwith a hard outer layer andsoft inner layer of pericarp (a) Tomato, a fleshy fruit withsoft outer and inner layersof pericarp (c) Nectarine, a fleshyfruit with a soft outerlayer and hard innerlayer (pit) of pericarp (d) Milkweed, a dry fruit thatsplits open at maturity (e) Walnut, a dry fruit that remains closed at maturity

  41. KEY TO FRUIT TYPES • http://www.unm.edu/~jerusha/fruit_types.htm

  42. Can be carried by wind, water, or animals to new locations, enhancing seed dispersal (a) Wings enable maple fruits to be easily carried by the wind. (b) Seeds within berries and other edible fruits are often dispersed in animal feces. (c) The barbs of cockleburs facilitate seed dispersal by allowing the fruits to “hitchhike” on animals.

  43. Evolutionary Links Between Angiosperms and Animals Pollination of flowers by animals and transport of seeds by animals Are two important relationships in terrestrial ecosystems (c) A flower pollinated by nocturnal animals. Some angiosperms, such as this cactus, depend mainly on nocturnal pollinators, including bats. Common adaptations of such plants include large, light-colored, highly fragrant flowers that nighttime pollinators can locate. (a) A flower pollinated by honeybees. This honeybee is harvesting pollen and nectar (a sugary solution secreted by flower glands) from a Scottish broom flower. The flower has a tripping mechanism that arches the stamens over the beeand dusts it with pollen, some ofwhich will rub off onto the stigmaof the next flower the bee visits. (b) A flower pollinated by hummingbirds.The long, thin beak and tongue of this rufous hummingbird enable the animal to probe flowers that secrete nectar deep within floral tubes. Before the hummer leaves, anthers will dust its beak and head feathers with pollen. Many flowers that are pollinated by birds are red or pink, colors to which bird eyes are especially sensitive.

  44. Exploring Angiosperm Diversity EUDICOTS MONOCOTS Monocot Characteristics Eudicot Characteristics California poppy (Eschscholzia californica) Orchid (Lemboglossum fossii) Embryos One cotyledon Two cotyledons Leaf venation Pyrenean oak (Quercus pyrenaica) Veins usually netlike Veins usually parallel Pygmy date palm (Phoenix roebelenii) Stems Vascular tissue usually arranged in ring Lily (Lilium “Enchant- ment”) Vascular tissue scattered Roots Dog rose (Rosa canina), a wild rose Root system Usually fibrous (no main root) Taproot (main root) usually present Barley (Hordeum vulgare), a grass Pea (Lathyrus nervosus, Lord Anson’sblue pea), a legume Pollen Pollen grain with three openings Pollen grain with one opening Flowers Zucchini (Cucurbita Pepo), female (left) andmale flowers Anther Floral organs usually in multiples of three Floral organs usually in multiples of four or five Stigma Filament Ovary

  45. Human welfare depends greatly on seed plants No group is more important to human survival than seed plants Food for Thought

  46. Products from Seed Plants Humans depend on seed plants for Food Wood Many medicines

  47. Threats to Plant Diversity Destruction of Habitat Is causing extinction of many plant species and the animal species they support Disruption of Habitat Introduction of invasive and exotic species (competitors, predators, and pathogens)

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