Seed Plant Reproduction

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Seed Plant Reproduction
13.2
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Some Facts

• Flowering plants are the largest group of plants
• Flowers are adaptations for sexual reproduction
• An egg is fertilized by a sperm

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Flower Parts

• Petals ? usually the leafy colored parts
• Sepals ? small leaf-like parts outside the petals
• Stamen ? male reproductive organ made up of the
  filament and the anther where pollen forms
• Pistil ? female reproductive organ made up of the
  sticky stigma, the stalk-like style, and the
  ovary
• Ovary ? the swollen base of the pistil where
  ovules (eggs) are formed

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How's it happen ???

• Pollination the transfer of pollen grains
  (sperm) from the anthers to the stigmas ? occurs
  by wind, insects, birds, mammals
• Pollen grains (sperm) land on sticky stigma
• Pollen tube grows down into the ovary until it
  reaches the ovules (eggs)
• Sperm travels down pollen tube and fertilizes the
  egg
• Embryo part of seed develops
• Seeds develop into fruit and are eventually
  dispersed
• Germination ? the development of a seed into a
  new plant ? the time from planting until it rises
  from soil

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Fruit

• The ovary that surrounds the fertilized ovule
  becomes a fruit
• The fruit swells and ripens
• The fruit protects the developing seeds

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Fruits

• Fleshy fruits ? apples, oranges, peaches,
  cucumbers
• Dry fruits ? walnuts, acorns, peanuts
• Animals eat the fruits and disperse the seeds in
  their waste
• Some attach to animals fur coats and are
  dispersed (burrs)

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What's in a SEED ???

• A seed contains the embryo of a new plant
• Seed coat protection
• Endosperm supply of stored food to feed plant
  until it starts making its own food
• Cotyledons seed leaves
• Stem small and soft
• Root small (radicle)

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More about Seeds

• When fully developed the young plant inside a
  seed stops growing
• Dormant the inactive state of a seed when
  conditions are unfavorable for growth (drought,
  freezing temperatures)
• When in favorable conditions, seeds will sprout
  (germinate)
• To sprout, most seeds need water, air, warm
  temps

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Some Flower Plants Reproduce Asexually

• Plantlets tiny plants grow on edges of leaves,
  fall off and grow on their own
• Tuber underground stems that grow into new
  plants
• Runners above ground stems that grow along the
  ground and produce new plants

Bryophyllum
Potato
Strawberry
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