Fertilisation, Seed Formation and Dispersal

This lesson covers: 

  1. How fertilisation occurs in plants
  2. The development of seeds from ovules
  3. Different methods plants use to disperse seeds

Fertilisation in plants

In plants, the male gametes (sex cells) are contained within pollen grains, and they act like sperm in animals. The female gametes are found in the ovules. Each gamete contains a nucleus.

Diagram showing the process of fertilisation in plants, including pollen nucleus, pollen tube, style, ovary, ovule, and fertilisation.

When pollen lands on a stigma:

  1. A tube called a pollen tube grows out and extends down through the flower's style towards the ovary.
  2. A nucleus from the pollen grain moves down this tube to meet a nucleus in the female gamete (in an ovule inside the ovary).
  3. The male and female nuclei fuse together in a process called fertilisation, allowing genetic material to combine.

Seeds develop from ovules

Diagram showing the structure of a seed with labels for the seed coat, food store, and embryo.

After an egg cell is fertilised:

  1. The ovule matures into a seed containing an embryo plant and food supply.
  2. The food store provides nutrients to the embryo when the seed germinates.
  3. The ovary develops into a fruit around each seed.

Dispersal of seeds

Seed dispersal spreads out seeds so seedlings don't compete for resources.

Illustration showing seed dispersal methods including wind, animals, explosions, and gravity.

Common dispersal methods include:

  1. Wind - Blows seeds away e.g. dandelions, sycamores.
  2. Animals - Seeds excreted after fruits are eaten or seeds stick to fur e.g. blackberries.
  3. Explosions - Seed pods burst open flinging out seeds e.g. peas.
  4. Gravity - Fruits fall and roll away e.g. conkers.