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💡 From pollen to a plant
Once pollen lands on the right stigma, a hidden race begins: a tube grows down to the ovule, gametes fuse, and a seed — a whole new plant in waiting — is born.
How does fertilisation happen in flowering plants?
- On a compatible stigma, a pollen grain grows a pollen tube down the style into the ovary (Fig. 11.14).
- The male gamete moves through this tube and fuses with the egg cell in the ovule.
- This fusion of gametes is fertilisation ; the fertilised egg is called a zygote , which develops into an embryo.
What happens to the ovule and ovary after fertilisation?
- The ovary enlarges and develops into a fruit .
- The ovules develop into seeds inside the fruit (Fig. 11.15).
- Seeds are dispersed by wind, water or animals; in favourable conditions a seed germinates into a new plant.
NCERT Question 2 — Arrange the following stages of
Arrange the following stages of sexual reproduction in plants in the correct order: (i) Pollen germination on stigma (ii) Fertilisation (iii) Pollination (iv) Formation of zygote
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🌎 Bridging Science and Society
- Sexual reproduction in plants has applied importance in plant breeding .
- Main methods: selective breeding, artificial hybridisation and genetically engineered crops.
- In selective breeding , farmers select plants of desirable characters for reproduction.
- Artificial hybridisation : remove the stamens from the chosen flower.
- Then bag the flower to prevent unwanted self-pollination.
- Manually transfer the desired pollen onto its stigma.
- Genetic engineering : insert genetic material of desired characters into the DNA.
- This gives new varieties — high-yielding and disease-resistant crops.
- Such methods have revolutionised crop production in agriculture.
Important Definitions
- Meiosis — cell division forming gametes that halves the chromosome number to haploid.
- Gamete — a haploid reproductive cell — sperm/egg in animals, carried by pollen/ovule in plants.
- Pollen grain — structure in the anther that carries the male gametes of a plant.
- Ovule — structure in the ovary that contains the egg cell; it becomes the seed.
- Sepal — the outermost green whorl of a flower that protects the bud.
- Petal — the coloured whorl of a flower that attracts pollinators.
- Stamen — the male part of a flower, made of a filament and a pollen-producing anther.
- Pistil — the female part of a flower, with stigma, style and ovary.
- Pollination — the transfer of pollen from the anther to the stigma of a flower.
- Self-pollination — pollen reaching the stigma of the same or another flower on the same plant.
- Cross-pollination — pollen transferred to the stigma of a flower on a different plant.
- Fertilisation — the fusion of the male and female gametes.
- Zygote — the fertilised egg that develops into an embryo.
⏸▶ Pause and Ponder
- 1. In a china-rose plant, a pollen tube grows through the style after pollen lands on the stigma — the next process is fertilisation (fusion of gametes in the ovule).
- 2. The light, tufted madar and dandelion seeds are adapted for wind dispersal .
- 3. Seeds forming only when pollen of one maize variety reaches the stigma of the other is cross-pollination .
