Reproduction in Plants

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

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

Ovary Contains ovules, which produces megaspores  female gametophytes Complete flower – contains sepal, petal, carpel and stamen Perfect flower – contains stamen and carpel – bisexual, monoecious

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)

Life cycle fig Microsporocyte (microspore mother cell) undergoes meiosis  4 haploid microspores  pollen grains Megasporocyte (megaspore mother cell) undergoes meiosis  4 haploid megaspores  1 embryo sac

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