Reproduction of Seed Plants

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Reproduction of Seed Plants

• How is the plant kingdom different from other
  kingdoms?
• 4/17/07

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Reproduction with Cones and Flowers

• Alternation of Generations
• Sporophyte (diploid)begins with zygote
• Gametophyte (haploid)forms gametes
• Life cycle of Gymnosperms
• Reproduction takes place in cones
• Two types of cones
• Pollen and Seed Cone
• Near the base of scale are two ovules (female
  gamete)

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Reproduction with Cones and Flowers cont

• Pollination
• Gymnosperms life cycle takes two years to
  complete
• Male cones release pollen in spring
• Sticky secretion on female cone called
  pollination drop (catches pollen)
• Fertilization and Development
• Pollen lands near ovule begins to grow a pollen
  tube? two haploid sperm nuclei

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Reproduction with Cones and Flowers cont

• Structure of Flowers
• Four types of specialized leaves
• Sepals, petals, stamens, carpels
• Sepals and Petals
• Sepals? outermost circle of floral parts
• Petals? brightly colored found just inside sepals
• Sterile leavesno reproductive cells

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Reproduction with Cones and Flowers cont

• Stamens and Carpels
• StamenAnther and Filament (male Gametophyte)
• Filamentlong thin stalk that supports an anther
• Anther oval sac where meiosis
• Carpel or pistal? female gametophyte
• Ovarybroad base of the carpel (contains eggs)
• Style stalk that rises from the ovule
• Stigmatop of style

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Parts of a Flower
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Parts of a flower
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Reproduction with Cones and Flowers cont

• Life cycle of Angiosperms
• Reproduction takes place inside flower
• Pollination
• Most angiosperms are pollinated by animals

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Reproduction with Cones and Flowers cont

• Fertilization in Angiosperms
• Pollen land on stigma and develops pollen tube
  (forms two sperm cells)
• 1st sperm cell fertilizes egg 2nd fuses with
  endosperm forming triploid cell
• Triploid cell grows into the food-rich tissue
  (endosperm)

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Seed and Fruit Development

• Ovary walls thicken form fruit
• Fruit? applies to any seed enclosed within embryo
  wall
• Example of fruits
• Peas, corn, beans, rice, tomatoes, cucumbers,
  apples, grapes, strawberries

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Seed Dispersal

• Animals
• Eat fruit
• Disperse seed into area of less competition
• Wind and Water
• Lightweight
• Carried in the air or float on the surface of
  water

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Seed Dormancy

• Dormancy? period during which the embryo is alive
  but not growing
• Temperature, moisture can cause seed to end
  dormancy and germinate

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Seed Germination

• Seed Germination? Early growth stage of the plant
  embryo
• Seed absorbs water causing endosperm to swell,
  cracking open seed coat
• Monocots? cotyledon remain underground
• Dicots? Cotyledons emerge above ground

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Vegetative Reproduction

• Vegetative Reproduction? asexual reproduction
  allows a plant to produce offspring
• Allows plants to reproduce quickly

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Plant Propagation

• Use cutting, grafting, or budding to make
  identical copies of plant

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Cuttings

• Cut stem including buds (meristematic tissue)
• Bury stem in rooting mixture (containing plant
  hormones) stem grows roots

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Plant Propagation

• Grafting? stems used
• Budding? buds used
• New plants grown on plants with strong roots
• Piece of stem or lateral bud cut from parent and
  attached to another plant
• Cut piecescion
• Stockplant scion is attached

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Agriculture

• Modern farmingfoundation of human society
• Most people of the world depended on a few crops
• Wheat, rice, corn
• Selective breeding of crop plants and improved
  farming techniquesincrease efficiency and in
  crop yields