Sexual Reproduction in Flowering Plants
Production of Gametes
- In flowering plants, male and female gametes are produced in the anther and ovule (see diagram below for position of these structures), respectively
- Male gametes are contained within pollen grains, which are released from the anthers
- The anther contains pollen sacs
- Each pollen sac contains a diploid mothercell which undergoes meiosis to form four haploid pollen grains (the gametes)
- Mitosis occurs to produce more haploid male gametes
- Female gametes are made in the ovules
- A single diploid cell within the ovule undergoes meiosis to produce four haploid egg cells
- Only one of these cells survives which undergoes mitosis to produce female gametes
- Male gametes are contained within pollen grains, which are released from the anthers
Pollination and Fertilisation
- Pollination is the process of transferring pollen from the anther of one flower to the stigma of another
- Some flowering plants are hermaphroditic which means they contain both male and female parts
- Self pollination can occur in some of these species when pollen is transferred between different flowers on the same plant, or even from anther to stigma within the same flower
- Cross pollination is the transfer of pollen from one plant to another
- Flowers make use of a variety of methods, such as shape, colour and scent, to attract pollinators to aid with pollination
- All pollination methods are forms of sexual reproduction because the gametes are produced by meiosis so there is fusion of gametes to form a diploid nucleus
- Some flowering plants are hermaphroditic which means they contain both male and female parts
- After pollination has occurred, a pollen tube grows from the pollen grain down the style to the ovary of the plant
- The male nuclei travel down the pollen tube to the female ovule
- Two male nuclei travel down the pollen tube to the ovule; one will fuse with an ovule nucleus to form the zygote while the other will go on the form the plant embryo's food store
- Fertilisation occurs when the haploid male and female nuclei fuse and a diploid zygote is formed
- After fertilisation, the ovule becomes a seed and the ovary develops into the fruit
Fertilisation in flowering plants diagram
The process of fertilisation in a flowering plant to produce an embryo