Plantae

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Plantae

• Seed Plants

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Vascular Plants

• Formation of vascular tissue
• Xylem (water)
• Phloem (food)
• True leaves, roots, and stems
• Lignin
• Sporophyte generation dominate

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Alternation of Generation
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Alternation of Generation

• Sporophyte dependent on gametophyte
• mosses
• Large sporophyte and small independent
  gametophyte
• ferns
• Gametophyte dependent on sporophyte
• seed plants

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Why be Sporophyte Dominant?

• Reduced mutations
• UV light harmful to DNA
• Diploid (2n) form copes better with mutations
• two alleles

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Why Retain Gametophyte Generation?

• Ability to screen alleles
• doesnt require a large amount of energy
• Sporophyte embryos rely on some gametophyte tissue

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Seeds

• A seed is a sporophyte in a package
• spores are only single cells
• packaged with food
• All seed plants are heterosporous
• megasporangia
• microsporangia

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From Ovule to Seed
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Overview of Seed Plants

• Produce Seeds
• Can remain dormant for years
• Pollination replaces swimming sperm
• Gametophyte generation reduced
• Gymnosperms lack antheridium
• Angiosperms lack both archegonium and antheridium

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Phylogeny
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Gymnosperms(Naked Seed)

• Division Cycadophyta
• Division Ginkgophyta
• Division Gnetophyta
• Division Coniferophyta

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Ginkgophyta

• Ginkgo or Maidenhair Tree
• Characteristic leaves
• Only one species
• Only males are planted

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Cycadophyta

• Cycads
• Palm-like plants
• Sago Palms
• Leaves in cluster at top of trunks
• True Secondary growth

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Gnetophyta

• 3 Genera
• Ephedra
• Mormon Tea
• Ephedrine
• raises heart rate
• raises blood pressure

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Coniferophyta
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Coniferophyta

• Pine tree is the sporophyte generation
• Contains both male and female cones
• Pollen (staminate) cones (low in tree)
• produces pollen
• Ovulate cones (high in tree) with scales
• produces seeds

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Pine Life Cycle

• No Antheridium (microsporangia) produce pollen
  grain (4 cells)
• 2 prothallial cells
• 1 generative cell
• become a sterile cell and a spermatogenous cell
• produces 2 sperm
• 1 tube cell
• wings for dispersal

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Pine Life Cycle

• Ovule in a ovulate cone
• integument (seed coat) (2n)
• megasporangia (meiosis) or nucellus (nutrition)
  (2n)
• produces 4 megaspores (3 die)
• develops into female gametophyte
• archegonium with eggs (n)

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Angiosperms
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Angiosperm
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Flower

• Stamen
• Anther
• Filament
• Carpel
• Stigma
• Style
• Ovary with ovule

• Sepals
• Petals
• Receptacle

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Angiosperm Life Cycle
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Angiosperm Life Cycle

• No Antheridium (microsporangia)
• produce pollen grain
• 1 generative cell
• produces 2 sperm
• 1 tube cell

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Angiosperm Life Cycle

• Ovule in Ovary
• megasporangia
• produces 4 megaspores (3 die)
• develops into female gametophyte called the
  embryo sac

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Angiosperm Life Cycle

• Inside embryo sac
• 7 cells (eight nuclei) due to 3 mitotic divisions
• 3 antipodals
• 2 polar nuclei (one cell)
• 2 synergids
• 1 egg

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Angiosperm Life Cycle

• Double fertilization
• one sperm unites with egg
• one sperm unites with polar nuclei
• develops into endosperm (3n)
• Fruit and Seed development
• ovule seed
• ovary fruit

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Cross Pollination

• Most flowers do not self-pollinate
• stamen and carpal may develop at different times
• stamen and carpal may be arranged in flower to
  avoid contact

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Angiosperm Radiation

• Begins the Cenozoic era (65 mya)
• Most closely related to the Gnetophyta
• Coevolution
• the mutual influence of two species on each other
• plants and animals (insects, birds, bats)

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Pollination
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Dispersal
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The Global Impact

• Transformed atmosphere
• reduced carbon dioxide
• cooled the earth
• Nonrenewable resource