Pollination is the transfer of pollen from an anther to a stigma. Fertilisation is the fusion of a male nucleus with a female nucleus inside an ovule. One moves pollen between parts of a flower or between flowers. The other is what actually starts a new organism.
Questions often ask for both in the same answer, so the order and the wording matter. This lesson builds on identifying flower structures by role.
What happens between pollen landing and a seed forming?
The key is to follow the male nucleus on its journey.
- Pollination: pollen is carried by an insect or the wind and lands on a stigma.
- Pollen tube growth: the pollen grain grows a tube down through the style towards the ovary.
- Entering the ovule: the tube grows into an ovule through a tiny opening.
- Fertilisation: the male nucleus fuses with the female nucleus in the ovule. The fused cell is called a zygote.
- After fertilisation: the zygote divides to form an embryo inside the developing seed.
Pollination happens outside the ovary. Fertilisation happens deep inside it. That difference in location is a useful memory anchor.
Self-pollination and cross-pollination
Pollen can go to the same flower or to another one.
| Type | Where the pollen goes | Effect on offspring |
|---|---|---|
| Self-pollination | Stigma of the same plant | Less variation, since one parent supplies both nuclei |
| Cross-pollination | Stigma of a different plant of the same species | More variation, since two parents supply nuclei |
The inheritance model board shows how two sets of alleles combine in a simple fictional model, which helps to see why two parents give more variety.
Worked example
A flower is covered with a fine mesh bag before it opens, so no insect can reach it.
The student brushes pollen from another plant of the same species onto its stigma with a paintbrush, then replaces the bag. A fruit with seeds forms. Explain which processes occurred, in order.
Step 1, why the bag: the mesh stops insects delivering any other pollen, so all pollen came from the paintbrush.
Step 2, pollination: brushing the pollen on the stigma is pollination. It is cross-pollination, since the pollen came from a different plant.
Step 3, pollen tube: each grain that took grew a tube down the style to an ovule.
Step 4, fertilisation: the male nucleus fused with the female nucleus, and the fertilised ovules developed into seeds.
Answer: cross-pollination (by hand), then pollen tube growth, then fertilisation, then seed formation.
The mistake to watch for
A frequent slip is to say that pollination is when the male and female gametes join.
Mistaken answer: “Pollination is when the pollen fuses with the ovule to make a seed.”
The student merged two separate events into one.
The correction: pollination is only the landing of pollen on the stigma. The fusion of nuclei is fertilisation, and it happens later in the ovule. A safe sentence to write is “pollen is transferred to the stigma, then a pollen tube carries the male nucleus to the ovule, where fertilisation occurs”.
Check yourself
Answer on paper, then open each answer.
1. Decide whether each statement describes pollination or fertilisation: (a) a bee carries pollen between flowers; (b) two nuclei fuse inside an ovule.
Show answer
(a) Pollination. (b) Fertilisation.
2. Put in order: zygote forms; pollen lands on stigma; pollen tube grows down the style; male nucleus enters ovule.
Show answer
Pollen lands on stigma, then pollen tube grows down the style, then male nucleus enters ovule, then zygote forms.
3. Why is cross-pollination more likely to produce varied offspring than self-pollination?
Show answer
Two different plants supply the male and female nuclei, so the offspring receive a new combination of genes from two parents. With self-pollination, both nuclei come from one plant.
Where this leads next
Once the two events are separate in your mind, move on to explaining seed and fruit formation. The same stepwise habit helps every biology sequence question, and our teachers build it in online one-to-one Biology tuition.