Reproduction in Plants

1
Reproduction in Plants
2
Flower

• Reproductive structure of angiosperm
• Sporophyte diploid
• Produces haploid spores
• Mitosis produces haploid gametophyte
• Two types of spores
• Microspores ? male gametophytes ? pollen grain
• Megaspores ? female gametophytes ? embryo sac
• Fertilization ? zygote becomes embryo within
  ovule ? seed
• Ovary becomes a fruit

3
Flower parts

• sepal green, protects bud
• Petal specific to pollinator, wind pollination
  may not have flowers
• Stamen male
• anther -pollen grains produced here from
  microspores
• filament
• Carpel female
• Stigma sticky knob
• Style - stalk
• Ovary base, contains ovules

4
Ovary

• Contains ovules, which produces megaspores ?
  female gametophytes
• Complete flower contains sepal, petal, carpel
  and stamen
• Perfect flower contains stamen and carpel
  bisexual, monoecious

5
Life cycle of flowering plants

• Sporophyte produces haploid spores ? grow and
  develop into haploid gametophytes ? mitosis ?
  gametes
• Heterosporous produce micro and megaspores
• Microspores produce sperm bearing pollen grains
  (male gametophytes)
• Megaspores produce egg bearing embryo sacs
  (female gametophytes)

6
Life cycle fig. 28.5

• Microsporocyte (microspore mother cell) undergoes
  meiosis ? 4 haploid microspores ? pollen grains
• Megasporocyte (megaspore mother cell) undergoes
  meiosis ? 4 haploid megaspores ?1 embryo sac

7
Pollination

• transfer of pollen from an anther to the stigma
  of a carpel
• Pollen tube is formed when pollen lands on stigma
• Double fertilization 1 sperm nucleus unites
  with the egg nucleus ? 2n zygote ? mitosis to
  form embryo
• Other sperm nucleus unties with polar nuclei of
  central cell and forms 3n endosperm cell
• Endosperm nourishes embryo and seedling during
  development