Seed Plants cont.

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Seed Plants cont.

• B. Angiosperms (seed container seed formed in
  an ovary)
• Division Anthophyta (flowering plants)
• Class Monocotyledones (monocots) one seed leaf
  (stored food for embryo).
• Class Dicotyledones (dicots) two seed leaves.

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Monocots / Dicots

• Parallel leaf veins.
• One cotyledon.
• Floral parts in multiples of 3.
• Scattered vascular bundles.
• Net-like fibrous roots.
• No secondary (woody) growth).

• Branching leaf veins.
• Two cotyledons.
• Floral parts in multiples of 4 or 5.
• Vascular bundles arranged in ring.
• Tap roots.
• Secondary growth usually present.

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Flower Structure

• The flower is the sexual reproductive structure.
• Sepals usually green covering over bud calyx.
• Petals may attract pollinators corolla.
• Stamen male structure androecium.
• Carpel (pistil) female structure gynoecium.
• Flowers may be perfect with male and female
  parts, or imperfect with only one structure.

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Stamen Parts / Pistil Parts

• Stigma sticky tip, collects pollen.
• Style stalk that supports/elevates the stigma.
• Ovary contains the ovules (eggs).
• Ovary develops into fruit Ovule develops into
  seed.

• Anther pollen producing structure.
• Filament stalk with supports/elevates the
  anther.

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Sexual Reproduction in Flowering Plants

• Photoperiodicity sensitivity to light and
  darkness cycles.
• Length of dark critical in inducing blooming
  hormonal message from leaves.
• The mature plant is the sporophyte generation.
• In the ovule, the diploid megaspore mother cell
  undergoes meiosis, then mitosis to form 8 haploid
  nuclei called the female gametophyte.
• In anthers, diploid microspore mother cell
  divides by meiosis, then mitosis to form pollen
  grains each with two nuclei (male gametophyte)

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Pollination and Fertilization

• Pollination when pollen lands on the stigma.
• Pollen germinates as pollen tube grows down the
  style toward the ovary.
• Double fertilization -- one sperm nucleus
  fertilizes the egg (forms diploid zygote/new
  sporophyte) one sperm nucleus joins the 2
  endosperm nuclei (triploid, will form starch).
• Zygote/embryo and endosperm develop into a
  seed(s) ovary swells as fruit develops.

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Animation

• http//bcs.whfreeman.com/thelifewire/content/chp39
  /3902001.html

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Monocot seed

• Radicle embryonic root.
• Coleoptyle embryonic stem.
• Plumule first true leaves.
• Endosperm starchy food for embryo (popcornmmm,
  endosperm).

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Dicot seed

• Hypocotyl embryonic stem/root region below the
  cotyledon (seed leaf).
• Epicotyl embryonic stem region above the
  cotyledon.
• Plumule and a tough seed coat.

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3 Plant Tissues

• Embryonic protoderm ? dermal tissue (epidermis
  and root hairs)
• Procambrium ? vascular tissue (xylem, phloem, and
  cambium)
• Ground meristem ? ground tissue (parenchyma,
  collenchyma, sclerenchyma)

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Root Structure

• Epidermis
• Cortex/Pith parenchyma.
• Endodermis cells regulate movement of water
  in/out of vascular tissue.
• Pericycle produces secondary roots.
• Vascular cylinder xylem (tracheids and vessel
  elements) and phloem (sieve tubes and sieve
  cells).

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Monocot Root
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Dicot Root
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Stem Structure

• Vascular bundles xylem and phloem (and cambium
  in dicots).
• Sclerenchyma
• Cortex/Pith collenchyma and parenchyma.

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Monocot Stem
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Dicot Stem
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Regulation and Behavior

• Tropisms plants parts grow toward or away from
  an external stimulus.
• Phototropism positive in stems that grow
  toward the light.
• Gravitropism positive in roots that grow down
  with gravity negative in stems.
• Thigmotropism cells opposite from a touch will
  elongate tendrils coil around objects.

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Regulation and Behavior cont.

• 5 types of hormones
• 1. Auxins indoleacetic acid (IAA) and similar
  compounds.
• Promotes cell division and elongation produced
  by apical meristems.
• Inhibits axial meristem growth.
• Can produce fruits without fertilization.
• Most weed killers are synthetic auxins.

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Plant Hormones cont.

• 2. Gibberellins formed in young leaves and
  seeds.
• Cause cells to break down endosperm for growth.
• 3. Cytokinins formed in roots.
• Cause branching growth in stems and roots
  stimulates cell division.
• Synthetic gibberellins extend storage life of
  veggies.

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Plant Hormones cont.

• 4. Ethylene only hormone that is a gas.
• Initiates ripening of fruit contributes to plant
  aging.
• 5. Abscisic acid regulates leaf loss
  (abscission).
• Plant copes with dry seasons, pest attack, etc.