Transcript Flowering Plants

Plant Reproduction
Sexual Reproduction in flowering plants (3 min)
http://www.youtube.com/watch?v=1OFF2qYvLag&safe=active
Crash Course: Sexual Reproduction in Plants (10 min)
http://www.youtube.com/watch?v=ExaQ8shhkw8&safe=active
Sexual
Reproduction
• Flowering Plants (Angiosperms)
– Most successful and abundant modern day plants
– Reproductive structures found in flowers
– Seeds are enclosed with a “fruit” while developing
Flower Structure
• Stamens:
– Male portion of flower
– Filament stalk with anther tip
produces pollen grains
– Often more than one
– Thick walled pollen grains
contain 2 monoploid gametes
• Pistil: (carpel)
– Female portion of flower
– Usually located in the center
of the flower
– Stigma: at top of pistil, has
sticky surface to receive
pollen grains
– Style: fleshy tube supporting
stigma, connecting it to ovary
– Ovary: contains ovules
(monoploid gametes) that
develop into seeds
• The ovary itself will develop
into the “fruit”
• Rings of modified
leaves surround the
reproductive organs of
the flower
– Sepals:
• form a ring around the
base of the flower
• Enclose and protect the
flower bud before it
blooms
– Petals:
• often brightly colored to
attract pollinators
Pollination
• Transfer of pollen from anther
to stigma
– Self Pollination: flower
pollinates itself
– Cross Pollination: pollen is
taken from one plant to another
(get more genetic variation)
• Agents of Pollination:
– Wind, birds, bats, bees,
butterflies, wasps, flies, ants
– Plant often adapted to attract a
specific pollinator with showy
petals, aromas and nectar
The Biggest Flower in the World: (3 min)
http://www.youtube.com/watch?v=FHaWu2rcP94&safe=active
Fertilization
• Pollen grains land on stigma
and grow pollen tubes that
grows down through the style
to the ovary and enter the
ovule
• Double Fertilization
Occurs:
• One sperm fertilizes egg to
make diploid zygote
• One sperm fertilizes 2 polar
bodies forming triploid
endosperm (3n)
– This becomes the tissue that
stores food for the embryo
1 minute: http://videos.howstuffworks.com/discovery/30701-assignment-discovery-seed-dispersal-video.htm
Fruits and Seeds
• Each ovule develops
into a seed
• Ovary walls thicken
around the seed and
develop into the fruit
Seed Structure
• Seed Coat:
– tough protective coating
– Has a scar where it was
attached to the ovary
• Cotyledon:
– stores food for early
growth of embryo when
seed germinates
• Epicotyl:
– develops into stems and
leaves
• Hypocotyl:
– develops into roots
Seed Dispersal
• Dispersal:
– Plants have many
adaptations to help them
scatter their seeds
• Fruit dries and bursts open
(snapdragon)
• Carried by wind (dandelion)
• Carried by water (coconut)
• Burrs, hooks
• Fruits eaten by birds or other
animals and pooped out
•Seed Dispersal:http://www.youtube.com/watch?v=rhp5k5ptSx0&safe=active
Seed Germination
• Germination: “seed hatching”
– Seeds need water, oxygen, proper temperature
Germination: (1 min) http://science.howstuffworks.com/life/30704-assignment-discovery-germination-of-a-seed-video.htm