Quick answer: After fertilisation, the ovule develops into a seed, which contains the future plant, the embryo. A dicot seed such as gram or bean has a protective seed coat, two cotyledons that store food, and an embryo axis with a radicle (which grows into the root) and a plumule (which grows into the shoot). Under suitable conditions of water, air and warmth, the seed germinates into a seedling.
Where a seed comes from
After fertilisation in a flower, the ovule develops into a seed and the ovary grows into a fruit. NCERT describes it this way: the seed contains the future plant or embryo, which develops into a seedling under appropriate conditions. This process is called germination.
Parts of a dicot seed
| Part | What it is | Function |
|---|---|---|
| Seed coat | Tough outer covering | Protects the embryo |
| Micropyle | Tiny pore in the seed coat | Lets water in during germination |
| Cotyledons (two) | Seed leaves | Store food for the growing embryo |
| Radicle | Lower tip of the embryo axis | Grows into the root |
| Plumule | Upper tip of the embryo axis | Grows into the shoot |
"Dicot" means the seed has two cotyledons. Gram, pea and bean are common examples.
Opened gram seed
cotyledon | cotyledon
plumule
|
radicle
Radicle vs plumule
| Feature | Radicle | Plumule |
|---|---|---|
| Grows into | Root | Shoot |
| Direction of growth | Downwards (towards gravity) | Upwards (towards light) |
| Usually appears | First | After the radicle |
| Job of the part it forms | Anchors the plant, absorbs water | Carries leaves for photosynthesis |
Germination
Step 1: The seed absorbs water and swells. Much of the water enters through the micropyle, and the seed coat softens and splits.
Step 2: The embryo becomes active, and the stored food in the cotyledons is broken down to feed it.
Step 3: The radicle grows out first and moves down into the soil to form the root.
Step 4: The plumule grows upwards and forms the shoot with the first green leaves. Once the leaves can make food, the cotyledons shrivel.
Seeds need water, air (oxygen) and a suitable temperature to germinate.
Activity: observing a germinating gram seed
Step 1: Soak a few gram seeds in water overnight.
Step 2: Drain the extra water, cover the seeds with a wet cloth and leave them for a day. Keep them moist.
Step 3: Carefully open a seed and observe its parts: the two cotyledons, the radicle and the plumule.
Summary table
| Idea | Key fact |
|---|---|
| Seed | Develops from the ovule after fertilisation |
| Embryo | The future plant inside the seed |
| Cotyledons | Store food; dicots have two |
| Radicle | Becomes the root |
| Plumule | Becomes the shoot |
| Germination | Seed grows into a seedling with water, air and warmth |
Exam tips
- Draw and label the germinating seed with plumule, radicle and cotyledon; this diagram is in NCERT.
- Remember: Radicle → Root, Plumule → shoot (the part that points up).
- State the conditions for germination: water, air and a suitable temperature.
Common mistakes
- Swapping radicle and plumule.
- Saying cotyledons make food by photosynthesis. In the seed they store food.
- Forgetting that the seed comes from the ovule and the fruit from the ovary.
- Leaving out air (oxygen) as a condition for germination.
Frequently Asked Questions
What are the parts of a dicot seed?
The seed coat, two cotyledons and the embryo axis with the radicle and plumule.
What does the radicle become?
The radicle grows into the root of the new plant.
What does the plumule become?
The plumule grows into the shoot, which carries the stem and leaves.
What is the function of cotyledons?
They store food that nourishes the embryo until the seedling can make its own food.
What conditions does a seed need to germinate?
Water, air (oxygen) and a suitable temperature.