Sexual Reproduction in Plants

Sexual Reproduction in Plants

Flowering Plant Anatomy

• Flowering plants, or angiosperms, are the main group of plants that engage in sexual reproduction.

• The flower is the reproductive organ, and it contains both male and female parts, known as stamens and carpels respectively.

• Each stamen consists of an anther and a filament. The anther produces pollen, which contains the male sex cells or sperm.

• The carpal has an ovary, a style, and a stigma. The ovary contains the female sex cells or eggs, encased in ovules.

Pollination

• Pollination is the transfer of pollen from the anther to the stigma. It precedes fertilisation in the process of plant reproduction.

• This can occur through different vectors, including wind, insects, or other animals. Some plants even have adaptations to maximise their chances of successful pollination.

• Cross-pollination is favoured as it promotes genetic diversity. It involves the transfer of pollen from the anther of one plant to the stigma of another.

Fertilisation and Seed Development

• Fertilisation occurs when a pollen grain on the stigma grows a tube down the style, allowing sperm to travel down to the ovule and fertilise the egg.

• The fertilised egg becomes the zygote, which divides by mitosis to become the embryo.

• After fertilisation, the ovule wall becomes hard and forms a protective covering called the seed coat. The ovary itself develops into a fruit, which aids in seed dispersal.

Seed Germination and Plant Development

• Seed germination occurs when the seed absorbs water, swells, and breaks through the seed coat. The embryo starts to grow, using food stored in the seed until it can photosynthesise.

• This forms a seedling, which grows into a mature plant capable of sexual reproduction. The cycle thus continues.