Sexual Reproduction in Plants

Flower Structure

The flower is the reproductive organ of most plants.
A typical flower consists of: sepals, petals, stamens and carpels.
Sepals protect the flower bud. Petals attract pollinators with bold colours and scents.
Stamens are the male reproductive structures. Each stamen consists of a filament and an anther, which produces pollen.
Carpels are the female reproductive structures. Each carpel consists of a stigma, style and ovary, which contains ovules.
The transfer of pollen from the anther of one flower to the stigma of another is known as cross-pollination.

Fertilisation and Seed Formation

Pollen grains germinate on the stigma, forming a pollen tube that grows down through the style to the ovary.
Fertilisation occurs when the male gamete from the pollen grain fuses with the female gamete in the ovule.
The fertilised ovule develops into a seed, the ovary wall develops into the fruit, protecting the seed.

Germination and Seedling Growth

For germination to occur, seeds require suitable conditions – such as moisture, warmth and anaerobic conditions.
The seed’s embryo begins to grow, using food reserves stored in the seed, until it’s able to photosynthesise on its own.
A root grows downwards and a shoot grows upwards, allowing for absorption of water and minerals from the soil, and light from the sun.
Eventually, this forms a new mature plant, capable of sexual reproduction and producing its own flowers and seeds.

Revision summary: Sexual reproduction in plants involves the structures of flowers and the process of cross-pollination. Fertilisation within the flower leads to the development of seeds, housed within fruit. Upon finding suitable conditions, seeds then germinate and grow into new plants, starting the reproductive cycle anew. Bell-ringer activity: Draw and label a diagram of a flower, including sepals, petals, stamen and carpel.