From fertilisation to seed

When a pollen grain lands on the right kind of stigma, it grows a thin pollen tube down through the style into the ovary.

The male gamete travels down the tube to an ovule and joins (fuses) with the egg cell. This joining is fertilisation: the start of a new life.

What each part becomes:

• The fertilised egg is the zygote; it grows into an embryo (a baby plant).
• The ovary swells into the fruit.
• Each ovule becomes a seed.

The juicy mango flesh you eat was the ovary; the stone (guthli) is the seed, with the baby plant and its packed food inside. A tomato has many seeds because many ovules were fertilised; a mango has one.

Seeds are scattered by wind, water and animals. Given water, air and the right temperature, a seed germinates: it sprouts into a new plant.

Plant breeding gives us better crops, ones that give more grain or resist disease:

• Selective breeding: choosing plants with good features to grow next.
• Artificial hybridisation: remove a flower's stamens, cover it with a bag, and put chosen pollen on it by hand.
• Genetic engineering: putting a useful gene into a plant.

An Indian pioneer. P. Maheshwari, the "Father of Indian Embryology", joined an egg and a male gamete in a test tube to make hybrid plants, and grew plant embryos on artificial food. His book An Introduction to the Embryology of Angiosperms (1950) is famous worldwide.