Quick answer: After fertilisation in a flower, the zygote divides many times to form the embryo; the ovule develops a tough coat and becomes the seed; the ovary grows and ripens into the fruit. The petals, sepals, stamens, style and stigma usually shrivel and fall off. Inside the seed, the plumule becomes the shoot, the radicle becomes the root, and the cotyledons store food.
What happens after fertilisation
Fertilisation is the fusion of the male germ cell (from the pollen grain) with the female germ cell (egg) in the ovule. It forms a zygote. After this:
- The zygote divides several times to form an embryo inside the ovule.
- The ovule develops a tough coat and is gradually converted into a seed.
- The ovary grows rapidly and ripens to form a fruit.
- The petals, sepals, stamens, style and stigma may shrivel and fall off.
Fate of each floral part
| Part of the flower | What it becomes | Why it matters |
|---|---|---|
| Zygote | Embryo | The future plant |
| Ovule | Seed | Holds and protects the embryo |
| Ovary | Fruit | Protects seeds and helps in their dispersal |
| Ovary wall | Fruit wall | Fleshy in mango, dry in a pea pod |
| Petals and stamens | Shrivel and fall off | Their job (attracting pollinators, making pollen) is over |
| Style and stigma | Shrivel and fall off | No longer needed |
| Sepals | Usually fall off | In some plants (tomato, brinjal, chilli) they stay on the fruit |
From ovule to seed
Step 1: The zygote divides repeatedly to form the embryo.
Step 2: Food is stored in the seed, often in the cotyledons (seed leaves).
Step 3: The outer layers of the ovule harden to form the seed coat, which protects the embryo.
Step 4: The seed dries out and can stay inactive (dormant) until conditions are right for growth.
Parts of a seed and germination
When a soaked gram or bean seed is opened, these parts can be seen:
| Part | Becomes or does |
|---|---|
| Plumule | Future shoot (stem and leaves) |
| Radicle | Future root |
| Cotyledons | Store food for the young plant |
| Seed coat | Protects the embryo |
Germination is the process in which the embryo in a seed grows into a seedling when it gets water, suitable temperature and oxygen. The radicle usually comes out first and grows down; the plumule grows up.
Memory aid: Radicle → Root; Plumule → shoot (the "plant" above ground).
Summary table
| Before | After |
|---|---|
| Zygote | Embryo |
| Ovule | Seed |
| Ovary | Fruit |
| Ovary wall | Fruit wall |
| Petals, stamens, style, stigma | Fall off |
Exam tips
- Learn the three key changes in order: zygote → embryo, ovule → seed, ovary → fruit.
- In diagrams of a germinating seed, label the plumule, radicle and cotyledon clearly.
- If asked "what happens to the petals?", say they shrivel and fall off because they are no longer needed.
- Use a simple example: a mango is a ripened ovary, and its stone holds the seed.
Common mistakes
- Mixing up the ovule and the ovary: the ovule becomes the seed, the ovary becomes the fruit.
- Swapping the plumule and radicle.
- Saying the zygote becomes the seed. The zygote becomes the embryo; the whole ovule becomes the seed.
- Thinking all floral parts fall off in every plant. In some plants the sepals stay on the fruit.
Frequently Asked Questions
What changes take place in a flower after fertilisation?
The zygote forms the embryo, the ovule becomes the seed, and the ovary ripens into the fruit. The petals, sepals, stamens, style and stigma usually shrivel and fall off.
What does the ovary develop into after fertilisation?
The ovary grows and ripens to form the fruit.
What does the ovule develop into?
The ovule develops a tough coat and becomes the seed, which contains the embryo.
What are the plumule and radicle?
The plumule is the part of the embryo that grows into the shoot, and the radicle is the part that grows into the root.
What conditions does a seed need to germinate?
A seed needs water, a suitable temperature and oxygen to germinate.